{"product_id":"antlia-solar-discover-5-cak-filter-assembly","title":"Antlia Solar Discover 5Å CaK Filter Assembly","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e5Å (0.5nm) Ultra-Narrow Bandpass Filter\u003c\/li\u003e\n\u003cli\u003eCentered on the 393.3nm Calcium II K-Line\u003c\/li\u003e\n\u003cli\u003e12mm Clear Aperture\u003c\/li\u003e\n\u003cli\u003eRefractors up to 100mm Aperture Without Extra Light Reduction\u003c\/li\u003e\n\u003cli\u003eOptional Antlia-Designed 2x, 3x, and 5x Barlows\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\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\u003eAntlia Solar Discover 5Å CaK Filter Assembly\u003c\/h2\u003e\n\u003cp\u003eThe Antlia Solar Discover 5Å CaK Filter Assembly incorporates a set of light-reducing filters to reduce solar heat ingress for safe operation during solar imaging, and is engineered to enhance imaging contrast of plages, light bridges, sunspots and other features prominent in the CaK 393.3nm line. Its built-in filter has a 5Å (0.5nm) FWHM centered at 393.3nm and a 12mm clear aperture. Without extra light reduction it may only be used with refractors up to 100mm aperture, and without a Barlow lens the telescope's focal ratio must be slower than f\/7.\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\u003e5Å Ultra-Narrowband Filter: Isolate the 393.3nm CaK Line\u003c\/h3\u003e\n\u003cp\u003eThe core of this assembly is its ultra-narrowband filter, featuring a 0.5nm full width at half maximum (FWHM). This level of precision isolates the specific 393.3nm CaK emission line, enabling the capture of details in the Sun's chromosphere that are not seen in white light, such as bright plages, light bridges across sunspots, and sunspots themselves.\u003c\/p\u003e\n\u003cp\u003eThe entire optical path, including the CaK filter and integrated light-reducing filters, is housed in a CNC-machined aluminum tube. The filters are assembled within a fully enclosed tube, preventing stray light from entering it.\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\u003eTelescope Requirements: Slower Than f\/7 Without a Barlow, 100mm Refractor Limit\u003c\/h3\u003e\n\u003cp\u003eThis assembly includes a set of internal light-reducing filters to reduce solar heat ingress. Antlia sets two requirements. First, if used without a Barlow lens, your telescope's focal ratio must be slower than f\/7 (f\/7 itself does not qualify). Second, without an extra light reduction solution, the assembly can only be used with refractors up to 100mm aperture.\u003c\/p\u003e\n\u003cp\u003eWith any telescope above 100mm aperture, Antlia requires additional light reduction for safe operation, such as ERF filters, solar safety films, or lowering the telescope aperture. When you use a zenith mirror, or a Barlow lens from another manufacturer, the ERF filter must be installed in the correct position shown in Antlia's installation diagram.\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\u003eOptional 2x, 3x, and 5x Barlows: Optimize Your Image Scale\u003c\/h3\u003e\n\u003cp\u003eAntlia offers dedicated 2x, 3x, and 5x Barlow lenses designed specifically for the Solar Discover 5Å CaK assembly. Antlia says the Barlow enhances detail and optimizes performance for solar photography by increasing image scale, and the f\/7 rule applies only when no Barlow is used. You can order the assembly with a Barlow pre-installed, or order the assembly and the Barlow separately.\u003c\/p\u003e\n\u003cp\u003eFor some optical trains, achieving focus with a Barlow may require more back focus. Antlia offers optional 50mm and 70mm extension tubes, ordered separately, to achieve more back focus when using a Barlow lens and help the system reach focus.\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 Dedicated Imaging Instrument: Why Visual Use is Not Recommended\u003c\/h3\u003e\n\u003cp\u003eAntlia states the Solar Discover 5Å CaK assembly is primarily used for solar imaging and is not recommended for visual observation. The 393.3nm wavelength is deep in the violet part of the spectrum and almost invisible to the human eye, and its IR coating range is slightly different from the ISO 12312-2 Standard for Solar Viewers. For tough technical requirements and safety considerations, Antlia does not recommend it for visual observation and stresses that all filters built into the assembly must be in good condition for safety.\u003c\/p\u003e\n\u003cp\u003eDisassembling the assembly is prohibited and voids the 3-year warranty, and repairs, returns and exchanges are not accepted once it has been disassembled. Antlia's transmittance requirements are a maximum of 0.0032% for UVB (280-315nm), UVA (315-380nm) and visible light (380-780nm), and a maximum of 3% in the IR from 780-1700nm (the ISO 12312-2 IR range is 780-2000nm).\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 solar features can I image with the Antlia Solar Discover 5Å CaK assembly?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis assembly is designed to capture high-contrast details in the Sun's chromosphere. Antlia engineers it to enhance imaging contrast of \u003cstrong\u003eplages\u003c\/strong\u003e (bright regions often near sunspots), \u003cstrong\u003elight bridges\u003c\/strong\u003e that form across sunspot umbrae, \u003cstrong\u003esunspots\u003c\/strong\u003e, and other features prominent in the CaK 393.3nm line.