{"title":"Baader Highspeed Narrowband Filters","description":"\u003cp\u003eBaader Highspeed narrowband filters are CMOS-optimized H-alpha, O-III and S-II filters designed for very fast optics at f\/2 and f\/3, such as RASA and Hyperstar systems. Their passband is matched to the steep light cone of these systems, so the emission line still reaches the sensor at full strength.\u003c\/p\u003e\u003cp\u003eChoose between Highspeed (6.5nm) and Ultra-Highspeed (3.5nm H-alpha, 4nm O-III and S-II) versions, sold individually or as complete H-alpha\/O-III\/S-II sets.\u003c\/p\u003e","products":[{"product_id":"baader-6-5nm-f-2-highspeed-filter-set-cmos-optimized-h-alpha-o-iii-s-ii","title":"Baader 6.5nm f\/2  Highspeed Filter Set - CMOS-Optimized H-alpha\/O-III\/S-II","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eSet of 3 Narrowband Filters: H-alpha, O-III, and S-II\u003c\/li\u003e\n\u003cli\u003e6.5nm Bandpass for high-contrast imaging\u003c\/li\u003e\n\u003cli\u003eOptimized for f\/2 to f\/3.5 High-Speed Optical Systems\u003c\/li\u003e\n\u003cli\u003ePre-shifted bandpass prevents signal loss from steep light cones\u003c\/li\u003e\n\u003cli\u003eCMOS-optimized with Reflex-Blocker™ coatings to eliminate halos\u003c\/li\u003e\n\u003cli\u003eSealed coating edges prevent moisture intrusion and aging\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eBaader 6.5nm f\/2 Highspeed Filter Set - CMOS-Optimized H-alpha\/O-III\/S-II\u003c\/h2\u003e\n\u003cp\u003eThe Baader 6.5nm f\/2 Highspeed Filter Set contains three essential narrowband filters (H-alpha, O-III, S-II) specifically engineered to maintain peak transmission when used with ultra-fast astrographs like Celestron RASA or Hyperstar systems. Standard narrowband filters suffer significant signal loss at focal ratios faster than f\/4, but this 6.5nm set is pre-shifted to perfectly align with the emission lines from an f\/2 light cone, ensuring maximum signal capture. This optimization allows modern CMOS sensors to record deep, high-contrast images of emission nebulae without the reflection halos or bandpass-shift issues that compromise data from fast optical systems.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eDesigned for f\/2 Systems: Pre-Shifted for Maximum Signal\u003c\/h3\u003e\n\u003cp\u003eIn a fast optical system, light rays approach the filter at a very steep angle, causing a phenomenon known as bandpass shift, where the filter's central wavelength shifts towards blue. A standard narrowband filter used at f\/2 can shift so much that it partially blocks the very emission line you're trying to capture. Baader's f\/2 Highspeed filters solve this by pre-shifting the central wavelength of the bandpass, ensuring that at f\/2, it is perfectly centered on the H-alpha, O-III, or S-II line for peak transmission.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCMOS-Optimized for 6.5nm Signals: Halation and Reflection Control\u003c\/h3\u003e\n\u003cp\u003eModern CMOS sensors, while incredibly sensitive, are also highly reflective. When paired with traditional filters, this can create strong halos and internal reflections around bright stars. The Baader Highspeed filters incorporate advanced Reflex-Blocker™ coatings that are hardened and optimized to suppress these reflections, delivering clean stellar profiles. Additionally, the coating edges are sealed (Life-Coat™), making them exceptionally durable and resistant to degradation from moisture, ensuring their high transmission for years of use.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e6.5nm Bandpass: High Contrast for Emission Nebulae\u003c\/h3\u003e\n\u003cp\u003eThe 6.5nm full width at half maximum (FWHM) strikes a critical balance between contrast and signal acquisition speed. This bandpass is narrow enough to dramatically darken the sky background, isolating faint nebular structures from moonlight and urban light pollution. At the same time, it is wide enough to deliver a strong signal, which is crucial for capturing data efficiently with fast f\/2 optical systems where exposure times are already significantly reduced.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eBaader f\/2 Highspeed vs. Standard Narrowband Filters\u003c\/h3\u003e\n\u003cp\u003eThe choice between this f\/2 Highspeed set and a standard narrowband filter set comes down to your telescope's focal ratio.\n\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard Filters (f\/4 and slower):\u003c\/strong\u003e These filters are designed for the shallower light cones of most refractors, SCTs, and Newtonians. Using them on an f\/2 system results in significant signal loss due to bandpass shift.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBaader f\/2 Highspeed Filters:\u003c\/strong\u003e These are purpose-built for systems from f\/2 to f\/3.5. Their pre-shifted design maximizes signal. Using them on a slower f\/8 telescope is a trade-off; the filter's center wavelength will be slightly offset from the emission line, resulting in a suboptimal, though still usable, signal.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat makes the Baader 6.5nm f\/2 Highspeed filters different from standard narrowband filters?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe key difference is their \u003cstrong\u003epre-shifted bandpass\u003c\/strong\u003e. Standard filters are designed for f\/4 or slower systems. When used at f\/2, the steep light cone shifts their transmission window, blocking part of the nebula's light. The Baader f\/2 Highspeed filters are manufactured to be perfectly on-band when used at f\/2, ensuring maximum signal throughput.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Baader f\/2 filters on my f\/8 Ritchey-Chrétien telescope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile you can, it is not optimal. These filters are pre-shifted for an f\/2 light cone. On an f\/8 system, the filter's bandpass will be slightly blue-shifted relative to the target emission line, resulting in a small reduction in signal. For f\/8 systems, a standard narrowband filter designed for slower focal ratios will deliver better results.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does \"CMOS-Optimized\" mean for the Baader Highspeed Filter Set?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt refers to the advanced \u003cstrong\u003eReflex-Blocker™ coatings\u003c\/strong\u003e applied to the filters. Modern CMOS sensors are very reflective, which can cause halos and artifacts around bright stars. These specialized coatings are designed to suppress these reflections, producing cleaner images with tighter star profiles, even on very bright targets.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the 6.5nm Baader filters perform on the Horsehead Nebula (Barnard 33) with my RASA 8?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis filter set is an ideal match for imaging the Horsehead Nebula with a RASA 8. The f\/2 focal ratio of the RASA is exactly what these filters are designed for. The \u003cstrong\u003e6.5nm H-alpha filter\u003c\/strong\u003e will provide excellent contrast to define the dark nebula against the glowing background of IC 434, capturing sharp detail with very short exposure times.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eAre these Baader f\/2 filters parfocal?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, Baader Planetarium engineers their CMOS-optimized filters to be parfocal. When you switch between the H-alpha, O-III, and S-II filters in this set, you should see minimal to no change in focus, saving valuable imaging time by eliminating the need to refocus with each filter change.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy would I choose a 6.5nm bandpass over a narrower 3nm filter for my f\/2 system?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eFor an f\/2 system, a \u003cstrong\u003e6.5nm bandpass\u003c\/strong\u003e is often a better compromise. While a 3nm filter provides higher contrast, it's more sensitive to bandpass shift and collects photons more slowly. The 6.5nm width provides excellent contrast while maintaining a very high signal acquisition rate, which is the primary advantage of using an f\/2 astrograph.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Set\u003c\/td\u003e\n\u003ctd\u003eH-alpha, O-III, S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCMOS Optimized\u003c\/td\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAvailable Sizes\u003c\/td\u003e\n\u003ctd\u003e1.25\" Mounted, 2\" Mounted, 31mm Unmounted, 36mm Unmounted, 50.4mm Unmounted, 50x50mm Unmounted, 65x65mm Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.02 (1.25\" Round Mounted)\u003cbr\u003e0.04 (2\" Round Mounted, 50.4mm Round Unmounted Filter)\u003cbr\u003e0.01 (31mm Round Unmounted Filter, 36mm Round Unmounted Filter)\u003cbr\u003e0.06 (50x50mm Square Filter)\u003cbr\u003e0.10 (65x65mm Square Filter)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround (1.25\" Round Mounted, 2\" Round Mounted, 31mm Round Unmounted Filter, 50.4mm Round Unmounted Filter, 36mm Round Unmounted Filter)\u003cbr\u003esquare (50x50mm Square Filter, 65x65mm Square Filter)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm) (1.25\" Round Mounted, 2\" Round Mounted)\u003cbr\u003eUnmounted (31mm Round Unmounted Filter, 50.4mm Round Unmounted Filter, 50x50mm Square Filter, 36mm Round Unmounted Filter, 65x65mm Square Filter)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Usage\u003c\/td\u003e\n\u003ctd\u003eCMOS, CCD, H-alpha, O-III, S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (1.25\" Round Mounted, 2\" Round Mounted, 31mm Round Unmounted Filter, 36mm Round Unmounted Filter)\u003cbr\u003e3 mm (50.4mm Round Unmounted Filter, 50x50mm Square Filter, 65x65mm Square Filter)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCWL (Central Wavelength)\u003c\/td\u003e\n\u003ctd\u003e656.3 nm \/ 500.7 nm \/ 671.7 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003c\/ul\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003cp\u003e\u003cem\u003eNote: This is a filter set containing three individual filters. Box contents may vary based on the specific size selected.\u003c\/em\u003e\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Filter_Problems_FAQ_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Filter Problems FAQ Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Narrowband_Filters_on_Astronomical_Telescopes_Whitepaper.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Narrowband Filters on Astronomical Telescopes Whitepaper\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"1.25\" Round Mounted","offer_id":44967356989725,"sku":"BAA-2961660","price":656.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Mounted","offer_id":44967357022493,"sku":"BAA-2961663","price":1079.0,"currency_code":"CAD","in_stock":true},{"title":"31mm Round Unmounted Filter","offer_id":44967357055261,"sku":"BAA-2961661","price":696.0,"currency_code":"CAD","in_stock":true},{"title":"50.4mm Round Unmounted Filter","offer_id":44967357088029,"sku":"BAA-2961664","price":1127.0,"currency_code":"CAD","in_stock":true},{"title":"50x50mm Square Filter","offer_id":44967357153565,"sku":"BAA-2961665","price":1298.0,"currency_code":"CAD","in_stock":true},{"title":"36mm Round Unmounted Filter","offer_id":44967357186333,"sku":"BAA-2961662","price":775.0,"currency_code":"CAD","in_stock":true},{"title":"65x65mm Square Filter","offer_id":44967357219101,"sku":"BAA-2961666","price":1611.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader-f-2-Highspeed-Filter-Set-H-alpha-O-III-S-II-1__52568.1597110925.1280.1280.jpg?v=1684341313"},{"product_id":"baader-3-5-4nm-f-2-ultra-highspeed-filter-set-cmos-optimized-h-alpha-o-iii-s-ii","title":"Baader 3.5\/4nm f\/2 Ultra-Highspeed Filter Set - CMOS-Optimized H-alpha\/O-III\/S-II","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e3.5nm (H-alpha, S-II) and 4nm (O-III) Bandpasses\u003c\/li\u003e\n\u003cli\u003eOptimized for f\/2 Ultra-Highspeed Optical Systems\u003c\/li\u003e\n\u003cli\u003eCMOS-Optimized with Reflex-Blocker™ Coatings\u003c\/li\u003e\n\u003cli\u003ePre-Shifted Center Wavelengths to Counteract Band-Shift\u003c\/li\u003e\n\u003cli\u003eLife-Coat™ Hard Coatings for Extreme Durability\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section-center\"\u003e\n      \u003ch2\u003eBaader 3.5\/4nm f\/2 Ultra-Highspeed Filter Set - CMOS-Optimized H-alpha\/O-III\/S-II\u003c\/h2\u003e\n      \u003cp\u003eThe Baader 3.5\/4nm f\/2 Ultra-Highspeed Filter Set is engineered specifically for modern, fast astrographs like Celestron RASA and HyperStar systems. This CMOS-optimized trio features ultra-narrow 3.5nm H-alpha and S-II filters and a 4nm O-III filter, all pre-shifted to place their transmission peaks precisely on the emission line when used in an f\/2 light cone. This design corrects for the inherent blue-shift that occurs with fast optics, ensuring you capture maximum signal without the transmission loss typical of standard narrowband filters on systems faster than f\/3.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eEngineered for f\/2 Systems: Pre-Shifted for Maximum Signal\u003c\/h3\u003e\n      \u003cp\u003eStandard narrowband filters suffer from band-shift when used in optical systems faster than f\/4; the steep light cone shifts the filter's transmission curve toward blue, causing it to miss the target emission line. Baader's f\/2 Ultra-Highspeed filters solve this by intentionally shifting the center wavelength during manufacturing. This ensures that at f\/2, the filter's passband is perfectly centered on the 656.3nm, 500.7nm, or 672.4nm lines, delivering nearly 100% of the available signal to your sensor.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n    \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eCMOS-Optimized Coatings: Halos and Reflections Suppressed\u003c\/h3\u003e\n      \u003cp\u003eModern CMOS sensors are notoriously reflective, often creating halos and internal reflections when paired with traditional filters. Every filter in this f\/2 set features Baader's Reflex-Blocker™ hard coatings and plane-optically polished surfaces. These treatments drastically reduce reflections, eliminating the halos around bright stars that can ruin an otherwise perfect image. Additionally, Baader's Life-Coat™ technology provides a hardened, scratch-resistant surface that withstands harsh cleaning and environmental conditions for years of use.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003e3.5nm \u0026amp; 4nm Bandpasses: Extreme Contrast for Emission Nebulae\u003c\/h3\u003e\n      \u003cp\u003eWith a full width at half maximum (FWHM) of just 3.5nm for H-alpha and S-II, and 4nm for O-III, these filters provide an extreme signal-to-noise ratio. This ultra-narrow bandpass rejects moonlight, city light pollution, and natural skyglow more effectively than wider 6.5nm or 7nm filters. The result is a darker background and significantly higher contrast, allowing faint structures within objects like the Pelican Nebula (IC 5070) or the Heart Nebula (IC 1805) to be recorded with greater clarity.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eBaader f\/2 Ultra-Highspeed vs. Standard f\/4+ Narrowband Filters\u003c\/h3\u003e\n      \u003cp\u003eWhile standard narrowband filters offer excellent results on slower systems, their performance degrades sharply at f\/2. This set is purpose-built for that specific application.\u003c\/p\u003e\n      \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eStandard 7nm Narrowband Filters:\u003c\/strong\u003e These are more forgiving on a wider range of focal ratios from f\/4 to f\/10. However, placed in an f\/2 system, their passband shifts so far that they may only transmit 50% or less of the target emission line's light.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eBaader f\/2 Ultra-Highspeed Filters:\u003c\/strong\u003e These are optimized for peak transmission from f\/1.8 to f\/3.5. On a slower f\/8 system, their pre-shifted bandpass would be off-target in the other direction, reducing their effectiveness. They are a specialist tool for a specialist optical system.\u003c\/li\u003e\n      \u003c\/ul\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n\u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Baader f\/2 Ultra-Highspeed filters on my f\/8 SCT?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eIt is not recommended. These Baader f\/2 filters are \"pre-shifted,\" meaning their center wavelength is intentionally offset to land perfectly on the emission line in a very fast f\/2 light cone. On an f\/8 system, this pre-shift would place the transmission band off-target, resulting in significant signal loss. For f\/4 or slower systems, Baader's standard 6.5nm or 7nm narrowband filters are the correct choice.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does \"CMOS-optimized\" mean for the Baader 3.5\/4nm filter set?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003e\u003cstrong\u003eCMOS-optimized\u003c\/strong\u003e refers to several design features that combat issues common with modern CMOS sensors. These include \u003cstrong\u003eReflex-Blocker™ coatings\u003c\/strong\u003e to prevent halos from reflections between the sensor and filter, plane-optically polished surfaces for sharpness, and sealed coating edges to prevent moisture intrusion. This ensures clean, artifact-free images even with bright stars in the field of view.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the 3.5nm bandpass on the Baader f\/2 filters affect imaging the Veil Nebula (NGC 6960) from my city backyard?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe ultra-narrow \u003cstrong\u003e3.5nm bandpass\u003c\/strong\u003e is extremely effective at isolating the specific light from the Veil Nebula while rejecting broad-spectrum light pollution from city skies. This drastically increases contrast, making the faint, filamentary structure of the nebula stand out against a dark background. Even with an f\/2 system's fast light-gathering ability, this level of filtering is critical for pulling out detail from light-polluted locations.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhy are the H-alpha and S-II filters 3.5nm while the Baader O-III filter is 4nm?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThis is a deliberate engineering choice. The O-III emission line is generally fainter in most nebulae compared to H-alpha. The slightly wider \u003cstrong\u003e4nm bandpass\u003c\/strong\u003e for O-III allows for slightly more signal to be gathered, improving the signal-to-noise ratio for this critical wavelength without compromising too much on contrast. The H-alpha and S-II lines can be filtered more aggressively at \u003cstrong\u003e3.5nm\u003c\/strong\u003e for maximum background rejection.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eAre these Baader 3.5\/4nm filters parfocal?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes, all Baader filters within a given size and series are designed to be parfocal. This means you should not need to make significant, if any, focus adjustments when switching between the H-alpha, O-III, and S-II filters in this set, saving valuable imaging time.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Baader f\/2 Ultra-Highspeed filter set work with my Celestron RASA 8 at f\/2?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eAbsolutely. This filter set is designed precisely for instruments like the RASA 8. The f\/2 optimization ensures you get maximum signal transmission by counteracting the band-shift inherent to the RASA's f\/2 optical design, making this set a perfect match for unlocking the full potential of your astrograph.