{"product_id":"antlia-3nm-narrowband-nii-pro-filter","title":"Antlia 3nm Narrowband NII Pro Filter - 2\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eIsolates the Nitrogen-II (NII) emission line at 654.8nm\u003c\/li\u003e\n\u003cli\u003e3nm bandpass (FWHM)\u003c\/li\u003e\n\u003cli\u003e88% peak transmission\u003c\/li\u003e\n\u003cli\u003eGreater than OD5 out-of-band blocking from 300-1100nm\u003c\/li\u003e\n\u003cli\u003eUsable down to f\/3 with minimal loss of signal\u003c\/li\u003e\n\u003cli\u003eLambda\/4 or better transmitted wavefront on a 2mm thick substrate\u003c\/li\u003e\n\u003cli\u003e2\" mounted, male M48x0.75 thread\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 3nm Narrowband NII Pro Filter - 2\"\u003c\/h2\u003e\n\u003cp\u003eThe Antlia 3nm Narrowband NII Pro Filter has a 3nm bandpass centred on 654.8nm, a nitrogen-II (NII) emission wavelength, with 88% peak transmission and out-of-band blocking greater than OD5 across 300-1100nm. It is built on a single, non-glued 2mm substrate with a transmitted wavefront of Lambda\/4 or better, and the narrowband Pro filters can be used down to f\/3 with minimal loss of signal.\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\u003eIsolating the 654.8nm NII Line with a 3nm Bandpass\u003c\/h3\u003e\n\u003cp\u003eThe 3nm bandpass is centred on 654.8nm. As the bandwidth narrows, these 3nm Pro filters enhance the contrast of emission targets by reducing unwanted background signal. The filter can be used in light-polluted areas and at dark sites, and it extends imaging time when the moon is up.\u003c\/p\u003e\n\u003cp\u003eIts targets are NII emission nebulae, and the filter is only effective for deep-sky objects that contain NII emission. NII is not one of the three channels of the SII\/Ha\/OIII palette.\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\u003e88% Peak Transmission and \u0026gt;OD5 Blocking\u003c\/h3\u003e\n\u003cp\u003ePeak transmission is 88% at 654.8nm, and out-of-band blocking is rated greater than optical density (OD) 5.\u003c\/p\u003e\n\u003cp\u003eAn OD5 rating means the filter attenuates unwanted light from 300nm to 1100nm by a factor of 100,000 (transmitting only 0.001%). This ensures an excellent signal-to-noise ratio (SNR) and effective cutoff rates that minimize interference from other wavelengths.\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\u003eLambda\/4 Wavefront on a Single 2mm Substrate\u003c\/h3\u003e\n\u003cp\u003eThe filter is built on a single, non-glued 2mm optical substrate, which eliminates internal reflections. Its steep spectral profile minimizes halos around bright stars.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eTransmitted Wavefront:\u003c\/strong\u003e Lambda\/4 or better.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eParallelism:\u003c\/strong\u003e Less than 30 arcseconds.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSurface Quality:\u003c\/strong\u003e 60\/40 scratch\/dig per MIL-O-13830.\u003c\/li\u003e\n\u003c\/ul\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 Fast Optical Systems Down to f\/3\u003c\/h3\u003e\n\u003cp\u003eIn fast telescopes the steeper light cone shifts a \u003ca href=\"\/collections\/narrowband-filters\"\u003enarrowband filter\u003c\/a\u003e's central wavelength toward shorter wavelengths (blue shift). All Antlia narrowband Pro filters can be used down to f\/3 with minimal loss of signal.\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\u003eAntlia 3nm NII Pro vs. Wider Narrowband Filters\u003c\/h3\u003e\n\u003cp\u003eA 3nm band passes less skyglow and moonlight around the line than a 5nm or 7nm band, so the background is darker.\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\u003e2\" Ultra-Thin Cell with M48x0.75 Threads\u003c\/h3\u003e\n\u003cp\u003eThe 2\" cell screws in by a male M48x0.75 thread. It is ultra-thin and black anodized, with laser engraving.\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 is the Antlia 3nm NII Pro filter used for in astrophotography?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Antlia 3nm NII Pro is a specialized narrowband filter designed to capture light from the \u003cstrong\u003eNitrogen-II (NII) emission line at 654.8nm\u003c\/strong\u003e. Its targets are NII emission nebulae, and the filter is only effective for objects that contain NII emission.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the Antlia 3nm NII Pro perform in a fast telescope like an f\/4 Newtonian?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe narrowband Pro filters are \u003cstrong\u003eusable down to f\/3 with minimal loss of signal\u003c\/strong\u003e, and f\/4 is slower than that.