{"product_id":"svbony-sv227-h-alpha-5nm-narrowband-filter-2in","title":"SVBONY SV227 H-Alpha 5nm Narrowband Filter - 2\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eIsolates the 656.3nm H-Alpha wavelength\u003c\/li\u003e\n\u003cli\u003eAggressive 5nm Full Width at Half Maximum (FWHM) bandpass\u003c\/li\u003e\n\u003cli\u003ePeak transmittance of ≥90% for high signal throughput\u003c\/li\u003e\n\u003cli\u003eDeep ≥OD5 blocking of unwanted wavelengths from 300-1000nm\u003c\/li\u003e\n\u003cli\u003eStandard 2-inch (M48x0.75 thread) housing\u003c\/li\u003e\n\u003cli\u003e44mm clear aperture minimizes vignetting on larger sensors\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\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\u003eSVBONY SV227 2\" H-Alpha 5nm Narrowband CCD Filter\u003c\/h2\u003e\n      \u003cp\u003eThe SVBONY SV227 2\" H-Alpha 5nm Narrowband CCD Filter isolates the critical 656.3nm hydrogen-alpha emission line with a tight 5nm bandpass for maximum contrast. With peak transmittance rated at ≥90% and deep out-of-band blocking of ≥OD5 across the 300-1000nm range, this filter passes nebula signal while aggressively rejecting light pollution. The optical substrate is polished to a 1\/4λ surface parallelism, ensuring that the high resolution of your telescope is preserved in the final image.\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\u003eIsolating H-Alpha: The 5nm Bandpass at 656.3nm\u003c\/h3\u003e\n      \u003cp\u003eThe core of the SV227 is its ability to isolate a very specific slice of the red spectrum. The 5nm FWHM (Full Width at Half Maximum) is narrow enough to dramatically darken skyglow from city lights and moonlight, causing the faint structures within emission nebulae like the Heart Nebula (IC 1805) or Veil Nebula (NGC 6960) to stand out with stark contrast. Centered precisely on the 656.3nm H-alpha line, it captures the most dominant wavelength emitted by these deep-sky targets.\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\u003eOptical Integrity: ≥90% Transmission and OD5 Blocking\u003c\/h3\u003e\n      \u003cp\u003eA narrowband filter is only as good as its signal efficiency and its ability to block unwanted light. The SV227's coatings achieve a peak transmittance of ≥90%, ensuring that the faint H-alpha signal you're collecting isn't lost. Just as importantly, its ≥OD5 blocking rejects off-band light by a factor of 100,000, preventing bloated stars and washed-out backgrounds from compromising your long exposures.\u003c\/p\u003e\n        \u003cul\u003e\n            \u003cli\u003e\n\u003cstrong\u003e1\/4λ Surface Parallelism:\u003c\/strong\u003e Advanced polishing ensures the filter will not introduce distortions or degrade the sharpness of your optical system.\u003c\/li\u003e\n            \u003cli\u003e\n\u003cstrong\u003e1.85mm Substrate:\u003c\/strong\u003e The thin glass substrate helps minimize focus shift when switching between filters in a wheel.\u003c\/li\u003e\n            \u003cli\u003e\n\u003cstrong\u003eSurface Quality (60\/40):\u003c\/strong\u003e A clean, professional-grade surface finish minimizes scatter and artifacts.\u003c\/li\u003e\n        \u003c\/ul\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\u003eMechanical Design: 2-Inch Format with 44mm Clear Aperture\u003c\/h3\u003e\n      \u003cp\u003eThe SV227 is housed in a standard 2-inch cell with M48x0.75 threads, making it compatible with virtually all modern filter wheels, filter drawers, and accessories. Its generous 44mm clear aperture provides an unvignetted field for cameras with APS-C or even larger sensors, ensuring even illumination from edge to edge. The filter features a single-thread design, intended for use within a filter holder rather than for stacking directly onto other filters or eyepieces.\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\u003e5nm vs. Wider Bandwidths: Contrast and Signal Trade-offs\u003c\/h3\u003e\n      \u003cp\u003eChoosing a bandwidth is a critical decision in narrowband imaging. The SV227's 5nm bandpass offers a significant advantage over wider 7nm or 12nm filters, especially under light-polluted skies, by providing a darker background and higher contrast. While a narrower 3nm filter might offer even more contrast, it requires longer exposure times to achieve the same signal level. The 5nm design represents a highly effective balance, delivering excellent contrast without demanding excessive sub-exposure times, making it a practical choice for a wide range of telescopes and sky conditions.\u003c\/p\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\"\u003eWhat is the main advantage of the SVBONY SV227's 5nm bandwidth?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe primary advantage of the \u003cstrong\u003e5nm bandwidth\u003c\/strong\u003e is significantly higher contrast compared to wider filters (like 7nm or 12nm). It does a better job of rejecting light pollution, moonlight, and natural skyglow, making faint nebula details pop against a darker background. This is especially beneficial for imagers in suburban or urban locations.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the SV227 5nm H-Alpha filter perform on the Pelican Nebula (IC 5070) from a suburban backyard?