\u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Set\u003c\/td\u003e\n\u003ctd\u003eH-alpha, O-III, S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eH-alpha Bandpass\u003c\/td\u003e\n\u003ctd\u003e3.5nm FWHM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eO-III Bandpass\u003c\/td\u003e\n\u003ctd\u003e4nm FWHM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eS-II Bandpass\u003c\/td\u003e\n\u003ctd\u003e3.5nm FWHM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePrimary Optimization\u003c\/td\u003e\n\u003ctd\u003ef\/1.8 to f\/3.5 optical systems\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ and Life-Coat™ Hard Coatings\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003ePlane-optically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAvailable Sizes\u003c\/td\u003e\n\u003ctd\u003e1.25\" Mounted, 2\" Mounted, 31mm Unmounted, 36mm Unmounted, 50.4mm Unmounted, 50x50mm Unmounted, 65x65mm Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.02 (1.25\" Round Mounted)\u003cbr\u003e0.04 (2\" Round Mounted, 50.4mm Round Unmounted Filter)\u003cbr\u003e0.01 (31mm Round Unmounted Filter, 36mm Round Unmounted Filter)\u003cbr\u003e0.06 (50x50mm Square Filter)\u003cbr\u003e0.10 (65x65mm Square Filter)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround (1.25\" Round Mounted, 2\" Round Mounted, 31mm Round Unmounted Filter, 36mm Round Unmounted Filter, 50.4mm Round Unmounted Filter)\u003cbr\u003esquare (50x50mm Square Filter, 65x65mm Square Filter)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm) (1.25\" Round Mounted, 2\" Round Mounted)\u003cbr\u003eUnmounted (31mm Round Unmounted Filter, 36mm Round Unmounted Filter, 50.4mm Round Unmounted Filter, 50x50mm Square Filter, 65x65mm Square Filter)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Usage\u003c\/td\u003e\n\u003ctd\u003eCMOS, CCD, H-alpha, O-III, S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/2 Ultra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (1.25\" Round Mounted, 2\" Round Mounted, 31mm Round Unmounted Filter, 36mm Round Unmounted Filter)\u003cbr\u003e3 mm (50.4mm Round Unmounted Filter, 50x50mm Square Filter, 65x65mm Square Filter)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCWL (Central Wavelength)\u003c\/td\u003e\n\u003ctd\u003e656.3 nm \/ 500.7 nm \/ 671.7 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cul class=\"DAV-grid\"\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eH-alpha 3.5nm f\/2 Ultra-Highspeed Filter\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eO-III 4nm f\/2 Ultra-Highspeed Filter\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eS-II 3.5nm f\/2 Ultra-Highspeed Filter\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eIndividual Filter Cases\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 3\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Filter_Problems_FAQ_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Filter Problems FAQ Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Narrowband_Filters_on_Astronomical_Telescopes_Whitepaper.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Narrowband Filters on Astronomical Telescopes Whitepaper\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"1.25\" Round Mounted","offer_id":44967910670621,"sku":"BAA-2961680","price":1151.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Mounted","offer_id":44967910703389,"sku":"BAA-2961683","price":1723.0,"currency_code":"CAD","in_stock":true},{"title":"31mm Round Unmounted Filter","offer_id":44967910736157,"sku":"BAA-2961681","price":1222.0,"currency_code":"CAD","in_stock":true},{"title":"36mm Round Unmounted Filter","offer_id":44967910768925,"sku":"BAA-2961682","price":1464.0,"currency_code":"CAD","in_stock":true},{"title":"50.4mm Round Unmounted Filter","offer_id":44967910801693,"sku":"BAA-2961684","price":1863.0,"currency_code":"CAD","in_stock":true},{"title":"50x50mm Square Filter","offer_id":44967910834461,"sku":"BAA-2961685","price":1986.0,"currency_code":"CAD","in_stock":true},{"title":"65x65mm Square Filter","offer_id":44967910867229,"sku":"BAA-2961686","price":2607.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader-f-2-Highspeed-Filter-Set-H-alpha-O-III-S-II-1__52568.1597110925.1280.1280__21214.1623461173.1280.1280.jpg?v=1684346897"},{"product_id":"baader-planetarium-h-alpha-f2-highspeed-filter-6-5nm-cmos-optimized","title":"Baader Planetarium H-alpha f\/2 Highspeed-Filter (6.5nm) – CMOS-optimized","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eEngineered for ultra-fast f\/2 optical systems\u003c\/li\u003e\n\u003cli\u003e6.5nm H-alpha bandpass for high-contrast imaging\u003c\/li\u003e\n\u003cli\u003eCMOS-optimized to suppress halos and internal reflections\u003c\/li\u003e\n\u003cli\u003eAvailable in 1.25\" \u0026amp; 2\" mounted, 31mm, 36mm, 47.4mm (FCCT) \u0026amp; 50.4mm round unmounted, and 50x50mm \u0026amp; 65x65mm square sizes\u003c\/li\u003e\n\u003cli\u003ePre-shifted design prevents signal loss from band-shifting\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eBaader H-alpha f\/2 Highspeed-Filter (6.5nm) – CMOS-optimized\u003c\/h2\u003e\n\u003cp\u003eThe Baader H-alpha f\/2 Highspeed-Filter is specifically engineered to maintain peak transmission on ultra-fast astrographs, using a pre-shifted 6.5nm bandpass to capture maximum signal at focal ratios down to f\/2. Offered in mounted 1.25\" and 2\" cells, as unmounted round filters (31mm, 36mm, 50.4mm and a 47.4mm version for the Baader FCCT) and as 50x50mm or 65x65mm squares, this CMOS-optimized filter delivers the high-contrast, halo-free hydrogen-alpha data required by modern imaging systems like the Celestron RASA or HyperStar.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eOptimized for f\/2 Systems: Peak Transmission Without Band-Shift\u003c\/h3\u003e\n\u003cp\u003eStandard narrowband filters suffer from band-shifting when used with fast optics; the steep light cone shifts the filter's transmission window away from the target wavelength, causing significant signal loss. Baader's Highspeed filters solve this by pre-shifting the bandpass, ensuring the H-alpha emission line remains centered even at f\/2, capturing the maximum available signal from emission nebulae.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e6.5nm CMOS-Optimized Design: High Contrast and Suppressed Halos\u003c\/h3\u003e\n\u003cp\u003eThe 6.5nm bandpass provides an excellent balance, delivering high-contrast views by rejecting light pollution and moonlight while remaining broad enough for strong signal on faint targets. Critically, every size is CMOS-optimized with advanced anti-reflection coatings and blackened edges, which drastically reduce the halos and internal reflections that can plague images from highly reflective modern sensors.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003ePlanoptically Polished Substrate: Maintaining Pinpoint Stars Across the Field\u003c\/h3\u003e\n\u003cp\u003eEach Baader filter is built on a planoptically polished substrate, ensuring it does not degrade the resolution of your main optics. This attention to optical flatness means stars remain sharp and pinpoint from edge to edge, preserving the fine details your telescope resolves. Choose the format that covers your sensor: 31mm filters suit sensors up to APS-C, while 50.4mm round and 50x50mm or 65x65mm square filters cover full-frame and larger detectors without vignetting. The hard, ion-beam-deposited dielectric coatings are scratch-resistant and do not degrade from proper cleaning.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eHigh-Speed vs. Standard Filters: Why Your f\/Ratio Demands a Specialized Filter\u003c\/h3\u003e\n\u003cp\u003eChoosing the right filter for your telescope's focal ratio is critical for narrowband imaging. While a standard filter works well at f\/7 or slower, its performance collapses at f\/4 or faster.\n\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard Narrowband Filter:\u003c\/strong\u003e At f\/2, a standard filter's center wavelength can shift several nanometers, effectively blocking the very H-alpha light you want to capture and acting more like a light pollution filter than a nebula filter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBaader f\/2 Highspeed Filter:\u003c\/strong\u003e This filter is purpose-built for the steep light cones of fast systems. Its pre-shifted design guarantees that maximum transmission occurs at f\/2, making it the correct choice for RASAs, HyperStars, and other fast astrographs.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat makes the Baader 6.5nm H-alpha filter a \"Highspeed\" filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA \"Highspeed\" filter is designed for very fast optical systems (typically f\/4 and faster). The filter's central wavelength is intentionally shifted during manufacturing to compensate for the blue-shift effect that occurs when light passes through an interference filter at a steep angle. This ensures that for an f\/2 system, the H-alpha line (656.3nm) is perfectly centered in the \u003cstrong\u003e6.5nm\u003c\/strong\u003e bandpass for maximum signal.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will this Baader f\/2 H-alpha filter perform on my Celestron RASA or HyperStar system?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis filter is designed precisely for those systems. A Celestron RASA or a Schmidt-Cassegrain with a HyperStar lens operates at f\/2, a focal ratio where standard narrowband filters fail due to band-shifting. The \u003cstrong\u003eBaader f\/2 Highspeed H-alpha filter\u003c\/strong\u003e is the correct tool to ensure you capture the strongest possible signal on emission nebulae like the North American Nebula (NGC 7000) or the Heart Nebula (IC 1805).\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Baader Highspeed 6.5nm H-alpha filter on my f\/8 refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt is not recommended. The pre-shifted bandpass is designed for fast f\/2 systems. At f\/8, the filter's transmission peak no longer sits on the H-alpha line, which reduces the signal you capture. For telescopes f\/4 and slower, Baader's standard narrowband filters are the recommended choice for peak performance.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does \"CMOS-optimized\" mean for the Baader 6.5nm H-alpha filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eModern CMOS sensors are highly reflective, which can cause halos around bright stars and other internal reflections when using older filters. \"CMOS-optimized\" means this Baader filter features advanced anti-reflection (AR) coatings, blackened filter edges, and other design elements to minimize these reflections, resulting in cleaner images with higher contrast and fewer artifacts.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eShould I choose this 6.5nm Baader Highspeed filter or a tighter 3.5nm version?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe choice depends on your sky conditions and targets. The \u003cstrong\u003e6.5nm\u003c\/strong\u003e bandpass is an excellent all-around choice, providing great contrast and collecting signal relatively quickly. A 3.5nm filter would offer even higher contrast and better rejection of light pollution, but requires significantly longer exposure times to achieve the same signal level. For most users, 6.5nm is the more practical starting point.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhich size of the Baader 6.5nm f\/2 Highspeed H-alpha filter fits my filter wheel or drawer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe mounted \u003cstrong\u003e1.25\"\u003c\/strong\u003e version uses standard M28.5 x 0.6 threads and threads into any 1.25\" filter wheel, filter drawer, or eyepiece that accepts threaded filters; the mounted \u003cstrong\u003e2\"\u003c\/strong\u003e version suits standard 2\" filter wheels and drawers. The unmounted \u003cstrong\u003e31mm\u003c\/strong\u003e size fits wheels such as ZWO's 7-position models, the \u003cstrong\u003e36mm\u003c\/strong\u003e size is common in wheels and drawers for astrographs like the RASA 8, and \u003cstrong\u003e50.4mm\u003c\/strong\u003e or \u003cstrong\u003e50x50mm\u003c\/strong\u003e filters suit full-frame wheels. The 47.4mm unmounted filter drops into the Baader FCCT for Celestron RASA systems, and the \u003cstrong\u003e65x65mm\u003c\/strong\u003e square requires a large-format wheel such as those from FLI or Moravian Instruments. Always confirm your wheel's requirements.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eSingle Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Usage\u003c\/td\u003e\n\u003ctd\u003eCMOS, CCD, H-alpha\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCWL (Central Wavelength)\u003c\/td\u003e\n\u003ctd\u003e656.3 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e1.25\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e1.25\" (1.25\")\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePhysical Format\u003c\/td\u003e\n\u003ctd\u003eMounted filter cell\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThread\u003c\/td\u003e\n\u003ctd\u003eM28.5 x 0.6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003ePlanoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e1.25 inch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/2 Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e6.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eH-alpha\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePhysical Format\u003c\/td\u003e\n\u003ctd\u003eMounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eAnti-reflection, blackened edges\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e2 inch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/2 Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e6.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eH-alpha\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Unmounted Filter (Ø 47.4mm, FCCT)\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize Class\u003c\/td\u003e\n\u003ctd\u003e2\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePhysical Format\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e47.4 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSystem Compatibility\u003c\/td\u003e\n\u003ctd\u003eBaader FCCT\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e31mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e31 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePhysical Format\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/2 Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e6.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eH-alpha\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e36 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePhysical Format\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/2 Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e6.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eH-alpha\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50.4mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50.4 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePhysical Format\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ anti-reflection\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/2 Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e6.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eH-alpha\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50x50mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50x50 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePhysical Format\u003c\/td\u003e\n\u003ctd\u003eUnmounted Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.02\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e50 x 50 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003esquare\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/2 Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e6.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eH-alpha\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e65x65 mm (Unmounted)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e6.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 High-Speed Systems\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized, Anti-Reflection\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.03\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003esquare\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003e2\" Round Unmounted Filter (Ø 47.4mm, FCCT)\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eFCCT H-alpha 2\" Unmounted Filter (47.4mm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003cp\u003eThis product is a single, unmounted filter. Mounting hardware and filter holders are not included.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Filter_Problems_FAQ_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Filter Problems FAQ Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Narrowband_Filters_on_Astronomical_Telescopes_Whitepaper.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Narrowband Filters on Astronomical Telescopes Whitepaper\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_We_Found_the_Way_Presentation_by_Christoph_Kaltseis.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium We Found the Way Presentation by Christoph Kaltseis\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_FCCT_Filter_Changer_Camera_Tilter_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium FCCT Filter Changer Camera Tilter Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium Warranty Policy\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"1.25\" Round Mounted","offer_id":52913180213533,"sku":"BAA-2961150","price":233.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Mounted","offer_id":52913180246301,"sku":"BAA-2961153","price":383.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Unmounted Filter (Ø 47.4mm, FCCT)","offer_id":52913180279069,"sku":"BAA-2961153U","price":335.0,"currency_code":"CAD","in_stock":true},{"title":"31mm Round Unmounted Filter","offer_id":52913180311837,"sku":"BAA-2961151","price":244.0,"currency_code":"CAD","in_stock":true},{"title":"36mm Round Unmounted Filter","offer_id":52913180344605,"sku":"BAA-2961152","price":274.0,"currency_code":"CAD","in_stock":true},{"title":"50.4mm Round Unmounted Filter","offer_id":52913180377373,"sku":"BAA-2961154","price":398.0,"currency_code":"CAD","in_stock":true},{"title":"50x50mm Square Filter","offer_id":52913180410141,"sku":"BAA-2961155","price":462.0,"currency_code":"CAD","in_stock":true},{"title":"65x65mm Square Filter","offer_id":52913180442909,"sku":"BAA-2961156","price":571.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-Baader-H-alpha-1-f-2-Highspeed-Filter-6-5nm-CMOS-optimized-1_72e65073-89cb-4d26-bdce-46aa4a026596.jpg?v=1789087393"},{"product_id":"baader-planetarium-h-alpha-f2-ultra-highspeed-filter-3-5nm-cmos-optimized","title":"Baader Planetarium H-alpha f\/2 Ultra-Highspeed-Filter (3.5nm) – CMOS-optimized","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eEngineered for f\/2 ultra-highspeed optical systems\u003c\/li\u003e\n\u003cli\u003e3.5nm bandpass for maximum H-alpha contrast\u003c\/li\u003e\n\u003cli\u003eCMOS-optimized with anti-reflection coatings\u003c\/li\u003e\n\u003cli\u003eAvailable in 1.25\" \u0026amp; 2\" mounted, 31mm, 36mm, 47.4mm (FCCT) \u0026amp; 50.4mm round unmounted, and 50x50mm \u0026amp; 65x65mm square sizes\u003c\/li\u003e\n\u003cli\u003ePre-shifted design prevents signal loss from band-shift\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eBaader H-alpha f\/2 Ultra-Highspeed-Filter (3.5nm) – CMOS-optimized\u003c\/h2\u003e\n\u003cp\u003eThe Baader H-alpha f\/2 Ultra-Highspeed Filter is specifically designed to isolate the 656.3nm H-alpha line in optical systems as fast as f\/2 without signal loss. Its narrow 3.5nm bandpass is pre-shifted to counteract the blue-shift effect inherent in fast optics, ensuring that imagers using RASA, HyperStar, or other fast astrographs capture the maximum available signal from emission nebulae. It is offered in mounted 1.25\" and 2\" cells, as unmounted 31mm, 36mm, 47.4mm and 50.4mm round filters, and as 50x50mm and 65x65mm squares for large-format sensors.