{"product_id":"optolong-h-alpha-7nm-deep-sky-filter-1","title":"Used Optolong 2\" H-Alpha 7nm Deep Sky Filter","description":"\u003cp\u003eCondition:  This is an Optolong 2\" H-Alpha 7nm filter in excellent condition.  Clean optical surfaces.  Comes in its original jewel case and box.  Normally $229 new, you save eighty bucks!  \u003cmeta charset=\"utf-8\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cspan\u003eAny dust you see in the photos is easily removable - it seems that these filters develop an electrostatic charge such that the dust in the air is just attracted to the filter.  \u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003eDescription\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eH-alpha 7nm 2\" Filter\u003c\/li\u003e\n\u003cli\u003eA very narrow emission-line filter\u003c\/li\u003e\n\u003cli\u003ePermits a 7nm bandwidth of light (focused on the 656nm wavelength) through\u003c\/li\u003e\n\u003cli\u003eBlocks transmission of contrast-killing light pollution wavelengths\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003e\u003cstrong\u003eMain Use and Performance\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cspan\u003eSuitable for viewing on faint emission nebula of H-alpha line in full moonlight or in severe light pollution.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003eHubble look of images can be made by the combination of H-alpha, OIII-CCD and SII-CCD, such as the famous “Pillars of Creation” (M16 Eagle Nebula).\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003eNarrowband imaging with SHO set (H-alpha, OIII-CCD, and SII-CCD) can be done with the moon up in heavy light pollution, so your equipment is not sitting dormant for several weeks.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003eH-alpha filter is the first narrowband addition to LRGB set for most imagers who blend a black-and-white Ha image into RGB data to enhance structural detail while maintaining natural look.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003eNarrowband filter do not eliminate the effects of light pollution or increase the object’s brightness. In many cases, they increase the contrast between nebula and night sky, but do not brighten the nebula.\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThis ultra narrowband 7 nm H-alpha filter is intended to be utilized in color filter wheels that accept 2\" filter sizes.\u003c\/p\u003e\n\u003ch5\u003eSpecifications\u003c\/h5\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cspan\u003eSurface Quality: 60\/40\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003eTransmitted Wavefront RMS: λ\/4\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003eParallelism (arcsec): 30s\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003eTechnical Data\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eSchott substrate material\u003c\/li\u003e\n\u003cli\u003eThickness 2mm\u003c\/li\u003e\n\u003cli\u003eSurface Quality: 60\/40 (Refer to MIL-O-13830)\u003c\/li\u003e\n\u003cli\u003eOptically polished to ensure accurate 1\/4 wavefront and \u0026lt;30 seconds parallelism over both surfaces\u003c\/li\u003e\n\u003cli\u003e80-percent transmission at the h-alpha line 656 nm infrared wavelength 700 to 1100 nm cut-off\u003c\/li\u003e\n\u003cli\u003e0.1-percent transmission of off-band, specifically major emission lines artificial light pollution (i.e. Na 589 nm, Hg 435 nm, and 578 nm). Transmission of 0.1-percent is equivalent to OD3 (Optical Density), where high optical density value indicates very low transmission, and low optical density indicates high transmission\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003eCWL(centre wavelength): 656.3nm\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003eFwhm: 7nm\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003eTpeak: \u0026lt;85%\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003eCoating Wavelength: 300-1100nm\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003eOptical Denisity: OD3\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eCoating Parameter\u003c\/strong\u003e\u003cbr\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eNon-cemented optical substrate coating\u003c\/li\u003e\n\u003cli\u003eElectron-beam gun evaporation with low Ion-assisted deposition coating technology for durability and resistance to scratching, as well  as stability on CWL (central wavelength); no deviation affected by temperature change\u003c\/li\u003e\n\u003cli\u003ePlanetary rotation system offers precision and homogeneity of coatings ensuring high value on transmission of pass-band and Optical density of off-band\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eFilter Cell\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eUltra-thin filter cell minimizes vignetting by maximizing possible clear aperture (clear aperture is 26mm on the 1.25\"; 45mm on the 2\")\u003c\/li\u003e\n\u003cli\u003eAero-metal Material\u003c\/li\u003e\n\u003cli\u003ePrecise CNC Machining\u003c\/li\u003e\n\u003cli\u003eSand Blasting Process\u003c\/li\u003e\n\u003cli\u003eBlack Anodized Finish\u003c\/li\u003e\n\u003cli\u003eExtinction Treatment to Prevent Reflection\u003c\/li\u003e\n\u003cli\u003eLaser Engraving No Fading\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Optolong","offers":[{"title":"2\"","offer_id":47952042524931,"sku":"U2603-BM-11302","price":150.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/b12d033b-e7fe-41c2-930d-67c9d948dbcb.jpg?v=1776470203","url":"https:\/\/milehighastro.com\/products\/optolong-h-alpha-7nm-deep-sky-filter-1","provider":"Mile High Astronomy","version":"1.0","type":"link"}