{"product_id":"svbony-2-cls-light-pollution-filter","title":"SVBONY 2″ CLS Light Pollution Filter","description":"\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/6387037897001893449065357.jpg?v=1791669877\" alt=\"SVBONY CLS light pollution filter key visual\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe SVBONY F9155B is a 2″ CLS (City Light Suppression) filter in a standard M48 x 0.75 cell. It is a broadband light pollution filter: SVBONY specifies about 90% transmission at the main nebula emission lines (H-alpha 656 nm, OIII 496 nm, H-beta 486 nm, SII 672 nm) and about 0.1% transmission at the sodium (589 nm) and mercury (435 nm and 578 nm) lines produced by street lighting. The coated glass is 1.85 mm thick.\u003c\/p\u003e\u003cp\u003eA CLS filter does not remove light pollution or make an object brighter. It raises the contrast between nebulae and a skyglow-brightened background, which is what makes faint structure easier to see and to stretch in processing.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you image or observe from a suburban or city-edge site with a colour astronomy camera or an unmodified DSLR and want more contrast on emission nebulae. SVBONY designs it with colour CCD\/CMOS cameras and unmodified DSLRs in mind.\u003c\/p\u003e\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/f9155-2_20250807105838_0327.jpg?v=1791669878\" alt=\"SVBONY CLS light pollution filter for deep-sky imaging and observing\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eEmission lines passed:\u003c\/strong\u003e about 90% transmission at H-alpha, OIII, H-beta and SII (SVBONY figures).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStreet-light lines suppressed:\u003c\/strong\u003e about 0.1% transmission at sodium 589 nm and mercury 435\/578 nm.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHard coatings:\u003c\/strong\u003e electron-beam evaporation with ion-assisted deposition, for scratch resistance and stable performance.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEven coating:\u003c\/strong\u003e SVBONY uses a planetary rotation system in the coating chamber for consistent passbands across the glass.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard 2″ cell:\u003c\/strong\u003e M48 x 0.75 thread, 1.85 mm glass.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/6372973214719458219689724.jpg?v=1791669877\" alt=\"SVBONY CLS filter emission-line transmission and light pollution suppression panel\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eColour deep-sky imaging from light-polluted sites:\u003c\/strong\u003e emission nebulae such as M42, the Lagoon and North America Nebula.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDSLR astrophotography:\u003c\/strong\u003e with unmodified cameras through a 2″ nosepiece or filter drawer.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVisual observing:\u003c\/strong\u003e a darker background and better nebula contrast at sub-rural sites.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/f9155-3_20250807105838_1715.jpg?v=1791669878\" alt=\"SVBONY CLS light pollution filter for deep-sky imaging and observing\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread:\u003c\/strong\u003e M48 x 0.75, for 2″ barrels, diagonals, filter drawers and 2″ eyepieces.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOther sizes:\u003c\/strong\u003e SVBONY also makes this filter in 1.25″ (F9155A, M28.5 x 0.6) and as a Canon EOS-C clip-in (F9155D).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCLS vs UHC:\u003c\/strong\u003e SVBONY notes that the CLS has a wider passband than its UHC filter and suits sites with less light pollution; the UHC is the stronger choice under brighter skies.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eIf you want help choosing between CLS, UHC and a dual-band filter for your sky and camera, get in touch and we will work through it with you.\u003c\/p\u003e\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/f9155-5_20250807105838_6356.jpg?v=1791669878\" alt=\"SVBONY CLS light pollution filter for deep-sky imaging and observing\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/f9155-4_20250807105920_2311.jpg?v=1791669878\" alt=\"SVBONY CLS light pollution filter for deep-sky imaging and observing\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBroadband filters favour emission nebulae:\u003c\/strong\u003e galaxies and star clusters emit across the whole spectrum, so their gain from a CLS filter is smaller.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColour cast:\u003c\/strong\u003e as with any light pollution filter, images show a colour shift that is corrected in processing with a colour calibration step.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e SVBONY does not publish a weight for this filter.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo. It threads into any M48 x 0.75 filter thread on a 2″ nosepiece, diagonal or filter drawer.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill it work under a dark sky?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIt still passes the emission lines, but its benefit is greatest where sodium and mercury lighting brighten the background.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it work with a modified DSLR?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eSVBONY designs it for colour cameras and unmodified DSLRs. It passes H-alpha, so it also works on a modified camera.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use it for visual observing?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes. SVBONY lists both visual and photographic use.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eIn short: a 2″ M48 broadband CLS filter that suppresses sodium and mercury street-light lines while passing H-alpha, OIII, H-beta and SII, raising nebula contrast for colour imaging and observing from light-polluted skies.\u003c\/p\u003e","brand":"SvBony","offers":[{"title":"2″","offer_id":67722175021167,"sku":"F9155B","price":54.25,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/f9155-1_20250807105837_9118_20260820155328_8780.webp?v=1791669877","url":"https:\/\/ontariotelescope.com\/products\/svbony-2-cls-light-pollution-filter","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}