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eEngineered for f\/2 Systems: Preventing Band-Shift in Fast Optics\u003c\/h3\u003e\n\u003cp\u003eStandard narrowband filters suffer from band-shift when used in fast f-ratio telescopes. As the light cone becomes steeper, the filter's central wavelength shifts, causing it to misalign with the target emission line and leading to significant signal loss. The Baader f\/2 Ultra-Highspeed filter solves this by being physically pre-shifted, ensuring the 3.5nm bandpass remains perfectly centered on the H-alpha line even at f\/2.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eA 3.5nm Bandpass for Extreme Contrast on Emission Nebulae\u003c\/h3\u003e\n\u003cp\u003eWith a full width at half maximum (FWHM) of just 3.5nm, this filter provides a dramatic increase in contrast compared to wider filters. It aggressively rejects moonlight, light pollution, and unwanted starlight, making faint hydrogen structures in targets like the North American Nebula (NGC 7000) or the Heart Nebula (IC 1805) stand out against a dark sky background. This narrow window is ideal for teasing out the finest details in complex H-II regions.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCMOS-Optimized Coatings to Suppress Halos Around Bright Stars\u003c\/h3\u003e\n\u003cp\u003eModern CMOS sensors are notoriously reflective, often causing halos and internal reflections when paired with traditional filters. This Baader filter features advanced anti-reflection coatings that are optimized for these sensors. By minimizing reflections between the filter and the sensor package, it delivers clean, halo-free stars, even in dense star fields or when imaging targets next to bright stars like Alnitak in the Horsehead Nebula (Barnard 33) region.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003ef\/2 Highspeed vs. Standard Narrowband Filters: Why F-Ratio Matters\u003c\/h3\u003e\n\u003cp\u003eWhile a standard 7nm or 6nm narrowband filter performs well at f\/4 and slower, its transmission can plummet in a faster system. The primary advantage of a standard filter is often a lower cost, making it a perfectly valid choice for systems that do not require band-shift correction. However, for RASA, HyperStar and other astrographs working near f\/2, the Baader f\/2 Ultra-Highspeed filter isn't just an improvement—it's a necessity for preventing data loss and achieving the highest possible signal-to-noise ratio.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDo I need the Baader f\/2 Ultra-Highspeed filter for my f\/5 telescope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, for systems at f\/4 or slower, a standard Baader narrowband filter will perform excellently without significant band-shifting issues. The f\/2 Ultra-Highspeed series is specifically engineered for the extremely steep light cones of systems like Celestron RASA, Starizona HyperStar, and other astrographs operating below f\/4.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat happens if I use a standard H-alpha filter in my RASA at f\/2?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIf you use a standard, non-shifted narrowband filter in an f\/2 system, you will experience significant signal loss. The filter's passband will shift away from the H-alpha emission line, effectively blocking a large portion of the light from the nebula you are trying to capture. This results in faint, low-contrast images, regardless of exposure time.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the 3.5nm bandpass on this Baader filter affect my images of the Orion Nebula (M42)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe 3.5nm bandpass will produce extremely high contrast on the hydrogen gas structures within the Orion Nebula (M42). It will darken the sky background significantly, making the faint outer loops of the nebula more visible while retaining sharp detail in the bright Trapezium region. The CMOS-optimization will also help control the intense brightness of the core stars, reducing halos.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhich size of the Baader 3.5nm f\/2 Ultra-Highspeed H-alpha filter do I need?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eMatch the size to your filter wheel or drawer and your sensor. The \u003cstrong\u003e1.25\"\u003c\/strong\u003e and \u003cstrong\u003e2\"\u003c\/strong\u003e versions come in standard mounted cells, the 2\" cell carrying M48x0.75 threads. The unmounted \u003cstrong\u003e31mm\u003c\/strong\u003e size suits many ZWO and QHY wheels for APS-C or smaller sensors, while \u003cstrong\u003e36mm\u003c\/strong\u003e fits larger wheels and drawers for sensors the 1.25\" format cannot cover without vignetting. The \u003cstrong\u003e47.4mm\u003c\/strong\u003e unmounted filter is made for FCCT filter holders on Celestron RASA astrographs, and the \u003cstrong\u003e50.4mm\u003c\/strong\u003e round and \u003cstrong\u003e50x50mm\u003c\/strong\u003e or \u003cstrong\u003e65x65mm\u003c\/strong\u003e square formats cover full-frame and larger sensors. Unmounted filters have no threads and need a compatible holder, drawer or wheel. All sizes are intended for astrophotography only, not visual use.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does 'CMOS-optimized' mean for the Baader 3.5nm H-alpha filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003e\u003cb\u003e'CMOS-optimized'\u003c\/b\u003e means the filter features advanced anti-reflection coatings designed to prevent halos that can occur from light reflecting between the filter and a modern, highly-reflective CMOS sensor. This results in cleaner stellar profiles and higher-quality raw data.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the 3.5nm bandpass require longer exposure times than a 7nm filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, all else being equal, a narrower bandpass gathers less light per unit of time. However, this filter is designed for ultra-fast f\/2 systems, which gather light at an exceptional rate. The combination of the fast optics and the high-contrast filter allows for shorter total integration times to achieve a high signal-to-noise ratio, even with longer individual sub-exposures.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eSingle Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Usage\u003c\/td\u003e\n\u003ctd\u003eCMOS, CCD, H-alpha\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCWL (Central Wavelength)\u003c\/td\u003e\n\u003ctd\u003e656.3 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e1.25\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized F-Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApplication\u003c\/td\u003e\n\u003ctd\u003eAstrophotography\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Unmounted Filter (Ø 47.4mm, FCCT)\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eHydrogen-alpha (H-alpha)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\" Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e47.4 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized For\u003c\/td\u003e\n\u003ctd\u003ef\/2 Ultra-Highspeed Systems\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eProduct Line\u003c\/td\u003e\n\u003ctd\u003eFCCT (Fast Corrected Coma-free Telescope)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e31mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Narrowband H-alpha\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e31 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e3.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Ultra-Highspeed Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e36 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e3.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50.4mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Highspeed Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWavelength\u003c\/td\u003e\n\u003ctd\u003eH-alpha (Pre-shifted)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50.4mm Round, Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized, Reflex-Blocker, Life-Coat Edge Sealed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50x50mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Highspeed Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass\u003c\/td\u003e\n\u003ctd\u003eH-alpha\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFWHM\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50x50 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized F-Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/1.8 to f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Anti-Reflection\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.02\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003esquare\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e65mm x 65mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTechnology\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized, Ultra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.03\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e65 x 65 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003esquare\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003e2\" Round Unmounted Filter (Ø 47.4mm, FCCT)\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eFCCT H-alpha 2\" Unmounted Filter (47.4mm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader H-alpha 3.5nm f\/2 Filter (36mm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eProtective Filter Case\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e50.4mm Round Unmounted Filter\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eBaader H-alpha 3.5nm f\/2 Ultra-Highspeed Filter (50.4mm)\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eFilter Storage Box\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003ch3\u003e50x50mm Square Filter\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader H-alpha 50x50mm f\/2 Ultra-Highspeed Filter (3.5nm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eFilter Storage Box\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader H-alpha 65x65mm f\/2 Ultra-Highspeed-Filter (3.5nm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Filter_Problems_FAQ_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Filter Problems FAQ Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Cleaning_and_Maintenance_of_Optics_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Cleaning and Maintenance of Optics Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Narrowband_Filters_on_Astronomical_Telescopes_Whitepaper.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Narrowband Filters on Astronomical Telescopes Whitepaper\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_We_Found_the_Way_Presentation_by_Christoph_Kaltseis.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium We Found the Way Presentation by Christoph Kaltseis\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_FCCT_Filter_Changer_Camera_Tilter_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium FCCT Filter Changer Camera Tilter Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"1.25\" Round Mounted","offer_id":52913182572829,"sku":"BAA-2961375","price":431.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Mounted","offer_id":52913182605597,"sku":"BAA-2961378","price":677.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Unmounted Filter (Ø 47.4mm, FCCT)","offer_id":52913182638365,"sku":"BAA-2961378U","price":609.0,"currency_code":"CAD","in_stock":true},{"title":"31mm Round Unmounted Filter","offer_id":52913182671133,"sku":"BAA-2961376","price":446.0,"currency_code":"CAD","in_stock":true},{"title":"36mm Round Unmounted Filter","offer_id":52913182703901,"sku":"BAA-2961377","price":541.0,"currency_code":"CAD","in_stock":true},{"title":"50.4mm Round Unmounted Filter","offer_id":52913182736669,"sku":"BAA-2961379","price":743.0,"currency_code":"CAD","in_stock":true},{"title":"50x50mm Square Filter","offer_id":52913182769437,"sku":"BAA-2961380","price":842.0,"currency_code":"CAD","in_stock":true},{"title":"65x65mm Square Filter","offer_id":52913182802205,"sku":"BAA-2961381","price":1079.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-Baader-H-alpha-1-f-2-Ultra-Highspeed-Filter-3-5nm-CMOS-optimized-1_b633f362-cd0d-41e7-9b54-5eff6af1b766.jpg?v=1789087465"},{"product_id":"baader-planetarium-h-alpha-f3-ultra-highspeed-filter-3-5nm-cmos-optimized","title":"Baader Planetarium H-alpha f\/3 Ultra-Highspeed-Filter (3.5nm) – CMOS-optimized","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e3.5nm H-alpha Bandpass\u003c\/li\u003e\n\u003cli\u003eOptimized for f\/3 Ultra-High-Speed Systems\u003c\/li\u003e\n\u003cli\u003eAvailable in 1.25\" \u0026amp; 2\" mounted, 31mm, 36mm \u0026amp; 50.4mm round unmounted, and 50x50mm \u0026amp; 65x65mm square sizes\u003c\/li\u003e\n\u003cli\u003eCMOS-Optimized Anti-Reflection and Anti-Halo Coatings\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eBaader H-alpha f\/3 Ultra-Highspeed-Filter (3.5nm) – CMOS-optimized\u003c\/h2\u003e\n\u003cp\u003eThe Baader H-alpha f\/3 Ultra-Highspeed-Filter is specifically engineered for modern astrographs, delivering the full contrast of its tight 3.5nm bandpass on optical systems down to f\/3. Offered in mounted 1.25\" (M28.5x0.6) and 2\" cells, as unmounted 31mm, 36mm and 50.4mm round filters, and as 50x50mm or 65x65mm squares, it uses a pre-shifted design to ensure the critical H-alpha emission line is not lost to bandpass shift, a common failure point for conventional narrowband filters on fast scopes.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eOptimized for f\/3 Optics: Maximizing Signal on Fast Telescopes\u003c\/h3\u003e\n\u003cp\u003eStandard narrowband filters are designed for slower telescopes. When used on a fast f\/3 system, the steep light cone causes a \"blue shift\" in the filter's bandpass, moving it away from the H-alpha wavelength and causing significant signal loss. Baader's f\/3 Ultra-Highspeed filter is pre-shifted to be perfectly on-band at these fast focal ratios, ensuring maximum signal capture from emission nebulae.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e3.5nm Bandpass: Extreme Contrast on H-alpha Targets\u003c\/h3\u003e\n\u003cp\u003eWith a narrow 3.5nm bandpass, this filter dramatically increases contrast by rejecting unwanted light from moonlight, artificial light pollution, and natural skyglow. This isolates the H-alpha signal, darkening the sky background and making faint nebulosity stand out. The narrow window also tightens stars by blocking more of their continuum spectrum, preventing bloat on long exposures.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCMOS-Optimized Coatings for High-Reflectivity Sensors\u003c\/h3\u003e\n\u003cp\u003eModern CMOS sensors are highly reflective, which can create halos and internal reflections when paired with traditional filters. This Baader filter features advanced coatings specifically designed to be \"CMOS-optimized.\" These coatings suppress reflections between the filter and the sensor, eliminating artifacts around bright stars and preserving the clean, high-contrast background your fast optics can deliver. The unmounted 31mm size suits filter wheels for APS-C or smaller sensors, 36mm fits standard wheels for larger chips, and the 50.4mm round and 50x50mm or 65x65mm square formats illuminate full-frame and larger sensors without vignetting.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eHigh-Speed f\/3 vs. Conventional f\/10 Filters: The Critical Difference\u003c\/h3\u003e\n\u003cp\u003eChoosing the right filter for your telescope's focal ratio is essential for narrowband imaging. While a conventional filter is a great choice for a slower instrument, it becomes a bottleneck on a fast system.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eConventional f\/10 Filter:\u003c\/strong\u003e On slower telescopes, these filters perform exactly as specified. However, at f\/3, their bandpass shifts so far that a significant portion of the H-alpha light you're trying to capture is blocked.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBaader f\/3 High-Speed Filter:\u003c\/strong\u003e This filter is purpose-built for the steep light cones of f\/3 systems. Its pre-shifted bandpass ensures that the peak H-alpha transmission aligns perfectly with your fast optics, resulting in brighter, higher-signal images in less time.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat makes the Baader f\/3 H-alpha filter different from a standard 3.5nm filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA standard \u003cstrong\u003e3.5nm filter\u003c\/strong\u003e is designed for slower telescopes. The \u003cstrong\u003eBaader f\/3 Ultra-Highspeed filter\u003c\/strong\u003e is \"pre-shifted,\" meaning its bandpass is centered correctly for the steep light cone of an f\/3 optical system. This prevents the signal loss that occurs when using a conventional filter on a fast telescope like a RASA or HyperStar.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the Baader 3.5nm f\/3 H-alpha filter perform on my Celestron RASA or HyperStar system?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA Celestron RASA or a telescope with a Starizona HyperStar operates at a very fast focal ratio (around f\/2 to f\/3). The \u003cstrong\u003eBaader f\/3 H-alpha filter\u003c\/strong\u003e will perform far better than a standard filter on such systems, allowing you to capture deep, high-contrast images of emission nebulae like the North America Nebula (NGC 7000). It is optimized for systems around f\/3; on systems faster than f\/3, such as an f\/2 RASA, some band-shift may remain, and Baader's f\/2 Highspeed filter series is matched more precisely to that focal ratio.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Baader f\/3 Ultra-Highspeed H-alpha filter on my f\/8 refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt is not recommended. Because the filter is pre-shifted for f\/3 systems, using it at f\/8 will place the bandpass off the H-alpha line in the other direction, causing signal loss. For an f\/8 telescope, a conventional narrowband filter designed for slower focal ratios is the better choice.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy is the Baader f\/3 H-alpha filter \"CMOS-optimized\"?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003e\"CMOS-optimized\" refers to the advanced anti-reflection coatings. Modern CMOS sensors have highly reflective surfaces that can cause halos and internal reflections with standard filters. The coatings on the \u003cstrong\u003eBaader f\/3 H-alpha filter\u003c\/strong\u003e are designed to suppress these reflections, resulting in cleaner images with fewer artifacts, especially around bright stars.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Baader 3.5nm f\/3 H-alpha filter help me image the Horsehead Nebula (Barnard 33) from my light-polluted backyard?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, absolutely. The very narrow \u003cstrong\u003e3.5nm bandpass\u003c\/strong\u003e is extremely effective at blocking out broadband light pollution. By isolating just the H-alpha light from the nebula behind the Horsehead, this filter will dramatically increase the contrast of your image, making it possible to capture faint details even from urban or suburban locations.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDo I need longer exposures with this 3.5nm Baader f\/3 H-alpha filter compared to a 7nm filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAll else being equal, a \u003cstrong\u003e3.5nm filter\u003c\/strong\u003e passes half the light of a 7nm filter and would typically require longer exposures. However, this filter is designed for ultra-fast f\/3 systems which gather light much more quickly than slower scopes. The extreme light-gathering power of the telescope compensates for the narrower bandpass, allowing you to capture deep data efficiently.