{"product_id":"player-one-astronomy-anti-halo-pro-dual-band-2-ha-oiii-filter","title":"Player One Astronomy Anti-Halo PRO Dual-Band 2″ Ha+OIII filter","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Player One Astronomy Anti-Halo PRO Dual-Band 2″ filter isolates the two brightest emission lines in the night sky — hydrogen-alpha (Ha) at 656.3 nm and doubly ionised oxygen (OIII) at 500.7 nm — in a single 2-inch imaging filter. Its anti-halo construction suppresses the bright reflection rings that dual-band filters can throw around brilliant stars, so your emission-nebula data stays clean around the field's brightest points.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis filter is made for astrophotographers imaging emission nebulae from light-polluted skies, whether you shoot with a cooled colour (OSC) camera or a monochrome camera. If you want the Ha and OIII structure of targets like the Rosette, Veil, or North America Nebula in one exposure set while keeping stars tight and halo-free, it belongs in your imaging train.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eTrue dual-band pass:\u003c\/strong\u003e transmits Ha (656.3 nm) and OIII (500.7 nm) simultaneously, capturing the dominant red and teal nebula emissions in a single frame.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTight 3–4 nm bandwidths:\u003c\/strong\u003e a 3.7 ± 0.5 nm Ha window and a 3.2 ± 0.5 nm OIII window reject most artificial skyglow, raising contrast under heavy light pollution.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAnti-halo construction:\u003c\/strong\u003e the coating stack is engineered to eliminate the reflection halos that can surround bright stars in dual-band data.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDeep OD5 blocking:\u003c\/strong\u003e out-of-band light is blocked to optical density 5 across 200–1100 nm, keeping the passbands clean.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHigh in-band transmission:\u003c\/strong\u003e ≥85% peak transmittance preserves signal at both target lines.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard 2″ format:\u003c\/strong\u003e threads into any standard 2-inch filter cell, drawer, or filter wheel.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical\/Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe filter combines two narrow passbands on one substrate: a 3.7 ± 0.5 nm FWHM window centred on the Ha line (656.3 nm) and a 3.2 ± 0.5 nm FWHM window centred on the OIII line (500.7 nm). Peak in-band transmittance is ≥85%, while everything outside the passbands is suppressed to OD5 (optical density 5) over the full 200–1100 nm range — deep enough to hold contrast against artificial light and to keep the camera's near-infrared response from leaking through. Mechanically it is a 2-inch threaded filter; the cell measures 5 mm at the body plus a 2.5 mm thread section for a 7.5 mm total stack, and the optical glass itself is 1.85 mm thick, which matters when you budget backfocus and account for the small focus shift a filter introduces.\u003c\/p\u003e\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/Anti-Halo-PRO-2-inch-Dual-Band-filter-Curve-ZOOM3_8a443983-3448-4297-935a-960cbf8d1af1.png?v=1784237418\" alt=\"Player One Astronomy Anti-Halo PRO Dual-Band 2-inch Ha+OIII filter transmission curve showing the 656.3nm Ha and 500.7nm OIII passbands\"\u003e\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eDual-band emission-nebula imaging with OSC\/colour cameras from urban and suburban skies.\u003c\/li\u003e\n\u003cli\u003eHa and OIII data collection with monochrome cameras where a combined pass speeds acquisition.\u003c\/li\u003e\n\u003cli\u003eHigh-contrast wide-field nebula work where star halos would otherwise spoil the frame.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility \u0026amp; Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFit:\u003c\/strong\u003e standard 2″ (M48) filter threads — works in 2-inch filter drawers, filter wheels, and threaded nosepieces.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCameras:\u003c\/strong\u003e suits both one-shot-colour and monochrome astronomy cameras.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBackfocus:\u003c\/strong\u003e the 7.5 mm cell and 1.85 mm glass add to your optical path; keep them in your spacing calculation.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eThis is an imaging filter for emission nebulae; it is not intended for visual observing or for broadband targets such as galaxies and reflection nebulae.\u003c\/li\u003e\n\u003cli\u003ePlayer One does not publish a net weight for this filter, so the shipping weight shown at checkout is an estimate. Contact us if you need an exact figure.\u003c\/li\u003e\n\u003cli\u003eAs with any interference filter, introducing it shifts focus slightly, so refocus after inserting it.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eFAQ\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e No. It threads into a standard 2-inch filter holder, drawer, or wheel and needs no power or configuration; refocus once after it is in place.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill it work with my one-shot-colour camera?\u003c\/strong\u003e Yes. The dual-band design lets an OSC camera record Ha and OIII together in one exposure, which is one of the main reasons to choose this filter.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it help under light pollution?\u003c\/strong\u003e Yes. The narrow 3.2–3.7 nm passbands and OD5 blocking reject most artificial skyglow, so it is well suited to city and suburban skies.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the “anti-halo” part?\u003c\/strong\u003e The coating stack is engineered to suppress the bright reflection rings that can appear around brilliant stars in dual-band images.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Anti-Halo PRO Dual-Band 2″ Ha+OIII filter gives you clean, halo-suppressed narrowband data on emission nebulae in a single pass, with tight 3–4 nm windows and OD5 blocking that hold contrast even under heavy light pollution.\u003c\/p\u003e","brand":"Player One Astronomy","offers":[{"title":"Default Title","offer_id":44013891125359,"sku":"AHP-HO-2","price":698.6,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/Anti-Halo-PRO-2-inch-Dual-Band-filter__16630.png?v=1766565717","url":"https:\/\/ontariotelescope.com\/products\/player-one-astronomy-anti-halo-pro-dual-band-2-ha-oiii-filter","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}