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDo I need an additional filter to use the Solar Discover 5Å CaK on my 80mm f\/7 refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAn 80mm refractor is below the \u003cstrong\u003e100mm aperture limit\u003c\/strong\u003e, so Antlia does not require extra light reduction for the aperture. But f\/7 does not meet the requirement to be \u003cstrong\u003eslower than f\/7\u003c\/strong\u003e without a Barlow, so use one of Antlia's 2X, 3X or 5X Barlow lenses. If you use a zenith mirror or another manufacturer's Barlow, the ERF filter must be installed in the correct position shown in Antlia's installation diagram.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I safely use the Antlia Solar Discover 5Å CaK assembly with my 120mm APO refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eBecause your telescope's aperture is greater than \u003cstrong\u003e100mm\u003c\/strong\u003e, Antlia requires an additional light reduction solution for safe operation, such as ERF filters, solar safety films, or lowering the telescope aperture. Without a Barlow, your telescope must also be slower than f\/7.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy is the Antlia Solar Discover 5Å CaK assembly not recommended for visual use?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe filter isolates light at \u003cstrong\u003e393.3nm\u003c\/strong\u003e, a wavelength at the extreme edge of human vision that is almost invisible to the eye. Its IR coating range also differs slightly from the ISO 12312-2 Standard for Solar Viewers, and Antlia does not recommend it for visual observation for technical and safety reasons. Use it for \u003cstrong\u003eimaging\u003c\/strong\u003e.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the purpose of the optional 2x, 3x, and 5x Barlows for the Solar Discover 5Å CaK?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Antlia-designed Barlow lenses serve two functions. First, they increase the effective focal length of your telescope, which magnifies the image for higher-resolution captures of smaller solar features. Second, without a Barlow your telescope must be slower than f\/7, so a Barlow is needed if your telescope is f\/7 or faster.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use my own Barlow lens with the Antlia Solar Discover 5Å CaK assembly?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAntlia's 2X, 3X and 5X Barlows are designed specifically for this assembly. When you use a Barlow lens supplied by another manufacturer, or a zenith mirror (star diagonal), the ERF filter must be installed in the correct position for safe operation; follow Antlia's installation diagram, and contact us if you are unsure.\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\u003eProduct Type\u003c\/td\u003e\n\u003ctd\u003eSolar imaging filter assembly (Calcium II K-line)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCentral Wavelength\u003c\/td\u003e\n\u003ctd\u003e393.3nm (CaK)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e5Å (0.5nm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eClear Aperture\u003c\/td\u003e\n\u003ctd\u003e12mm (B1200)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio Requirement\u003c\/td\u003e\n\u003ctd\u003eSlower than f\/7 (without Barlow)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTelescope Aperture Limit\u003c\/td\u003e\n\u003ctd\u003eRefractors up to 100mm without extra light reduction; above 100mm use ERF filters, solar safety film or a reduced aperture\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBarlow Options\u003c\/td\u003e\n\u003ctd\u003e2x, 3x, and 5x Antlia-designed lenses\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eVisual Use\u003c\/td\u003e\n\u003ctd\u003eNot Recommended\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eUVB Transmittance (280-315nm)\u003c\/td\u003e\n\u003ctd\u003eMax 0.0032%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eUVA Transmittance (315-380nm)\u003c\/td\u003e\n\u003ctd\u003eMax 0.0032%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eVisible Transmittance (380-780nm)\u003c\/td\u003e\n\u003ctd\u003eMax 0.0032%, Min 0.000061%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eIR Transmittance (780-1700nm)\u003c\/td\u003e\n\u003ctd\u003eMax 3%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHousing Material\u003c\/td\u003e\n\u003ctd\u003eCNC Machined Aircraft Aluminum, Oxidized\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWarranty\u003c\/td\u003e\n\u003ctd\u003e3 years (void if disassembled)\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\"\u003eSolar Discover 5Å CaK assembly\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003eBuilt-in 5Å CaK filter and light-reducing filters\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\"\u003eBarlow Lens\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003ePre-installed on 2x, 3x, and 5x Barlow options\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n3-Year Manufacturer Warranty from Antlia. Disassembly of the assembly is prohibited and voids the warranty.\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Antlia","offers":[{"title":"No Barlow","offer_id":51932625240349,"sku":"ANT-SD-CAK5A","price":880.0,"currency_code":"USD","in_stock":true},{"title":"2x Barlow","offer_id":51932627927325,"sku":"ANT-SD-CAK5A-2X","price":930.0,"currency_code":"USD","in_stock":true},{"title":"3x Barlow","offer_id":51932627960093,"sku":"ANT-SD-CAK5A-3X","price":930.0,"currency_code":"USD","in_stock":true},{"title":"5x Barlow","offer_id":51932627992861,"sku":"ANT-SD-CAK5A-5X","price":940.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/antlia-src-Yo8pPsEjC4CDi4CA_69e3e303-78a7-454a-a08e-f5557d8498b3.jpg?v=1792550005","url":"https:\/\/davidastro.com\/fr-int\/products\/antlia-solar-discover-5-cak-filter-assembly","provider":"David Astro","version":"1.0","type":"link"}