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eSingle Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Usage\u003c\/td\u003e\n\u003ctd\u003eCMOS, CCD, H-alpha\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCWL (Central Wavelength)\u003c\/td\u003e\n\u003ctd\u003e656.3 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 to f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e1.25\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e1.25 inch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\" (Mounted)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e31mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e31mm, Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRecommended Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e36mm, Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSeries\u003c\/td\u003e\n\u003ctd\u003eUltra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/3 Ultra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e3.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eH-alpha\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50.4mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50.4mm (unmounted)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3 to f\/5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ Hard Coated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003ePlaneoptically Polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50x50mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50x50 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e3.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSeries\u003c\/td\u003e\n\u003ctd\u003eUltra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized, Reflex-Blocker™, Life-Cal™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.02\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eH-alpha, CMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e65mm x 65mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimal Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.03\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e65 x 65 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader H-alpha f\/3 Ultra-Highspeed-Filter (3.5nm), selected size\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eFilter Storage Case (2\" mounted version)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Filter_Problems_FAQ_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Filter Problems FAQ Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Narrowband_Filters_on_Astronomical_Telescopes_Whitepaper.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Narrowband Filters on Astronomical Telescopes Whitepaper\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium Warranty Policy\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"1.25\" Round Mounted","offer_id":52913185423645,"sku":"BAA-2961350","price":417.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Mounted","offer_id":52913185456413,"sku":"BAA-2961353","price":597.0,"currency_code":"CAD","in_stock":true},{"title":"31mm Round Unmounted Filter","offer_id":52913185489181,"sku":"BAA-2961351","price":439.0,"currency_code":"CAD","in_stock":true},{"title":"36mm Round Unmounted Filter","offer_id":52913185521949,"sku":"BAA-2961352","price":526.0,"currency_code":"CAD","in_stock":true},{"title":"50.4mm Round Unmounted Filter","offer_id":52913185554717,"sku":"BAA-2961354","price":651.0,"currency_code":"CAD","in_stock":true},{"title":"50x50mm Square Filter","offer_id":52913185587485,"sku":"BAA-2961355","price":746.0,"currency_code":"CAD","in_stock":true},{"title":"65x65mm Square Filter","offer_id":52913185620253,"sku":"BAA-2961356","price":934.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-Baader-H-alpha-1-f-3-Ultra-Highspeed-Filter-3-5nm-CMOS-optimized-1_e2a9fb13-a3ab-4042-ae05-4d9394c41fcb.jpg?v=1789087537"},{"product_id":"baader-planetarium-o-iii-f2-highspeed-filter-6-5nm-cmos-optimized","title":"Baader Planetarium O-III f\/2 Highspeed-Filter (6.5nm) – CMOS-optimized","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e6.5nm FWHM Bandpass for O-III\u003c\/li\u003e\n\u003cli\u003eOptimized for f\/2 to f\/3.5 High-Speed Optical Systems\u003c\/li\u003e\n\u003cli\u003eAvailable in 1.25\" \u0026amp; 2\" Mounted, 31mm, 36mm, 47.4mm (FCCT) \u0026amp; 50.4mm Round Unmounted, and 50x50mm \u0026amp; 65x65mm Square Sizes\u003c\/li\u003e\n\u003cli\u003eCMOS-Optimized with Reflex-Blocker™ Coatings\u003c\/li\u003e\n\u003cli\u003eSealed Coating Edges with Life-Coat™ Durability\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eBaader O-III f\/2 Highspeed-Filter (6.5nm) – CMOS-optimized\u003c\/h2\u003e\n\u003cp\u003eThe Baader O-III f\/2 Highspeed-Filter isolates the critical Oxygen-III emission line with a tight 6.5nm bandpass, engineered to maintain full transmission on optical systems as fast as f\/2. Offered as mounted 1.25\" and 2\" filters, as unmounted round filters (31mm, 36mm, 50.4mm and a 47.4mm version for the Baader FCCT) and as 50x50mm and 65x65mm squares, it is specifically designed to counteract the bandpass shift inherent in fast optics, ensuring that your CMOS sensor captures maximum signal from planetary nebulae and supernova remnants without halos or internal reflections.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eEngineered for f\/2 Systems: Maintaining Signal at Fast Focal Ratios\u003c\/h3\u003e\n\u003cp\u003eStandard narrowband filters suffer from a phenomenon called bandpass shift when used with fast focal ratios; the incoming light cone is so steep that the filter's central wavelength moves, causing significant signal loss. The Baader f\/2 Highspeed filter solves this by pre-shifting its bandpass, ensuring the 500.7nm O-III line remains perfectly centered when used with systems from f\/2 to f\/3.5. This makes it an essential tool for instruments like Celestron RASA, Starizona HyperStar, and fast astrographs, where conventional filters would fail to deliver.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e6.5nm O-III for Maximum Contrast\u003c\/h3\u003e\n\u003cp\u003eWith a full width at half maximum (FWHM) of just 6.5nm, this filter delivers exceptional contrast by rejecting unwanted light from streetlights, moonlight, and atmospheric airglow. This narrow window dramatically darkens the sky background, making faint, extended structures in O-III rich targets like the Veil Nebula (NGC 6960) or the Dumbbell Nebula (M27) stand out with striking clarity. The high transmission within this narrow band ensures that exposure times remain manageable while detail is maximized.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCMOS-Optimized in Every Format\u003c\/h3\u003e\n\u003cp\u003eModern CMOS sensors are highly reflective, often causing halos and internal reflections with traditional filters. Every size of this Baader Highspeed filter features advanced anti-reflection coatings, including Baader's Reflex-Blocker™ technology, to virtually eliminate these artifacts, even with bright stars in the field of view – from small sensors behind a 1.25\" filter to full-frame and medium-format sensors that call for the large square formats. Additionally, Baader's Life-Coat™ technology provides a hardened, sealed coating edge, protecting the filter from moisture intrusion and aging for a lifetime of reliable use.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eBaader f\/2 Highspeed vs. Standard Narrowband Filters\u003c\/h3\u003e\n\u003cp\u003eThe choice between a Highspeed filter and a standard narrowband filter is determined entirely by your telescope's focal ratio. A standard filter is designed for peak transmission at f\/4 or slower, while this Highspeed version is specifically built for the f\/2 to f\/3.5 range.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard O-III Filter at f\/2:\u003c\/strong\u003e Experiences significant bandpass shift. The filter's transmission peak moves off the O-III emission line, resulting in a dim, low-contrast image.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBaader f\/2 Highspeed O-III Filter at f\/2:\u003c\/strong\u003e The pre-shifted bandpass is perfectly aligned to the O-III line at this focal ratio, guaranteeing the highest possible signal and contrast from your fast optical system.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat makes the Baader 6.5nm O-III filter \"Highspeed\"?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA \"Highspeed\" filter is specifically designed for telescopes with very fast focal ratios, such as f\/2 or f\/3. Its coatings are engineered to be \"pre-shifted,\" which compensates for the blue-shift that occurs when light passes through a filter at a steep angle. This ensures the \u003cstrong\u003e6.5nm\u003c\/strong\u003e bandpass remains centered on the O-III emission line for maximum signal transmission on fast optics.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use this Baader f\/2 Highspeed filter with a slower telescope like an f\/8 refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile it will work, it is not ideal. The pre-shifted bandpass that is perfect for an \u003cstrong\u003ef\/2\u003c\/strong\u003e system will be off-wavelength on an f\/8 system, leading to reduced light transmission. For telescopes f\/4 and slower, a standard Baader CMOS-optimized narrowband filter is the correct choice.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhich size of the Baader O-III f\/2 Highspeed-Filter fits my filter wheel or drawer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e1.25\"\u003c\/strong\u003e and \u003cstrong\u003e2\"\u003c\/strong\u003e versions come in mounted cells for standard threaded filter holders and wheels. The \u003cstrong\u003e2\" unmounted (Ø 47.4mm)\u003c\/strong\u003e filter is designed for the Baader FCCT (Filter Changer Camera Tilter) and will not thread into a standard 2\" (M48) carousel. The \u003cstrong\u003e31mm\u003c\/strong\u003e, \u003cstrong\u003e36mm\u003c\/strong\u003e and \u003cstrong\u003e50.4mm\u003c\/strong\u003e unmounted round filters fit wheels that accept those sizes, such as models from ZWO, QHY or Atik, while the \u003cstrong\u003e50x50mm\u003c\/strong\u003e and \u003cstrong\u003e65x65mm\u003c\/strong\u003e squares suit filter wheels and drawers for large full-frame and medium-format sensors. Always confirm the accepted filter size in your wheel's documentation.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Baader 6.5nm O-III Highspeed filter work well for imaging the Veil Nebula (NGC 6960) with a Celestron RASA 8?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, this is a perfect combination. The Celestron RASA 8 operates at \u003cstrong\u003ef\/2\u003c\/strong\u003e, making it the exact type of instrument this filter was designed for. The Veil Nebula is extremely rich in O-III emission, and the \u003cstrong\u003e6.5nm\u003c\/strong\u003e bandpass will provide exceptional contrast, revealing its intricate filamentary structure against a dark sky background.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eI have a fast f\/3.8 Newtonian. Is the Baader f\/2 Highspeed filter a better choice than a standard O-III filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. While an f\/3.8 system is on the edge of the recommended range, the Highspeed filter is still the superior choice. A standard filter designed for f\/4 and slower systems would already show some signal loss due to bandpass shift at f\/3.8. The \u003cstrong\u003ef\/2 Highspeed filter\u003c\/strong\u003e is designed for the f\/2 to f\/3.5 range but will still outperform a standard filter at f\/3.8.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the advantage of a 6.5nm bandpass on the Baader O-III filter compared to wider filters?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA narrower bandpass like \u003cstrong\u003e6.5nm\u003c\/strong\u003e provides significantly better rejection of light pollution and natural skyglow compared to wider 10nm or 12nm filters. This leads to a darker sky background and higher contrast in your final image, making faint nebular details more visible, especially from urban or suburban locations.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eSingle Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Usage\u003c\/td\u003e\n\u003ctd\u003eCMOS, CCD, O-III\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCWL (Central Wavelength)\u003c\/td\u003e\n\u003ctd\u003e500.7 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e1.25\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III (Oxygen-III) Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\" Mounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDesign Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5 High-Speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized For\u003c\/td\u003e\n\u003ctd\u003eCMOS Sensors\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003eOptically Polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Unmounted Filter (Ø 47.4mm, FCCT)\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III (Oxygen-III)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDesign Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 High-Speed Systems\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e47.4 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompatibility\u003c\/td\u003e\n\u003ctd\u003eDesigned for Baader FCCT Systems\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e47.4 mm (2\" w\/o cell)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e31mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e31mm, Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2.3 to f\/3.4 (centered at f\/2)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, CMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003eOptically Polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e36mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSeries\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50.4mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eNarrowband Interference Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEmission Line\u003c\/td\u003e\n\u003ctd\u003eO-III (Oxygen-III)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50.4mm (Unmounted)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50x50mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eNarrowband O-III (Doubly Ionized Oxygen)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50mm x 50mm (unmounted)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker, Life-Coat Hard Coatings\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.02\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e50 x 50 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003esquare\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eWavelength\u003c\/td\u003e\n\u003ctd\u003eO-III (Oxygen-III)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e65mm x 65mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized, Reflex-Blocker, Life-Coat\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003eOptically Polished Glass\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.03\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e65 x 65 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader O-III f\/2 Highspeed-Filter (6.5nm), selected size\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eProtective Filter Case or Storage Box (packaging varies by size)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Filter_Problems_FAQ_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Filter Problems FAQ Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Cleaning_and_Maintenance_of_Optics_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Cleaning and Maintenance of Optics Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Narrowband_Filters_on_Astronomical_Telescopes_Whitepaper.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Narrowband Filters on Astronomical Telescopes Whitepaper\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_We_Found_the_Way_Presentation_by_Christoph_Kaltseis.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium We Found the Way Presentation by Christoph Kaltseis\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_FCCT_Filter_Changer_Camera_Tilter_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium FCCT Filter Changer Camera Tilter Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium Warranty Policy\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"1.25\" Round Mounted","offer_id":52913186242845,"sku":"BAA-2961225","price":232.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Mounted","offer_id":52913186275613,"sku":"BAA-2961228","price":380.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Unmounted Filter (Ø 47.4mm, FCCT)","offer_id":52913186308381,"sku":"BAA-2961228U","price":332.0,"currency_code":"CAD","in_stock":true},{"title":"31mm Round Unmounted Filter","offer_id":52913186341149,"sku":"BAA-2961226","price":247.0,"currency_code":"CAD","in_stock":true},{"title":"36mm Round Unmounted Filter","offer_id":52913186373917,"sku":"BAA-2961227","price":271.0,"currency_code":"CAD","in_stock":true},{"title":"50.4mm Round Unmounted Filter","offer_id":52913186406685,"sku":"BAA-2961229","price":395.0,"currency_code":"CAD","in_stock":true},{"title":"50x50mm Square Filter","offer_id":52913186439453,"sku":"BAA-2961230","price":452.0,"currency_code":"CAD","in_stock":true},{"title":"65x65mm Square Filter","offer_id":52913186472221,"sku":"BAA-2961231","price":565.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-Baader-O-III-1-f-2-Highspeed-Filter-6-5nm-CMOS-optimized-1_baa9ffc5-a9cb-48a3-b3a2-54fd060e2109.jpg?v=1789087563"},{"product_id":"baader-planetarium-o-iii-f2-ultra-highspeed-filter-4nm-cmos-optimized","title":"Baader Planetarium O-III f\/2 Ultra-Highspeed-Filter (4nm) – CMOS-optimized","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e4nm FWHM Bandpass\u003c\/li\u003e\n\u003cli\u003eOptimized for f\/2 Ultra-Highspeed Systems\u003c\/li\u003e\n\u003cli\u003eAvailable in 1.25\" \u0026amp; 2\" Mounted, 31mm, 36mm, 47.4mm (FCCT) \u0026amp; 50.4mm Round Unmounted, and 50x50mm \u0026amp; 65x65mm Square Sizes\u003c\/li\u003e\n\u003cli\u003eCMOS-Optimized Anti-Reflection and Halo Coatings\u003c\/li\u003e\n\u003cli\u003eReflex-Blocker™ Hard-Coated and Polished\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section-center\"\u003e\n      \u003ch2\u003eBaader O-III f\/2 Ultra-Highspeed-Filter (4nm) – CMOS-optimized\u003c\/h2\u003e\n      \u003cp\u003eThe Baader O-III f\/2 Ultra-Highspeed Filter is specifically engineered to operate without bandpass shift on ultra-fast astrographs, delivering its full 4nm contrast even at focal ratios down to f\/2. Standard narrowband filters suffer a blue-shift when used on fast optics, reducing transmission and contrast, but this filter's pre-shifted design – offered in mounted 1.25\" and 2\" cells, as unmounted 31mm, 36mm and 50.4mm rounds, as a 47.4mm unmounted version for the Baader FCCT, and as 50x50mm and 65x65mm squares – ensures peak O-III signal capture where others fail.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eEngineered for f\/2 Systems: Zero Bandpass Shift\u003c\/h3\u003e\n      \u003cp\u003eThe primary challenge of narrowband imaging with fast optical systems like a RASA, HyperStar, or fast refractor is bandpass shift. A standard filter designed for f\/5 or slower will have its transmission window shift towards the blue when faced with the steep light cone of an f\/2 system, effectively de-tuning it from the target 500.7nm O-III emission line. Baader's f\/2 Ultra-Highspeed filters solve this by intentionally pre-shifting the bandpass, ensuring it lands squarely on the O-III line at its design focal ratio for maximum signal throughput.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n    \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eThe 4nm Advantage in Light-Polluted Skies\u003c\/h3\u003e\n      \u003cp\u003eWith a full-width at half-maximum (FWHM) of just 4nm, this filter provides an extremely high degree of contrast against background light pollution and natural skyglow. This narrow window isolates the faint, doubly ionized oxygen signal from emission nebulae like the Veil Nebula (NGC 6960) or the Crescent Nebula (NGC 6888) with exceptional clarity. The result is a darker background sky and more prominent nebulosity, even from suburban locations.