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Antlia 3nm NII Pro filter for visual observation?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. Antlia explicitly states this filter is \u003cstrong\u003enot recommended for night visual observation\u003c\/strong\u003e. It is meant for astrophotography.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the advantage of the Antlia NII Pro's 3nm bandpass over a wider 7nm filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA 3nm band passes \u003cstrong\u003eless background light\u003c\/strong\u003e around the line than a 7nm band, so the background is darker, which matters most under light pollution or moonlight.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes the 2mm thickness of the Antlia 3nm NII Pro filter require refocusing?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Antlia 3nm NII Pro filter has a specified thickness of \u003cstrong\u003e2mm +\/- 0.05mm\u003c\/strong\u003e. Antlia makes no parfocal claim, so check focus after a filter change.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does \u0026gt;OD5 out-of-band blocking mean for the Antlia 3nm NII Pro?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eOD5 stands for Optical Density 5. It means no more than \u003cstrong\u003e0.001% of light outside the band\u003c\/strong\u003e gets through, from 300nm to 1100nm. This ensures an excellent signal-to-noise ratio.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Antlia 3nm NII Pro filter show halos around bright stars?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe steep spectral profile minimizes halos around bright stars and the \u003cstrong\u003esingle, non-glued substrate\u003c\/strong\u003e eliminates internal reflections. Very bright stars can still show some halo.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use NII data from the Antlia 3nm Pro in a standard Hubble Palette (SHO) image?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, the traditional Hubble Palette uses SII (Sulfur-II), H-alpha, and OIII (Oxygen-III) data mapped to Red, Green, and Blue, respectively. NII is a different emission line. It can serve as an additional channel in your own palette.\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 Type\u003c\/td\u003e\n\u003ctd\u003eNII Narrowband (3nm Pro series)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCentral Wavelength (CWL)\u003c\/td\u003e\n\u003ctd\u003e654.8nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandpass (FWHM)\u003c\/td\u003e\n\u003ctd\u003e3nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePeak Transmission\u003c\/td\u003e\n\u003ctd\u003e88%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOut-of-Band Blocking\u003c\/td\u003e\n\u003ctd\u003e\u0026gt;OD5 (0.001%) @ 300-1100nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRecommended f-ratio\u003c\/td\u003e\n\u003ctd\u003eUsable down to f\/3 with minimal loss of signal\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Thickness\u003c\/td\u003e\n\u003ctd\u003e2mm +\/- 0.05mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003eSingle, non-glued optical substrate\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTransmitted Wavefront\u003c\/td\u003e\n\u003ctd\u003eLambda\/4 or better\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eParallelism\u003c\/td\u003e\n\u003ctd\u003e\u0026lt; 30 arcseconds\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSurface Quality\u003c\/td\u003e\n\u003ctd\u003e60\/40 (MIL-O-13830)\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\u003eFilter Ring\u003c\/td\u003e\n\u003ctd\u003e2\" (M48x0.75), ultra-thin black anodized cell, laser engraved\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNot Recommended For\u003c\/td\u003e\n\u003ctd\u003eSolar imaging, night visual observation\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\"\u003eAntlia 3nm NII Pro filter, 2\" mounted\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 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\u003c\/li\u003e\n\n\u003cli\u003e\nAntlia 3-year warranty against delamination.\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Antlia","offers":[{"title":"2\" Mounted","offer_id":51932624486685,"sku":"ANT-NII-3NM-2","price":553.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/antlia-src-o16XY6wEw6Ac46Ac_351520aa-3a85-4077-b914-bd28499e93ed.jpg?v=1792549993","url":"https:\/\/davidastro.com\/products\/antlia-3nm-narrowband-nii-pro-filter","provider":"David Astro","version":"1.0","type":"link"}