{"product_id":"antlia-7nm-narrowband-sii-prime-filter","title":"Antlia 7nm Narrowband SII Prime Filter","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eCaptures Sulfur-II emission lines at a central wavelength (CWL) of 672.4nm\u003c\/li\u003e\n\u003cli\u003e7nm FWHM bandpass passes the SII lines at 671.6nm and 673.1nm\u003c\/li\u003e\n\u003cli\u003eGreater than 90% peak transmission for maximum signal strength\u003c\/li\u003e\n\u003cli\u003eOD4 (0.01%) out-of-band blocking minimizes interference from other wavelengths\u003c\/li\u003e\n\u003cli\u003eUsable with systems as fast as f\/2 with minimal loss of signal\u003c\/li\u003e\n\u003cli\u003e2mm +\/-0.05mm thick, edge blackened, single substrate\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\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 7nm Narrowband SII Prime Filter\u003c\/h2\u003e\n\u003cp\u003eThe Antlia 7nm Narrowband SII Prime Filter is centered at 672.4nm with a 7nm full width at half maximum (FWHM) bandpass that passes the Sulfur-II emission lines at 671.6nm and 673.1nm. With greater than 90% peak transmission and deep OD4 blocking of unwanted wavelengths from 300-1000nm, this filter delivers high-contrast data with an excellent signal-to-noise ratio. Built on a single, non-glued substrate with a Lambda\/4 or better transmitted wavefront, the 36mm unmounted filter can be used with nearly all systems as fast as f\/2 with minimal loss in emission 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\u003eA 7nm Bandpass with \u0026gt;90% Peak Transmission\u003c\/h3\u003e\n\u003cp\u003eThis filter centers its 7nm bandpass on 672.4nm to capture the deep red light of ionized sulfur, with high transmission at the SII emission lines at 671.6nm and 673.1nm. Antlia says this ensures maximum signal strength and well-defined nebular structures.\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\u003eOD4 Blocking and Minimized Star Halos\u003c\/h3\u003e\n\u003cp\u003eEffective narrowband imaging depends on rejecting all light outside the target wavelength. The 7nm Prime filter provides OD4 blocking, suppressing more than 99.99% of out-of-band light from 300-1000nm, which Antlia says delivers an excellent signal-to-noise ratio and better contrast, in light-polluted areas and at dark sites. The filter is built on a single, non-glued optical substrate to eliminate internal reflections, its edges are blackened against stray-light reflections, and its steep spectral profile minimizes halos around bright stars.\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\u003eSignal Integrity on Systems as Fast as f\/2\u003c\/h3\u003e\n\u003cp\u003eUsing narrowband filters on fast optical systems introduces a steep light cone that can shift a filter's bandpass. Antlia states that, with their wider FWHM, 7nm Prime filters can be used with nearly all systems as fast as f\/2 with minimal loss in emission 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 7nm Prime vs. 3nm Pro: When to Choose a Wider Bandpass\u003c\/h3\u003e\n\u003cp\u003eAntlia offers both 7nm Prime and 3nm Pro series filters, each with distinct advantages. The choice depends on your equipment and observing site.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eChoose the 7nm Prime if:\u003c\/strong\u003e You use a very fast optical system (f\/4 or faster), where the wider bandpass is more forgiving of band-shifting. It also gathers signal more quickly, which can be an advantage for shorter imaging sessions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eChoose the 3nm Pro if:\u003c\/strong\u003e Your primary goal is maximum contrast, especially from heavily light-polluted locations. The tighter bandpass rejects more background skyglow but requires longer exposure times. Antlia rates the 3nm Pro series as usable down to f\/3.\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\"\u003eShould I choose the Antlia 7nm Prime or 3nm Pro SII filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003eAntlia 7nm Prime filter\u003c\/strong\u003e suits very fast optical systems: Antlia rates it for nearly all systems as fast as f\/2, thanks to its wider FWHM. It also gathers signal faster. The 3nm Pro series offers higher contrast for imaging from light-polluted areas and is rated by Antlia as usable down to f\/3, but requires longer exposure times.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the Antlia 7nm SII filter perform on a fast f\/2 system?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAntlia states that, with their wider FWHM, 7nm Prime filters can be used with nearly all systems as fast as f\/2 with minimal loss in emission signal.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the Antlia 7nm SII filter a good choice for imaging the Elephant's Trunk Nebula (IC 1396) from the suburbs?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The Elephant's Trunk Nebula is an emission nebula with SII emission, and Antlia notes the filter can be used in light-polluted areas and dark sites. Its OD4 out-of-band blocking minimizes interference from wavelengths outside the 7nm passband, such as most streetlight emission.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy does Antlia use a single, non-glued substrate for the 7nm SII Prime filter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAntlia uses a single, non-glued substrate to eliminate internal reflections, which are a common cause of halos and other artifacts around bright stars. Antlia says this optical reliability reduces post-image processing.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the 2mm thickness of the Antlia 7nm SII filter require me to refocus?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe filter thickness is \u003cstrong\u003e2mm +\/-0.05mm\u003c\/strong\u003e for the 36mm unmounted filter, the same as the H-alpha and OIII 7nm Prime filters. Antlia does not state a parfocal specification, so check focus after changing filters.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Antlia 7nm SII Prime filter for visual observing?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. Antlia lists night visual observation as not recommended for this filter. It is designed for astrophotography of deep-sky objects that contain SII emissions.\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\u003eSII Narrowband (7nm Prime series)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAvailable Sizes\u003c\/td\u003e\n\u003ctd\u003e36mm Round Unmounted\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCentral Wavelength (CWL)\u003c\/td\u003e\n\u003ctd\u003e672.4nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFWHM (Bandpass)\u003c\/td\u003e\n\u003ctd\u003e7nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePeak Transmission\u003c\/td\u003e\n\u003ctd\u003e\u0026gt;90%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBlocking\u003c\/td\u003e\n\u003ctd\u003e\u0026gt;OD4 (0.01%) @ 300-1000nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRecommended F-Ratio\u003c\/td\u003e\n\u003ctd\u003eUsable with systems as fast as f\/2 with minimal loss of signal\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate\u003c\/td\u003e\n\u003ctd\u003eOptical, single \/ non-glued substrate\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\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 arcsec\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSurface Quality\u003c\/td\u003e\n\u003ctd\u003e60\/40 (scratch\/dig) per MIL-O-13830\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEdge Treatment\u003c\/td\u003e\n\u003ctd\u003eEdge blackened\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\n\u003cli\u003e\n3-Year Warranty against delamination.\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Antlia","offers":[{"title":"36mm Round Unmounted","offer_id":51932624617757,"sku":"ANT-SII-7NM-RD36","price":158.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/antlia-src-o8OGBwwYwoAY4oAY_4d118c05-0b8c-43d4-b575-528df1d278fd.jpg?v=1792549993","url":"https:\/\/davidastro.com\/en-int\/products\/antlia-7nm-narrowband-sii-prime-filter","provider":"David Astro","version":"1.0","type":"link"}