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n        \u003ch3\u003eCMOS-Optimized Coatings for Halo-Free Imaging\u003c\/h3\u003e\n        \u003cp\u003eModern CMOS sensors are highly reflective, especially to near-infrared light, which can cause halos around bright stars. Baader addresses this with advanced CMOS-optimized coatings that provide superb anti-reflection properties. These Reflex-Blocker™ coatings, combined with planeoptically polished surfaces, ensure that stars remain tight and free of distracting internal reflections, preserving the quality of your data across the entire field – from a small sensor behind a 1.25\" filter to full-frame and larger chips behind the square formats.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eBaader 4nm f\/2 vs. 7nm Filters: Speed vs. Signal Strength\u003c\/h3\u003e\n      \u003cp\u003eChoosing between a 4nm and a wider 6.5nm or 7nm filter involves a direct trade-off. The 4nm f\/2 filter is the superior choice for maximum contrast under light-polluted skies or for separating fine structural details in bright nebulae. However, a wider filter may be preferable for very faint targets or when imaging under pristine dark skies, as it captures more signal and is more forgiving with slight guide errors or temperature shifts.\u003c\/p\u003e\n      \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eBaader 4nm f\/2 Filter:\u003c\/strong\u003e Unmatched contrast for light-polluted environments and high-detail imaging on ultra-fast systems around f\/2. It requires precise guiding and focus.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eStandard 7nm Filter:\u003c\/strong\u003e Gathers more total photons, making it better suited for extremely faint, low-surface-brightness objects. It is also less demanding on the imaging setup and works best on systems slower than f\/4.\u003c\/li\u003e\n      \u003c\/ul\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhy do I need a special Baader f\/2 filter for my RASA or HyperStar system?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eStandard narrowband filters experience \"bandpass shift\" when used with very fast optical systems like a Celestron RASA or a HyperStar-equipped SCT. The steep angle of incoming light effectively shifts the filter's transmission window, causing it to miss the target O-III emission line. The \u003cstrong\u003eBaader f\/2 Ultra-Highspeed Filter\u003c\/strong\u003e is pre-shifted to counteract this effect, ensuring you get maximum signal and contrast at ultra-fast focal ratios around f\/2.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWill this Baader 4nm O-III filter work well on my f\/7 refractor?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eNo, this filter is not recommended for slower telescopes. Because it is intentionally pre-shifted for ultra-fast optics around f\/2, using it on an f\/7 refractor will result in the bandpass being off-target, leading to significantly reduced light transmission. For f\/4 or slower systems, you should use Baader's standard narrowband filters (e.g., the 6.5nm CMOS-optimized versions).\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhich size of the Baader O-III f\/2 Ultra-Highspeed Filter do I need?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eChoose the size that matches your filter holder and sensor. The \u003cstrong\u003e1.25\"\u003c\/strong\u003e (M28.5 x 0.6 thread) and \u003cstrong\u003e2\"\u003c\/strong\u003e versions are mounted for standard threaded filter wheels and holders. The \u003cstrong\u003e2\" unmounted (Ø 47.4mm)\u003c\/strong\u003e filter is designed for the Baader FCCT (Filter Changer Camera Tilter) and compatible filter drawers, not for standard 2\" threaded wheels. The \u003cstrong\u003e31mm\u003c\/strong\u003e, \u003cstrong\u003e36mm\u003c\/strong\u003e and \u003cstrong\u003e50.4mm\u003c\/strong\u003e unmounted rounds fit wheels and drawers that accept those sizes, while the \u003cstrong\u003e50x50mm\u003c\/strong\u003e square covers full-frame sensors such as the ZWO ASI6200MM and the \u003cstrong\u003e65x65mm\u003c\/strong\u003e square is intended for large-format sensors with a 40mm diagonal or greater.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the 4nm bandpass on this Baader filter affect my images?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eA narrower \u003cstrong\u003e4nm bandpass\u003c\/strong\u003e provides higher contrast than wider 6.5nm or 7nm filters by rejecting more unwanted light from skyglow and light pollution. This makes faint nebular details stand out more dramatically against a darker sky background. The trade-off is that it requires longer total integration times to achieve the same signal level as a wider filter.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eIs the Baader O-III f\/2 filter parfocal with other Baader filters?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes, all Baader filters within a given size and series are designed to be parfocal. This means you should not need to significantly refocus when switching between different Baader LRGB or narrowband filters of the same size in your filter wheel, saving valuable imaging time.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use this 4nm O-III filter for visual observing?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eWhile technically possible, it is not practical. A 4nm bandpass is extremely restrictive and will result in a very dim image, even on large-aperture telescopes. This filter is designed exclusively for long-exposure astrophotography. For visual use, a much wider O-III filter is recommended.\u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eSingle Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Usage\u003c\/td\u003e\n\u003ctd\u003eCMOS, CCD, O-III\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCWL (Central Wavelength)\u003c\/td\u003e\n\u003ctd\u003e500.7 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e1.25\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Size\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eNarrowband O-III\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDesign Focal Ratio\u003c\/td\u003e\n\u003ctd\u003eOptimized for f\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThreads\u003c\/td\u003e\n\u003ctd\u003eM28.5 x 0.6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized Reflex-Blocker™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003ePlaneoptically Polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Unmounted Filter (Ø 47.4mm, FCCT)\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/1.8 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e47.4 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003eOptically Polished Glass\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Quality\u003c\/td\u003e\n\u003ctd\u003e1\/4 Wavefront\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApplication\u003c\/td\u003e\n\u003ctd\u003eBaader FCCT, Filter Drawers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e47.4 mm (2\" w\/o cell)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e31mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III (Oxygen-III) Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e31mm, Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/1.8 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized, Phantom Group Anti-Reflection\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003ePlanoptically Polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Narrowband O-III\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e36mm Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized F-Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApplication\u003c\/td\u003e\n\u003ctd\u003eAstrophotography\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker, CMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50.4mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50.4mm (Unmounted)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50x50mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50mm x 50mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.02\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e50 x 50 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003esquare\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/2 Ultra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e4 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eO-III\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III Ultra-Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e65mm x 65mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.03\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e65 x 65 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cul class=\"DAV-grid\"\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eBaader O-III f\/2 Ultra-Highspeed-Filter (4nm), selected size\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eFilter Case (where supplied; packaging varies by size)\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Filter_Problems_FAQ_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Filter Problems FAQ Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Cleaning_and_Maintenance_of_Optics_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Cleaning and Maintenance of Optics Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Narrowband_Filters_on_Astronomical_Telescopes_Whitepaper.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Narrowband Filters on Astronomical Telescopes Whitepaper\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_We_Found_the_Way_Presentation_by_Christoph_Kaltseis.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium We Found the Way Presentation by Christoph Kaltseis\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_FCCT_Filter_Changer_Camera_Tilter_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium FCCT Filter Changer Camera Tilter Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"1.25\" Round Mounted","offer_id":52913188569373,"sku":"BAA-2961450","price":395.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Mounted","offer_id":52913188602141,"sku":"BAA-2961453","price":562.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Unmounted Filter (Ø 47.4mm, FCCT)","offer_id":52913188634909,"sku":"BAA-2961453U","price":501.0,"currency_code":"CAD","in_stock":true},{"title":"31mm Round Unmounted Filter","offer_id":52913188667677,"sku":"BAA-2961451","price":421.0,"currency_code":"CAD","in_stock":true},{"title":"36mm Round Unmounted Filter","offer_id":52913188700445,"sku":"BAA-2961452","price":497.0,"currency_code":"CAD","in_stock":true},{"title":"50.4mm Round Unmounted Filter","offer_id":52913188733213,"sku":"BAA-2961454","price":606.0,"currency_code":"CAD","in_stock":true},{"title":"50x50mm Square Filter","offer_id":52913188765981,"sku":"BAA-2961455","price":625.0,"currency_code":"CAD","in_stock":true},{"title":"65x65mm Square Filter","offer_id":52913188798749,"sku":"BAA-2961456","price":829.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-Baader-O-III-1-f-2-Ultra-Highspeed-Filter-4nm-CMOS-optimized-1_f4bdc8f4-3ca5-4e38-9a28-f0b63bbbf4a0.jpg?v=1789087634"},{"product_id":"baader-planetarium-o-iii-f3-ultra-highspeed-filter-4nm-cmos-optimized","title":"Baader Planetarium O-III f\/3 Ultra-Highspeed-Filter (4nm) – CMOS-optimized","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e4nm FWHM Ultra-Narrow Bandpass\u003c\/li\u003e\n\u003cli\u003eOptimized for f\/3 and Faster Optical Systems\u003c\/li\u003e\n\u003cli\u003eAvailable in 1.25\" \u0026amp; 2\" Mounted, 31mm, 36mm \u0026amp; 50.4mm Round Unmounted, and 50x50mm \u0026amp; 65x65mm Square Sizes\u003c\/li\u003e\n\u003cli\u003eCMOS-Optimized with Reflex-Blocker™ Coatings\u003c\/li\u003e\n\u003cli\u003eLife-Coat™ Hard Coatings for Durability\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eBaader O-III f\/3 Ultra-Highspeed-Filter (4nm) – CMOS-optimized\u003c\/h2\u003e\n\u003cp\u003eThe Baader O-III f\/3 Ultra-Highspeed Filter isolates the critical 500.7nm Oxygen-III emission line with an extremely narrow 4nm bandpass. Offered as mounted 1.25\" and 2\" filters, as 31mm, 36mm and 50.4mm unmounted rounds, and as 50x50mm and 65x65mm squares for large sensors, this advanced design is specifically pre-shifted for peak transmission on optical systems as fast as f\/3, delivering maximum contrast on faint nebulae without the signal loss caused by band-shifting in standard filters.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eA 4nm Bandpass for Extreme Contrast\u003c\/h3\u003e\n\u003cp\u003eWith a full width at half maximum (FWHM) of just 4nm, this filter provides an aggressive rejection of unwanted light pollution and background skyglow. This ultra-narrow window dramatically increases the signal-to-noise ratio, making faint, extended structures in planetary and emission nebulae stand out against a jet-black sky. The result is higher-contrast images, even from suburban locations.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eEngineered for f\/3 Systems to Prevent Band-Shift\u003c\/h3\u003e\n\u003cp\u003eStandard narrowband filters suffer from band-shift when used with very fast optics; the incoming light cone's steep angle shifts the filter's center wavelength, reducing transmission. Baader's f\/3 Ultra-Highspeed filters are pre-shifted during manufacturing to place the 4nm bandpass perfectly on the O-III line when used with fast systems around f\/3, ensuring you capture every available photon without compromise.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCMOS-Optimized Coatings for Halo-Free Imaging\u003c\/h3\u003e\n\u003cp\u003eModern CMOS sensors are highly reflective, causing halos around bright stars from light bouncing between the filter and the sensor cover glass. Every size of this Baader 4nm O-III filter features advanced Reflex-Blocker™ anti-reflection coatings to suppress these reflections. Combined with Life-Coat™ hard coatings, the filter delivers halo-free images and is built to withstand years of use and cleaning.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eBaader 4nm vs. 6.5nm O-III: When to Choose Ultra-Narrowband\u003c\/h3\u003e\n\u003cp\u003eBaader's 6.5nm O-III filter is an excellent general-purpose choice, but the 4nm Ultra-Highspeed version is a specialist tool. The primary trade-off is signal versus contrast.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBaader 6.5nm O-III:\u003c\/strong\u003e Its advantage is a wider bandpass, which gathers more signal in a given exposure time and is more forgiving with slower f-ratio telescopes. It's the workhorse for most systems f\/4 and slower.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBaader 4nm O-III f\/3:\u003c\/strong\u003e Choose this filter for its superior contrast and light pollution rejection, especially when imaging with fast systems like a RASA, HyperStar, or fast astrograph below f\/4. The tighter bandpass requires longer sub-exposures but yields a cleaner final image from challenging locations.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat makes the Baader 4nm O-III filter \"CMOS-optimized\"?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \"CMOS-optimized\" designation refers to its advanced \u003cstrong\u003eReflex-Blocker™ coatings\u003c\/strong\u003e. These coatings are designed to minimize reflections between the filter and a modern, highly reflective CMOS sensor. This drastically reduces or eliminates the halos that can appear around bright stars in narrowband images.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will this 4nm O-III filter perform on the Veil Nebula (NGC 6960) with a RASA at f\/2?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis filter is ideal for that exact scenario. A RASA or HyperStar system is faster than f\/3, where standard narrowband filters would suffer significant band-shift and signal loss. The pre-shifted design of this \u003cstrong\u003eBaader f\/3 Ultra-Highspeed filter\u003c\/strong\u003e ensures maximum transmission at f\/2, allowing you to capture the delicate, filamentary structure of the Veil Nebula (NGC 6960) with extreme contrast and short exposure times.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Baader f\/3 O-III filter on my f\/10 SCT for imaging planetary nebulae like the Ring Nebula (M57)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile it will work, it's not the optimal choice. This filter is designed for fast systems around f\/3. On an f\/10 telescope, the filter's pre-shifted bandpass will be slightly off the O-III emission line, resulting in slightly lower signal transmission. For an f\/10 SCT, you would achieve better results with one of Baader's standard (non-highspeed) narrowband O-III filters.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is band-shift and why does this f\/3 filter solve it?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003e\u003cstrong\u003eBand-shift\u003c\/strong\u003e is a physical effect where the central wavelength of an interference filter shifts toward shorter wavelengths as the angle of incoming light becomes steeper. In fast telescopes (e.g., f\/3), this steep light cone can shift a standard filter's bandpass completely off the target emission line. This Baader Ultra-Highspeed filter solves the problem by being \u003cstrong\u003eintentionally manufactured with a shifted center wavelength\u003c\/strong\u003e, so that when used at its target f-ratio of f\/3, the band-shift effect pulls it perfectly back on target.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs this Baader 4nm O-III filter suitable for visual use?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis filter is designed and optimized for astrophotography. While you can look through it, the 4nm bandpass is extremely restrictive and will result in a very dim image visually, even on bright nebulae. For visual observation, a filter with a wider bandpass, such as a 12nm or 25nm O-III, is a much better choice.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhich size of the Baader O-III f\/3 Ultra-Highspeed Filter should I choose?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eMatch the size to your filter holder and sensor. The \u003cstrong\u003e1.25\"\u003c\/strong\u003e and \u003cstrong\u003e2\"\u003c\/strong\u003e versions are mounted filters, while the \u003cstrong\u003e31mm\u003c\/strong\u003e and \u003cstrong\u003e36mm\u003c\/strong\u003e unmounted rounds are made for filter wheels that accept those sizes. The \u003cstrong\u003e50.4mm\u003c\/strong\u003e unmounted filter fits larger filter wheels from makers like ZWO, QHY and Atik, but not standard 2\" threaded filter cells. The \u003cstrong\u003e50x50mm\u003c\/strong\u003e square requires a wheel or drawer for 50mm square filters and covers full-frame sensors, and the \u003cstrong\u003e65x65mm\u003c\/strong\u003e square is intended for cameras with sensors larger than the 36x24mm full-frame format.