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe SV227 is ideal for this scenario. The Pelican Nebula is rich in H-alpha emissions. From a suburban backyard, the \u003cstrong\u003e5nm bandpass\u003c\/strong\u003e will effectively isolate the nebula's 656.3nm signal from city skyglow, allowing you to capture its intricate dust lanes and bright ionization fronts with much greater clarity than you could with a broadband or wider narrowband filter.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eIs the SV227 2-inch filter a good match for a fast f\/4 Newtonian telescope?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes, but with a consideration. Fast optical systems can cause a slight \"band-shift\" in narrowband filters. While the SV227's 5nm bandpass is generally robust enough for systems down to f\/4, it offers a good balance between the contrast benefits of narrowband and tolerance for faster optics. The high ≥90% transmittance also helps gather signal efficiently in these fast systems.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does ≥OD5 blocking mean for my astrophotos with the SV227 filter?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003e\u003cstrong\u003eOD5 blocking\u003c\/strong\u003e means the filter reduces unwanted light outside its 5nm bandpass by a factor of at least 100,000. For your images, this translates to:\n    \u003c\/p\u003e\n\u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003eCleaner Backgrounds:\u003c\/strong\u003e It eliminates gradients caused by light pollution or moonlight.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eTighter Stars:\u003c\/strong\u003e It prevents halos and bloating around bright stars caused by out-of-band emissions (like near-infrared).\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eHigher Contrast:\u003c\/strong\u003e By ensuring only the desired 656.3nm light reaches the sensor, the nebula signal is maximized relative to the background noise.\u003c\/li\u003e\n    \u003c\/ul\u003e\n    \n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eThe SVBONY SV227 filter has a single M48x0.75 thread. Can I stack it with other filters?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eNo, this filter is not designed for stacking. The \u003cstrong\u003eSingle Thread: Yes\u003c\/strong\u003e specification indicates it has threads on one side only, meant for securing it into a filter wheel or filter drawer. It does not have female threads on the opposite side to attach another filter directly to it.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eIs the 1.85mm substrate thickness of the SV227 filter parfocal with other filters?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe \u003cstrong\u003e1.85mm thickness\u003c\/strong\u003e is quite thin, which helps minimize focus shift between filters. However, achieving perfect parfocal performance across an entire set of filters from different manufacturers is rare. While the SV227 is designed to be close, you should expect to make minor focus adjustments when switching between it and other filters, especially those with different substrate thicknesses.\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 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-Inch\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eCenter Wavelength (CWL)\u003c\/td\u003e\n\u003ctd\u003e656.3nm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003ePeak Transmittance\u003c\/td\u003e\n\u003ctd\u003e≥90%\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eBlocking Range\u003c\/td\u003e\n\u003ctd\u003e300-1000nm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eBlocking Depth\u003c\/td\u003e\n\u003ctd\u003e≥OD5\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eClear Aperture\u003c\/td\u003e\n\u003ctd\u003e44mm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eSubstrate Thickness\u003c\/td\u003e\n\u003ctd\u003e1.85mm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eSurface Quality\u003c\/td\u003e\n\u003ctd\u003e60\/40\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eSurface Parallelism\u003c\/td\u003e\n\u003ctd\u003e1\/4λ\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eParallelism\u003c\/td\u003e\n\u003ctd\u003e30\"\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eThread\u003c\/td\u003e\n\u003ctd\u003eM48x0.75\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eThreading\u003c\/td\u003e\n\u003ctd\u003eSingle Thread\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eNet Weight\u003c\/td\u003e\n\u003ctd\u003e12.5g \/ 0.44oz\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\"\u003eSVBONY SV227 2\" H-Alpha 5nm Filter\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\u003ca href=\"https:\/\/davidastro.com\/pages\/svbony-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eSVBONY 1-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"SVBONY","offers":[{"title":"Default Title","offer_id":52861237133597,"sku":"SV-W9187DB","price":131.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/SVBONY-SV227-2-H-Alpha-5nm-Narrowband-CCD-Filter-for-Deep-Sky-1_ab1cee9f-5a35-4f02-889e-fbc732a5f309.jpg?v=1788883673","url":"https:\/\/davidastro.com\/products\/svbony-sv227-h-alpha-5nm-narrowband-filter-2in","provider":"David Astro","version":"1.0","type":"link"}