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eSingle Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Usage\u003c\/td\u003e\n\u003ctd\u003eCMOS, CCD, O-III\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCWL (Central Wavelength)\u003c\/td\u003e\n\u003ctd\u003e500.7 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e1.25\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Narrowband O-III\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 to f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Narrowband O-III\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eMounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 to f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e2 inch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/3 Ultra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e4 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eO-III\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 to f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e31mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III (Oxygen-III)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e31mm, Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 to f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e36mm (Unmounted)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3 to f\/8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSeries\u003c\/td\u003e\n\u003ctd\u003eUltra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized, Reflex-Blocker Anti-Reflection\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 to f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50.4mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III (Emission Line)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFWHM (Bandwidth)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50.4mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 to f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50x50mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Narrowband O-III\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50mm x 50mm Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized, Anti-Reflection\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.02\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e50 x 50 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 to f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eO-III (Oxygen-III)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e65mm x 65mm Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.03\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e65 x 65 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003esquare\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/3 Ultra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e4 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eO-III\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 to f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003e1.25\" Round Mounted\u003c\/h3\u003e\n\u003cp\u003eThis product listing is for the filter only. A protective case is typically included by the manufacturer, but contents may vary.\u003c\/p\u003e\n\u003ch3\u003e31mm Round Unmounted Filter\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eO-III 31mm f\/3 Ultra-Highspeed-Filter (4nm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eFilter Storage Box\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader O-III 36mm f\/3 Ultra-Highspeed-Filter (4nm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eFilter Storage Case\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e50x50mm Square Filter\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eO-III 50x50mm f\/3 Ultra-Highspeed-Filter (4nm)\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Filter_Problems_FAQ_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Filter Problems FAQ Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Cleaning_and_Maintenance_of_Optics_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Cleaning and Maintenance of Optics Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Narrowband_Filters_on_Astronomical_Telescopes_Whitepaper.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Narrowband Filters on Astronomical Telescopes Whitepaper\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium Warranty Policy\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"1.25\" Round Mounted","offer_id":52913190535453,"sku":"BAA-2961425","price":383.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Mounted","offer_id":52913190568221,"sku":"BAA-2961428","price":561.0,"currency_code":"CAD","in_stock":true},{"title":"31mm Round Unmounted Filter","offer_id":52913190600989,"sku":"BAA-2961426","price":414.0,"currency_code":"CAD","in_stock":true},{"title":"36mm Round Unmounted Filter","offer_id":52913190633757,"sku":"BAA-2961427","price":495.0,"currency_code":"CAD","in_stock":true},{"title":"50.4mm Round Unmounted Filter","offer_id":52913190666525,"sku":"BAA-2961429","price":605.0,"currency_code":"CAD","in_stock":true},{"title":"50x50mm Square Filter","offer_id":52913190699293,"sku":"BAA-2961430","price":619.0,"currency_code":"CAD","in_stock":true},{"title":"65x65mm Square Filter","offer_id":52913190732061,"sku":"BAA-2961431","price":823.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-Baader-O-III-1-f-3-Ultra-Highspeed-Filter-4nm-CMOS-optimized-1_0d23dfdc-5deb-412f-9f49-4d3284ed04ba.jpg?v=1789087702"},{"product_id":"baader-planetarium-s-ii-f2-highspeed-filter-6-5nm-cmos-optimized","title":"Baader Planetarium S-II f\/2 Highspeed-Filter (6.5nm) – CMOS-optimized","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e6.5nm Sulfur-II Narrowband Filter\u003c\/li\u003e\n\u003cli\u003eOptimized for f\/2 High-Speed Optical Systems\u003c\/li\u003e\n\u003cli\u003eAvailable in 1.25\" \u0026amp; 2\" Mounted, 31mm, 36mm, 50.4mm \u0026amp; 2\" FCCT (Ø 47.4mm) Unmounted Round, and 50x50mm \u0026amp; 65x65mm Square Sizes\u003c\/li\u003e\n\u003cli\u003eCMOS-Optimized with Anti-Reflection Coatings\u003c\/li\u003e\n\u003cli\u003ePrevents Transmission Loss from Band-Shifting\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eBaader S-II f\/2 Highspeed-Filter (6.5nm) – CMOS-optimized\u003c\/h2\u003e\n\u003cp\u003eThe Baader S-II f\/2 Highspeed-Filter is specifically engineered for modern, fast astrographs such as RASA and HyperStar systems, delivering a tight 6.5nm bandpass without the signal loss common with standard narrowband filters on f\/2 systems. This CMOS-optimized filter isolates the critical Sulfur-II emission line, providing the high-contrast data needed for detailed bicolor or Hubble palette astrophotography, while ensuring halos and internal reflections are suppressed. It is offered in mounted 1.25\" and 2\" cells, as unmounted 31mm, 36mm and 50.4mm rounds, as a 2\" unmounted Ø 47.4mm filter for the Baader FCCT, and as 50x50mm and 65x65mm squares for large-format filter wheels and drawers.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eEngineered for f\/2 Systems to Eliminate Band-Shift\u003c\/h3\u003e\n\u003cp\u003eStandard narrowband filters suffer from band-shifting when used with very fast optics; the steep light cone angles cause the filter's central wavelength to shift, resulting in significant signal loss. Baader's f\/2 Highspeed filters solve this by pre-shifting the bandpass, ensuring peak transmission is maintained even at focal ratios as fast as f\/2. This allows you to capture maximum signal from your fast system without compromise, whichever filter size your imaging train requires.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eA 6.5nm Bandpass for Maximum Signal Contrast\u003c\/h3\u003e\n\u003cp\u003eWith a full width at half maximum (FWHM) of just 6.5nm, every size of this filter captures a very narrow slice of the spectrum centered on the 672.4nm Sulfur-II line. This tight bandpass dramatically increases the contrast between emission nebulae and the light-polluted sky background, revealing faint, intricate structures that would be lost with broader filters. The 6.5nm window is an excellent balance between high contrast and sufficient signal for shorter exposures.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCMOS-Optimized Coatings for Halo-Free Imaging\u003c\/h3\u003e\n\u003cp\u003eDesigned for the latest generation of highly sensitive CMOS sensors, this filter series incorporates advanced coatings that suppress halos and internal reflections. Baader's Reflex-Blocker™ coatings and Life-Coat™ sealed coating edges prevent stray light from bouncing between the filter and the sensor, resulting in clean, high-contrast images with tight, artifact-free stars, even when bright stars are in the field of view.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat makes the Baader 6.5nm S-II filter \"Highspeed\"?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \"Highspeed\" designation means this Baader filter is specifically designed for use with very fast optical systems, such as f\/2 Rowe-Ackermann Schmidt Astrographs (RASAs) or HyperStar-enabled SCTs. The filter's transmission band is pre-shifted to counteract the blue-shift effect that occurs with steep light cones, ensuring you get maximum signal transmission and don't lose the faint S-II signal.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use this Baader f\/2 S-II filter on my f\/8 refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis is not recommended. The filter's bandpass is pre-shifted for the steep light cones of fast systems, roughly f\/2 to f\/3.5. On a slower telescope such as an f\/8 refractor, the passband will no longer be centered on the S-II emission line, which reduces signal. For slower telescopes, a standard Baader CMOS-optimized S-II filter is the better choice.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the \"CMOS-optimized\" feature of this Baader S-II filter improve my images?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eModern CMOS sensors are highly reflective. The \"CMOS-optimized\" design incorporates advanced anti-reflection coatings (Reflex-Blocker™) that prevent light from reflecting between the filter and the sensor cover glass. This is critical for preventing halos around bright stars and reducing internal reflections that can wash out faint details in your images.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the advantage of a 6.5nm bandpass for the Baader S-II filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA \u003cstrong\u003e6.5nm bandpass\u003c\/strong\u003e offers a significant boost in contrast over wider filters by rejecting more unwanted light from skyglow and artificial light pollution. It provides a great balance, delivering very dark backgrounds and revealing faint details without being so narrow that it requires excessively long exposure times, making it ideal for most amateur imaging setups.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow would this Baader 6.5nm S-II filter perform on the Eagle Nebula (M16) with a fast astrograph?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Baader f\/2 S-II filter is an excellent choice for imaging the Eagle Nebula (M16) with a fast system like a RASA. The Pillars of Creation within M16 have strong Sulfur-II emission. This 6.5nm filter will sharply define those structures, providing high-contrast data that is essential for creating a detailed Hubble palette (SHO) image.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhich size of the Baader f\/2 S-II Highspeed filter should I choose?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eChoose the size that matches your filter wheel, drawer and sensor. The \u003cstrong\u003e1.25\" and 2\" mounted\u003c\/strong\u003e versions fit standard 1.25\" and 2\" filter holders and wheels (1.25\" is best suited to APS-C or smaller sensors), while the \u003cstrong\u003e31mm and 36mm unmounted\u003c\/strong\u003e filters fit wheels that accept those unthreaded sizes, typically used with smaller sensors (36mm is common for APS-C or smaller). The \u003cstrong\u003e2\" unmounted Ø 47.4mm\u003c\/strong\u003e version is intended for the Baader FCCT and custom filter drawers. For full-frame and larger sensors, the \u003cstrong\u003e50.4mm round\u003c\/strong\u003e, \u003cstrong\u003e50x50mm square\u003c\/strong\u003e or \u003cstrong\u003e65x65mm square\u003c\/strong\u003e formats help avoid vignetting (darkening of the corners).\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eSingle Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Usage\u003c\/td\u003e\n\u003ctd\u003eCMOS, CCD, S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCWL (Central Wavelength)\u003c\/td\u003e\n\u003ctd\u003e671.7 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e1.25\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eSulfur-II (S-II) Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e1.25\" (Round, Mounted)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e1.25 inch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eNarrowband Interference Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEmission Line\u003c\/td\u003e\n\u003ctd\u003eSulfur-II (S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\" Mounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimal Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/1.8 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003eOptically Polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Unmounted Filter (Ø 47.4mm, FCCT)\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eS-II (Sulfur-II) Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\" Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e47.4 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTechnology\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eProduct Line\u003c\/td\u003e\n\u003ctd\u003eFCCT Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e31mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eNarrowband, Sulfur-II (S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e31mm, Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAnti-Reflection Coatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDurability Coating\u003c\/td\u003e\n\u003ctd\u003eLife-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Size\u003c\/td\u003e\n\u003ctd\u003e36mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTarget Wavelength\u003c\/td\u003e\n\u003ctd\u003eS-II (Sulfur-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50.4mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eNarrowband Interference Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLine Pass\u003c\/td\u003e\n\u003ctd\u003eSulfur-II (S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50.4mm Diameter, Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker, Life-Coat\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimization\u003c\/td\u003e\n\u003ctd\u003eCMOS Sensors\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50x50mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eSulfur-II (S-II) Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50 x 50 mm (unmounted)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFWHM Bandpass\u003c\/td\u003e\n\u003ctd\u003e6.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.02\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003esquare\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eS-II Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e65x65 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e6.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.03\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader S-II f\/2 Highspeed-Filter (6.5nm), selected size\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eProtective Filter Case\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1 (where supplied with the selected size)\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Filter_Problems_FAQ_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Filter Problems FAQ Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Cleaning_and_Maintenance_of_Optics_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eCleaning and Maintenance\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Narrowband_Filters_on_Astronomical_Telescopes_Whitepaper.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Narrowband Filters on Astronomical Telescopes Whitepaper\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_We_Found_the_Way_Presentation_by_Christoph_Kaltseis.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium We Found the Way Presentation by Christoph Kaltseis\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_FCCT_Filter_Changer_Camera_Tilter_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium FCCT Filter Changer Camera Tilter Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"1.25\" Round Mounted","offer_id":52913191452957,"sku":"BAA-2961300","price":231.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Mounted","offer_id":52913191485725,"sku":"BAA-2961303","price":379.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Unmounted Filter (Ø 47.4mm, FCCT)","offer_id":52913191518493,"sku":"BAA-2961303U","price":331.0,"currency_code":"CAD","in_stock":true},{"title":"31mm Round Unmounted Filter","offer_id":52913191551261,"sku":"BAA-2961301","price":248.0,"currency_code":"CAD","in_stock":true},{"title":"36mm Round Unmounted Filter","offer_id":52913191584029,"sku":"BAA-2961302","price":273.0,"currency_code":"CAD","in_stock":true},{"title":"50.4mm Round Unmounted Filter","offer_id":52913191616797,"sku":"BAA-2961304","price":396.0,"currency_code":"CAD","in_stock":true},{"title":"50x50mm Square Filter","offer_id":52913191649565,"sku":"BAA-2961305","price":453.0,"currency_code":"CAD","in_stock":true},{"title":"65x65mm Square Filter","offer_id":52913191682333,"sku":"BAA-2961306","price":567.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-Baader-S-II-1-f-2-Highspeed-Filter-6-5nm-CMOS-optimized-1_69421a87-6363-4dca-87ec-9f28b9febbbd.jpg?v=1789087728"},{"product_id":"baader-planetarium-s-ii-f2-ultra-highspeed-filter-4nm-cmos-optimized","title":"Baader Planetarium S-II f\/2 Ultra-Highspeed-Filter (4nm) – CMOS-optimized","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e4nm FWHM Bandpass for Sulfur-II (S-II)\u003c\/li\u003e\n\u003cli\u003eEngineered for f\/2 Ultra-Highspeed Optical Systems\u003c\/li\u003e\n\u003cli\u003eAvailable in 1.25\" \u0026amp; 2\" Mounted, 31mm, 36mm, 50.4mm \u0026amp; 2\" FCCT (Ø 47.4mm) Unmounted Round, and 50x50mm \u0026amp; 65x65mm Square Sizes\u003c\/li\u003e\n\u003cli\u003eCMOS-Optimized for Halo and Reflection Suppression\u003c\/li\u003e\n\u003cli\u003ePre-Shifted Bandpass to Counteract Fast Optics\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eBaader S-II f\/2 Ultra-Highspeed-Filter (4nm) – CMOS-optimized\u003c\/h2\u003e\n\u003cp\u003eThe Baader S-II f\/2 Ultra-Highspeed Filter is engineered to solve the critical problem of bandpass shift in modern, fast astrographs, delivering maximum signal from Sulfur-II emission lines with its narrow 4nm bandpass. Standard narrowband filters suffer significant transmission loss on ultra-fast optics, but this filter's dielectric coatings are pre-shifted to ensure peak performance specifically at an f\/2 focal ratio. This optimization makes it an essential tool for imagers using RASA, HyperStar, or other ultra-fast systems with modern CMOS sensors, and it is offered in mounted 1.25\" and 2\" cells, unmounted 31mm, 36mm and 50.4mm rounds, a 2\" unmounted Ø 47.4mm FCCT version, and 50x50mm and 65x65mm squares for large-format sensors.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003ef\/2 Ultra-Highspeed Design: Preserving Signal at Extreme Focal Ratios\u003c\/h3\u003e\n\u003cp\u003eStandard narrowband filters are designed for slower optical systems, typically around f\/4 to f\/8. When used in a faster system like an f\/2 RASA, the steep light cone causes the filter's central wavelength to shift, drastically reducing transmission. Baader's f\/2 Ultra-Highspeed filters correct for this by pre-shifting the bandpass, ensuring the S-II line remains perfectly centered for maximum signal capture, preventing the data loss inherent in using mismatched filters on fast optics.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e4nm Bandpass: Maximum Contrast on Faint S-II Structures\u003c\/h3\u003e\n\u003cp\u003eWith a full width at half maximum (FWHM) of just 4nm, every size of this filter isolates the 672.4nm S-II emission line with extreme prejudice. This narrow bandpass dramatically increases contrast by rejecting more unwanted light from light pollution, moonlight, and continuum emission from stars. For faint, filamentary structures in targets like the Elephant's Trunk Nebula (IC 1396), the 4nm design darkens the sky background significantly, allowing the faint nebulosity to stand out with greater definition.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCMOS-Optimized Coatings: Eliminating Halos and Internal Reflections\u003c\/h3\u003e\n\u003cp\u003eModern CMOS sensors are notoriously more reflective than their CCD predecessors, often causing halos and reflection artifacts around bright stars. This Baader filter series is explicitly CMOS-optimized, featuring advanced anti-reflection coatings such as Baader's Reflex-Blocker™. These coatings are formulated to suppress reflections between the filter and the sensor cover glass, ensuring your final images are clean, free of distracting halos, and require less corrective post-processing.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eUltra-Highspeed f\/2 vs. Standard Narrowband Filters\u003c\/h3\u003e\n\u003cp\u003eChoosing the right filter for your telescope's focal ratio is critical for narrowband imaging. While both filter types may appear similar, their performance under different conditions is vastly different.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBaader Ultra-Highspeed f\/2 Filters:\u003c\/strong\u003e These are purpose-built for ultra-fast systems around f\/2. Their pre-shifted bandpass guarantees high transmission where standard filters fail. They are the correct choice for RASA, HyperStar, and other fast astrographs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard Narrowband Filters:\u003c\/strong\u003e These are designed for slower systems, typically f\/4 and slower. While excellent in that range, their transmission at f\/2 can drop by 50% or more, effectively crippling the light-gathering advantage of a fast telescope. Using one on a RASA is a significant mismatch that wastes valuable imaging time.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy do I need a special Baader f\/2 filter for my RASA or HyperStar?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eFast optical systems like a RASA or HyperStar produce a very steep light cone. This causes \"bandpass shift\" in standard narrowband filters, moving the filter's transmission window away from the target S-II wavelength and blocking most of your signal. The \u003cstrong\u003eBaader f\/2 Ultra-Highspeed filter\u003c\/strong\u003e is pre-shifted to be perfectly on-band at these fast focal ratios, ensuring you capture maximum light.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat happens if I use a standard S-II filter on my f\/2 telescope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYou will lose a significant amount of signal, defeating the purpose of using a fast telescope. The filter's transmission curve will shift so far that it may only pass a fraction of the S-II light. This results in faint, noisy images and much longer required exposure times, negating the primary advantage of your f\/2 system.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the 4nm bandpass on the Baader S-II filter improve images of the Wizard Nebula (NGC 7380)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Wizard Nebula has delicate S-II structures that can be washed out by starlight and light pollution. The tight \u003cstrong\u003e4nm bandpass\u003c\/strong\u003e of this Baader filter rejects this unwanted light more effectively than wider 7nm or 12nm filters. This increases contrast, darkens the sky background, and makes the faint gas clouds and filaments within the nebula much more prominent in your final image.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does \"CMOS-optimized\" mean for the Baader 4nm S-II filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt means the filter has advanced anti-reflection coatings designed to prevent halos and internal reflections that occur between the filter and a highly reflective CMOS sensor. This is critical for producing clean data without distracting artifacts around bright stars, a common issue with modern cameras.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use this Baader f\/2 Ultra-Highspeed filter on my f\/8 refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt is not recommended. Because this filter is pre-shifted for f\/2 systems, its bandpass will be off-wavelength when used at f\/8, resulting in reduced transmission. For slower telescopes, you should use Baader's standard narrowband filters, which are optimized for that focal ratio range.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhich size of the Baader S-II f\/2 Ultra-Highspeed filter should I choose?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eMatch the size to your filter holder and sensor. The \u003cstrong\u003e1.25\" and 2\" mounted\u003c\/strong\u003e filters suit standard filter wheels and holders, while \u003cstrong\u003e31mm and 36mm unmounted\u003c\/strong\u003e filters fit wheels and drawers made for those sizes, such as models from ZWO and QHY. The \u003cstrong\u003e2\" unmounted Ø 47.4mm\u003c\/strong\u003e version is intended for FCCT filter drawers and does not thread into a standard 2\" cell. For full-frame or larger sensors, choose the \u003cstrong\u003e50.4mm round\u003c\/strong\u003e, \u003cstrong\u003e50x50mm square\u003c\/strong\u003e or \u003cstrong\u003e65x65mm square\u003c\/strong\u003e format to avoid vignetting. All sizes are designed exclusively for astrophotography, not visual use.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eSingle Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Usage\u003c\/td\u003e\n\u003ctd\u003eCMOS, CCD, S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCWL (Central Wavelength)\u003c\/td\u003e\n\u003ctd\u003e671.7 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e1.25\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eNarrowband Sulfur-II (S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e1.25 inch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eNarrowband Interference Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEmission Line\u003c\/td\u003e\n\u003ctd\u003eSulfur-II (S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\" (Mounted)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRecommended Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.4\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized Anti-Reflection, Reflex-Blocker\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003eOptically Polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Unmounted Filter (Ø 47.4mm, FCCT)\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eS-II (Sulfur-II) Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e47.4 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e31mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Line\u003c\/td\u003e\n\u003ctd\u003eSulfur-II (S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFWHM Bandwidth\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e31mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDesign Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eNarrowband Sulfur-II (S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e36mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50.4mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Highspeed Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWavelength\u003c\/td\u003e\n\u003ctd\u003eSulfur-II (S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50.4mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, CMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50x50mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eNarrowband Sulfur-II (S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50mm x 50mm, unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2 to f\/3.4\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ \u0026amp; Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.02\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e50 x 50 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003esquare\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Highspeed Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEmission Line\u003c\/td\u003e\n\u003ctd\u003eSulfur-II (S-II) at 672.4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e65mm x 65mm Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker, CMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.03\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e65 x 65 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecial Features\u003c\/td\u003e\n\u003ctd\u003eCMOS-optimized with Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader S-II f\/2 Ultra-Highspeed Filter (4nm), selected size\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eFilter Storage Case\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1 (where supplied with the selected size)\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Filter_Problems_FAQ_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Filter Problems FAQ Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Cleaning_and_Maintenance_of_Optics_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Cleaning and Maintenance of Optics Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Narrowband_Filters_on_Astronomical_Telescopes_Whitepaper.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Narrowband Filters on Astronomical Telescopes Whitepaper\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_We_Found_the_Way_Presentation_by_Christoph_Kaltseis.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium We Found the Way Presentation by Christoph Kaltseis\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_FCCT_Filter_Changer_Camera_Tilter_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium FCCT Filter Changer Camera Tilter Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"1.25\" Round Mounted","offer_id":52913194369309,"sku":"BAA-2961525","price":391.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Mounted","offer_id":52913194402077,"sku":"BAA-2961528","price":578.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Unmounted Filter (Ø 47.4mm, FCCT)","offer_id":52913194434845,"sku":"BAA-2961528U","price":516.0,"currency_code":"CAD","in_stock":true},{"title":"31mm Round Unmounted Filter","offer_id":52913194467613,"sku":"BAA-2961526","price":420.0,"currency_code":"CAD","in_stock":true},{"title":"36mm Round Unmounted Filter","offer_id":52913194500381,"sku":"BAA-2961527","price":506.0,"currency_code":"CAD","in_stock":true},{"title":"50.4mm Round Unmounted Filter","offer_id":52913194533149,"sku":"BAA-2961529","price":613.0,"currency_code":"CAD","in_stock":true},{"title":"50x50mm Square Filter","offer_id":52913194565917,"sku":"BAA-2961530","price":625.0,"currency_code":"CAD","in_stock":true},{"title":"65x65mm Square Filter","offer_id":52913194598685,"sku":"BAA-2961531","price":838.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-Baader-S-II-1-f-2-Ultra-Highspeed-Filter-4nm-CMOS-optimized-1_5786f8e8-afa7-430d-9ee5-4398fdc85902.jpg?v=1789087799"},{"product_id":"baader-planetarium-s-ii-f3-ultra-highspeed-filter-4nm-cmos-optimized","title":"Baader Planetarium S-II f\/3 Ultra-Highspeed-Filter (4nm) – CMOS-optimized","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e4nm Bandwidth (FWHM)\u003c\/li\u003e\n\u003cli\u003ePre-Shifted for Fast f\/3 Optical Systems\u003c\/li\u003e\n\u003cli\u003eAvailable in 1.25\" \u0026amp; 2\" Mounted, 31mm, 36mm \u0026amp; 50.4mm Unmounted Round, and 50x50mm \u0026amp; 65x65mm Square Sizes\u003c\/li\u003e\n\u003cli\u003eCMOS-Optimized with Reflex-Blocker™ Coatings\u003c\/li\u003e\n\u003cli\u003eLife-Coat™ Hard Coatings for Durability\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eBaader S-II f\/3 Ultra-Highspeed-Filter (4nm) – CMOS-optimized\u003c\/h2\u003e\n\u003cp\u003eThe Baader S-II f\/3 Ultra-Highspeed Filter isolates the critical 672.4nm sulfur line with an extremely narrow 4nm bandpass, specifically pre-shifted to maintain peak transmission in optical systems as fast as f\/3. This CMOS-optimized design uses advanced coatings to deliver maximum signal contrast on faint emission nebulae while completely eliminating the internal reflections and halos that plague modern, highly-reflective sensors. Choose from mounted 1.25\" and 2\" (M48 x 0.75) cells, unmounted 31mm, 36mm and 50.4mm round filters, or 50x50mm and 65x65mm squares that fully illuminate full-frame and larger sensors.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eEngineered for f\/3 Systems: Zero Band-Shift Performance\u003c\/h3\u003e\n\u003cp\u003eStandard narrowband filters suffer from band-shifting when used with very fast optics; the filter's passband moves off the target emission line, crippling transmission. The Baader f\/3 Ultra-Highspeed filter solves this by pre-shifting the 4nm passband, ensuring the S-II signal remains centered in the steep light cone of a fast f\/3 system. This makes it an essential tool for instruments like RASAs, HyperStars, or fast astrographs where conventional filters fail.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eThe 4nm Advantage: Extreme Contrast for S-II Targets\u003c\/h3\u003e\n\u003cp\u003eWith a full width at half maximum (FWHM) of just 4nm, every size of this filter provides a significant contrast boost over wider 7nm or 12nm designs. This surgical isolation of the S-II line darkens the sky background, cuts through moonlight or moderate light pollution, and reveals finer, fainter structural details in targets like the Wizard Nebula (NGC 7380) or the core of the Eagle Nebula (M16).\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCMOS-Optimized Coatings for Halo-Free Stars\u003c\/h3\u003e\n\u003cp\u003eModern CMOS sensors are highly reflective, causing halos and internal reflections with improperly coated filters. This Baader filter series features Reflex-Blocker™ coatings and blackened edges to absorb off-axis light, ensuring crisp, halo-free stars. Additionally, Life-Coat™ hard coatings provide extreme durability, protecting your investment against the rigors of cleaning and use in harsh environments.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eBaader 4nm f\/3 S-II vs. 7nm S-II: A Tale of Two Speeds\u003c\/h3\u003e\n\u003cp\u003eChoosing between Baader's S-II filters depends entirely on your telescope's focal ratio. The two are not interchangeable and are designed for different optical systems.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBaader 4nm f\/3 S-II (This Filter):\u003c\/strong\u003e Its primary advantage is the pre-shifted passband for fast optics. It is the correct choice for fast astrographs such as RASAs and HyperStars. On a slow scope such as an f\/10 SCT it is not ideal, as the passband will be off-center.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard 7nm S-II Filter:\u003c\/strong\u003e Its advantage is its optimization for slower systems. It has a wider 7nm bandpass, which gathers more signal in a shorter time but offers lower contrast. It will suffer severe transmission loss on an f\/3 system due to band-shifting.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Baader 4nm f\/3 S-II filter with my f\/10 Schmidt-Cassegrain?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt is not the optimal choice. This filter is pre-shifted for fast systems. On an f\/10 telescope, the center of the passband will not be aligned with the S-II emission line, reducing transmission. A filter designed for slower f-ratios, like a standard Baader narrowband S-II filter, would be a more efficient choice for an f\/10 SCT.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will this Baader 4nm S-II filter perform on the Soul Nebula (IC 1848) with a RASA or HyperStar system?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt will perform exceptionally well. The RASA's fast optics are exactly what this filter was designed for. The pre-shifted 4nm passband will ensure you capture the maximum S-II signal from the Soul Nebula's structures, while the tight FWHM will deliver extremely high contrast, separating the faint sulfur emissions from the starfield and background sky.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does \"CMOS-optimized\" mean for the Baader 4nm f\/3 S-II filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003e\u003cstrong\u003eCMOS-optimized\u003c\/strong\u003e refers to the advanced anti-reflection coatings (Reflex-Blocker™) applied to the filter. These coatings are designed to suppress halos and internal reflections caused by the highly reflective surfaces of modern CMOS imaging sensors. This results in cleaner data with tighter, artifact-free stars, especially around bright stars within a nebula.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Baader 4nm f\/3 S-II filter require longer exposure times than a 7nm filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, all else being equal. A narrower 4nm bandpass captures less light overall (both signal and noise) compared to a 7nm filter. To achieve the same signal level, you will need to use longer sub-exposures. The trade-off is that the resulting image will have a significantly darker background and higher contrast.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the Baader 4nm f\/3 S-II filter parfocal with other Baader CMOS-optimized filters?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, Baader engineers their CMOS-optimized filters to be parfocal. When switching between the H-alpha, O-III, and S-II filters in this series using a filter wheel or drawer of the matching size, you should not need to make any significant focus adjustments, saving valuable imaging time.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the benefit of the Life-Coat™ on the Baader 4nm S-II filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003e\u003cstrong\u003eLife-Coat™\u003c\/strong\u003e is a hardened dielectric coating that makes the filter extremely scratch-resistant and durable. It allows the filter to withstand repeated cleanings and harsh environmental conditions (like high humidity) without degrading, ensuring a long operational lifetime.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eSingle Filter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Usage\u003c\/td\u003e\n\u003ctd\u003eCMOS, CCD, S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCWL (Central Wavelength)\u003c\/td\u003e\n\u003ctd\u003e671.7 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 to f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e1.25\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eSulfur-II (S-II) Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3 to f\/8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eSulfur-II (S-II) Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCentral Wavelength\u003c\/td\u003e\n\u003ctd\u003e672.4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eMounted (2\" filter cell)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThread\u003c\/td\u003e\n\u003ctd\u003eM48 x 0.75\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized (Reflex-Blocker™, Life-Coat™)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e2 inch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/3 Ultra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e4 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eS-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e31mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eS-II (Sulfur-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e31mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRecommended System Speed\u003c\/td\u003e\n\u003ctd\u003ef\/3 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Narrowband S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e36mm Round, Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDesigned Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3 and faster\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimization\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized, Reflex-Blocker™ Coatings\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50.4mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eSulfur-II (S-II) Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50.4mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted, Round\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Coverage\u003c\/td\u003e\n\u003ctd\u003eFull-frame (36 x 24mm) without vignetting\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/3 Ultra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e4 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eS-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50x50mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eSulfur-II (S-II) Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCentral Wavelength\u003c\/td\u003e\n\u003ctd\u003e672.4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50 x 50mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Compatibility\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized (Reflex-Blocker™)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.02\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e50 x 50 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003esquare\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/3 Ultra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e4 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eS-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Narrowband S-II (Sulfur-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e65mm x 65mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFormat\u003c\/td\u003e\n\u003ctd\u003eUnmounted Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3 and slower\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSensor Optimization\u003c\/td\u003e\n\u003ctd\u003eCMOS\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.03\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e65 x 65 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003e31mm Round Unmounted Filter\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eS-II 31mm f\/3 Ultra-Highspeed-Filter (4nm) – CMOS-optimized\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eS-II 36mm f\/3 Ultra-Highspeed-Filter (4nm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eFilter Storage Box\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Filter_Problems_FAQ_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Filter Problems FAQ Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Cleaning_and_Maintenance_of_Optics_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Cleaning and Maintenance of Optics Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Narrowband_Filters_on_Astronomical_Telescopes_Whitepaper.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Narrowband Filters on Astronomical Telescopes Whitepaper\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"1.25\" Round Mounted","offer_id":52913196630301,"sku":"BAA-2961500","price":392.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Mounted","offer_id":52913196663069,"sku":"BAA-2961503","price":567.0,"currency_code":"CAD","in_stock":true},{"title":"31mm Round Unmounted Filter","offer_id":52913196695837,"sku":"BAA-2961501","price":418.0,"currency_code":"CAD","in_stock":true},{"title":"36mm Round Unmounted Filter","offer_id":52913196728605,"sku":"BAA-2961502","price":501.0,"currency_code":"CAD","in_stock":true},{"title":"50.4mm Round Unmounted Filter","offer_id":52913196761373,"sku":"BAA-2961504","price":611.0,"currency_code":"CAD","in_stock":true},{"title":"50x50mm Square Filter","offer_id":52913196794141,"sku":"BAA-2961505","price":624.0,"currency_code":"CAD","in_stock":true},{"title":"65x65mm Square Filter","offer_id":52913196826909,"sku":"BAA-2961506","price":829.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-Baader-S-II-1-f-3-Ultra-Highspeed-Filter-4nm-CMOS-optimized-1_9ff61b10-5240-413a-afa5-3fc6f93ed475.jpg?v=1789087868"},{"product_id":"baader-planetarium-3-5-4nm-f3-ultra-highspeed-filter-set-cmos-optimized-h-alpha-o-iii-s-ii","title":"Baader Planetarium 3.5 \/ 4nm f\/3 Ultra-Highspeed Filter-Set – CMOS-optimized (H-alpha \/ O-III \/ S-II)","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e3.5 \/ 4nm Ultra-Narrow H-alpha, O-III \u0026amp; S-II Bandpasses\u003c\/li\u003e\n\u003cli\u003ePre-Shifted for Fast f\/3 \"Ultra-Highspeed\" Optical Systems\u003c\/li\u003e\n\u003cli\u003eCMOS-Optimized with Anti-Reflection Coatings\u003c\/li\u003e\n\u003cli\u003eAvailable in 1.25\" \u0026amp; 2\" Mounted, 31\/36\/50.4mm Round Unmounted and 50x50\/65x65mm Square Sizes\u003c\/li\u003e\n\u003cli\u003eEnables SHO \"Hubble Palette\" Astrophotography\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eBaader 3.5 \/ 4nm f\/3 Ultra-Highspeed Filter-Set – CMOS-optimized (H-alpha \/ O-III \/ S-II)\u003c\/h2\u003e\n\u003cp\u003eThis Baader Ultra-Highspeed Filter-Set combines ultra-narrow 3.5 \/ 4nm H-alpha, O-III and S-II filters, engineered specifically for the demands of modern, fast astrographs, and is available as 1.25\" or 2\" mounted filters, as 31mm, 36mm or 50.4mm round unmounted filters, or as 50x50mm or 65x65mm square filters. The entire set is optimized for systems as fast as f\/3, ensuring maximum signal capture without the internal reflections that can plague sensitive CMOS sensors. This design delivers extremely high-contrast narrowband images from even heavily light-polluted locations.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e3.5nm \/ 4nm Ultra-Narrow Bandpasses for Maximum Contrast\u003c\/h3\u003e\n\u003cp\u003eBy isolating emission lines with extremely tight 3.5 \/ 4nm bandpasses, including a 3.5nm H-alpha and a 4nm O-III filter, this filter set aggressively rejects unwanted light from urban skies, moonlight, and natural airglow. This surgical precision dramatically increases the contrast between your target nebula and the sky background. The result is a darker, cleaner background and more prominent, detailed nebulosity in your final image.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eEngineered for f\/3 Ultra-Highspeed Astrographs\u003c\/h3\u003e\n\u003cp\u003eStandard narrowband filters can suffer from band-shifting when used with very fast optical systems, causing a significant loss of signal. Baader's f\/3 Ultra-Highspeed filters are pre-shifted to place the bandpass correctly at these steep light cones, ensuring peak transmission with instruments like Celestron RASA or HyperStar systems. This specialized design is critical for maximizing signal-to-noise ratio on fast, modern telescopes.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eAdvanced Coatings for Halo-Free Imaging\u003c\/h3\u003e\n\u003cp\u003eModern CMOS sensors are highly reflective, which can cause halos and other artifacts around bright stars when using traditional filters. This Baader set is explicitly \"CMOS-optimized,\" featuring advanced coating systems designed to suppress these reflections. This ensures that bright stars like Sadr in the Cygnus region or the stars of the Trapezium in M42 remain tight, clean points of light without distracting halos.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat makes this Baader f\/3 filter set \"Ultra-Highspeed\"?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \"Ultra-Highspeed\" designation means these filters are specifically designed for the steep light cones of very fast telescopes, such as those operating at f\/3. The filter's bandpass is pre-shifted to ensure it aligns perfectly with the emission line at these focal ratios, preventing the signal loss that occurs when using standard filters on fast optics.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use these Baader f\/3 filters on a slower f\/8 SCT or f\/7 refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThese filters are optimized for fast systems around f\/3, where their pre-shifted bandpass delivers its full benefit. They can be placed in the light path of slower scopes, but the pre-shift is not needed at slower focal ratios. For dedicated slow systems such as an f\/8 SCT or f\/7 refractor, Baader's standard narrowband filters are often a better match.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the 3.5nm H-alpha filter improve my image of the Pelican Nebula (IC 5070)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Pelican Nebula is rich in H-alpha but also resides in a dense starfield of the Milky Way. A \u003cstrong\u003e3.5nm bandpass\u003c\/strong\u003e is extremely effective at isolating the nebula's faint, wispy structures from the overwhelming light of background stars and any local light pollution. This results in significantly higher contrast and reveals finer details in the dark dust lanes and ionization fronts of IC 5070.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does \"CMOS-optimized\" mean for this Baader filter set?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003e\"CMOS-optimized\" refers to the advanced anti-reflection coatings applied to the filters. Modern CMOS sensors have surfaces that are more reflective than older CCDs, which can cause halos around bright stars. These specialized coatings are designed to minimize reflections between the filter and the sensor, ensuring clean, artifact-free stars even in dense fields.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eAre the filters in the Baader 3.5\/4nm set parfocal?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eBaader Planetarium maintains very high manufacturing tolerances, and their filter sets are typically designed to be near-parfocal, meaning minimal refocusing should be needed when switching between them. However, perfect parfocal performance can depend on your specific telescope and focuser. It is always recommended to check focus after a filter change, especially when using automated imaging systems.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy is the H-alpha filter (3.5nm) narrower than the O-III filter (4nm)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIn many emission nebulae, the H-alpha signal is significantly stronger than the O-III signal. Using a tighter \u003cstrong\u003e3.5nm bandpass\u003c\/strong\u003e for H-alpha provides the maximum possible contrast and star suppression for the brightest signal layer of the image. The slightly wider \u003cstrong\u003e4nm bandpass\u003c\/strong\u003e for the weaker O-III signal helps to capture more of its faint light, balancing the signal-to-noise ratio across the channels of your SHO image.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Usage\u003c\/td\u003e\n\u003ctd\u003eCMOS, CCD, H-alpha, O-III, S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCWL (Central Wavelength)\u003c\/td\u003e\n\u003ctd\u003e656.3 nm \/ 500.7 nm \/ 671.7 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAR-Coating\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ hard coated, planeoptically polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuitable for f\/ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.4 to f\/2.3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e1.25\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Highspeed Narrowband Set (H-alpha, O-III, S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e1.25\" Mounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eH-alpha Bandpass\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eO-III Bandpass\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eS-II Bandpass\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized, Anti-Reflection\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.02\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e1.25 inch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eFilter-Set\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/3 Ultra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e3.5 nm (H-alpha) \/ 4 nm (O-III \/ S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eH-alpha \/ O-III \/ S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e2\" Round Mounted\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Highspeed Narrowband Set (H-alpha, O-III, S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2\" Mounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eH-alpha Bandpass\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eO-III Bandpass\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eS-II Bandpass\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003eOptically Polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.04\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eFilter-Set\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eMounted (LPFC 6mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e31mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Highspeed Narrowband Set (H-alpha, O-III, S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e31mm, Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eH-alpha Bandpass\u003c\/td\u003e\n\u003ctd\u003e3.5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eO-III Bandpass\u003c\/td\u003e\n\u003ctd\u003e4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompatibility\u003c\/td\u003e\n\u003ctd\u003eZWO, QHY and Atik Filter Wheels (31mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (31mm, 36mm)\u003cbr\u003e0.04 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eFilter-Set\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/3 Ultra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e3.5 nm (H-alpha) \/ 4 nm (O-III \/ S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eH-alpha \/ O-III \/ S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eNarrowband Interference Filter Set (H-alpha, O-III, S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e36 mm, Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eH-alpha Bandpass\u003c\/td\u003e\n\u003ctd\u003e3.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eO-III Bandpass\u003c\/td\u003e\n\u003ctd\u003e4 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eS-II Bandpass\u003c\/td\u003e\n\u003ctd\u003e3.5 nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3 to f\/8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™ and Life-Coat™ Hard Coatings\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003ePlaneoptically Polished\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimization\u003c\/td\u003e\n\u003ctd\u003eCMOS Sensors\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (31mm, 36mm)\u003cbr\u003e0.04 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50.4mm Round Unmounted Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Narrowband H-alpha, O-III, S-II Set\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50.4 mm, Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e3.5nm (H-alpha), 4nm (O-III, S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized Anti-Reflection\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (31mm, 36mm)\u003cbr\u003e0.04 (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e31 mm (31mm)\u003cbr\u003e36 mm (36mm)\u003cbr\u003e50.4 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003eround\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eFilter-Set\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e2 mm (31mm, 36mm)\u003cbr\u003e3 mm (50.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e50x50mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Highspeed Narrowband Set (H-alpha, O-III, S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e50x50mm, Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e3.5nm (H-alpha), 4nm (O-III, S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eReflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003ePlaneoptically Polished (1\/4-wave)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEdges\u003c\/td\u003e\n\u003ctd\u003eBlackened\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.06\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e50 x 50 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter shape\u003c\/td\u003e\n\u003ctd\u003esquare\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eFilter-Set\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter mounted\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Filter\u003c\/td\u003e\n\u003ctd\u003ef\/3 Ultra-Highspeed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHBW (Halfbandwidth)\u003c\/td\u003e\n\u003ctd\u003e3.5 nm (H-alpha) \/ 4 nm (O-III \/ S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmission Range\u003c\/td\u003e\n\u003ctd\u003eH-alpha \/ O-III \/ S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Type\u003c\/td\u003e\n\u003ctd\u003eUltra-Narrowband Emission Line\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSet Includes\u003c\/td\u003e\n\u003ctd\u003eH-alpha, O-III, S-II\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e3.5nm (H-alpha), 4nm (O-III, S-II)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e65mm x 65mm, Square\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003eUnmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptimized Focal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3 to f\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eCMOS-Optimized, Reflex-Blocker™, Life-Coat™\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eParfocal\u003c\/td\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.10\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter size\u003c\/td\u003e\n\u003ctd\u003e65 x 65 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSingle or Set?\u003c\/td\u003e\n\u003ctd\u003eFilter-Set\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness (without cell)\u003c\/td\u003e\n\u003ctd\u003e3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ch3\u003e2\" Round Mounted\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e3.5nm H-alpha Ultra-Highspeed 2\" Filter\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e4nm O-III Ultra-Highspeed 2\" Filter\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e4nm S-II Ultra-Highspeed 2\" Filter\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eIndividual Filter Cases\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 3\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e36mm Round Unmounted Filter\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e3.5nm H-alpha Ultra-Highspeed Filter (36mm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e4nm O-III Ultra-Highspeed Filter (36mm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e3.5nm S-II Ultra-Highspeed Filter (36mm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eFilter Storage Box\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e50.4mm Round Unmounted Filter\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003e3.5nm f\/3 Ultra-Highspeed H-alpha Filter (50.4mm)\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003e4nm f\/3 Ultra-Highspeed O-III Filter (50.4mm)\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003e4nm f\/3 Ultra-Highspeed S-II Filter (50.4mm)\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003ch3\u003e65x65mm Square Filter\u003c\/h3\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e3.5nm H-alpha Ultra-Highspeed Filter (65x65mm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e4nm O-III Ultra-Highspeed Filter (65x65mm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e4nm S-II Ultra-Highspeed Filter (65x65mm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Filter_Problems_FAQ_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Filter Problems FAQ Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Baader_Planetarium_Narrowband_Filters_on_Astronomical_Telescopes_Whitepaper.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBaader Planetarium Narrowband Filters on Astronomical Telescopes Whitepaper\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"1.25\" Round Mounted","offer_id":52913200169245,"sku":"BAA-2961640","price":1130.0,"currency_code":"CAD","in_stock":true},{"title":"2\" Round Mounted","offer_id":52913200202013,"sku":"BAA-2961643","price":1641.0,"currency_code":"CAD","in_stock":true},{"title":"31mm Round Unmounted Filter","offer_id":52913200234781,"sku":"BAA-2961641","price":1203.0,"currency_code":"CAD","in_stock":true},{"title":"36mm Round Unmounted Filter","offer_id":52913200267549,"sku":"BAA-2961642","price":1445.0,"currency_code":"CAD","in_stock":true},{"title":"50.4mm Round Unmounted Filter","offer_id":52913200300317,"sku":"BAA-2961644","price":1774.0,"currency_code":"CAD","in_stock":true},{"title":"50x50mm Square Filter","offer_id":52913200333085,"sku":"BAA-2961645","price":1892.0,"currency_code":"CAD","in_stock":true},{"title":"65x65mm Square Filter","offer_id":52913200365853,"sku":"BAA-2961646","price":2457.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-3-5-4nm-f-3-Ultra-Highspeed-Filter-Set-1-CMOS-optimized-H-alpha-O-III-S-II-1_7b740eea-0e2b-4ad6-a02c-38e3c67d4ee3.jpg?v=1789087964"}],"url":"https:\/\/davidastro.com\/collections\/baader-highspeed-narrowband-filters.oembed","provider":"David Astro","version":"1.0","type":"link"}