{"product_id":"optolong-oiii-filter","title":"Optolong OIII filter","description":"\u003ch2 data-start=\"42\" data-end=\"147\"\u003e\u003cstrong data-start=\"45\" data-end=\"147\"\u003eOptolong Narrowband OIII Filter – High-Contrast Oxygen-III Filter for Nebula Observation \u0026amp; Imaging\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp data-start=\"149\" data-end=\"523\"\u003eThe \u003cstrong data-start=\"153\" data-end=\"188\"\u003eOptolong Narrowband OIII Filter\u003c\/strong\u003e is a precision-engineered oxygen-III filter developed specifically for \u003cstrong data-start=\"260\" data-end=\"312\"\u003enebula observation and deep-sky astrophotography\u003c\/strong\u003e. Designed by \u003cstrong data-start=\"326\" data-end=\"367\"\u003e\u003cspan class=\"hover:entity-accent entity-underline inline cursor-pointer align-baseline\"\u003e\u003cspan class=\"whitespace-normal\"\u003eOptolong\u003c\/span\u003e\u003c\/span\u003e\u003c\/strong\u003e, this filter allows an \u003cstrong data-start=\"391\" data-end=\"436\"\u003e18nm bandwidth of light centered at 500nm\u003c\/strong\u003e to pass through—precisely matching the \u003cstrong data-start=\"476\" data-end=\"522\"\u003eOIII emission lines at 495.9nm and 500.7nm\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cp data-start=\"525\" data-end=\"1035\"\u003eBy selectively transmitting OIII wavelengths while \u003cstrong data-start=\"576\" data-end=\"632\"\u003eblocking more than 99% of artificial light pollution\u003c\/strong\u003e, including \u003cstrong data-start=\"644\" data-end=\"714\"\u003emercury vapor, high-pressure and low-pressure sodium street lights\u003c\/strong\u003e, as well as unwanted natural skyglow caused by atmospheric oxygen, the Optolong OIII filter delivers \u003cstrong data-start=\"816\" data-end=\"874\"\u003edramatically improved contrast and fine nebular detail\u003c\/strong\u003e. The result is darker skies, cleaner backgrounds, and nebula structures that stand out with exceptional clarity—even from \u003cstrong data-start=\"997\" data-end=\"1034\"\u003elight-polluted urban environments\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cp data-start=\"1037\" data-end=\"1312\"\u003ePlanetary nebulae and supernova remnants are particularly rich in OIII emissions. Many iconic deep-sky images are captured using \u003cstrong data-start=\"1166\" data-end=\"1203\"\u003eOIII and H-alpha filters together\u003c\/strong\u003e, producing results that retain \u003cstrong data-start=\"1235\" data-end=\"1311\"\u003enatural, RGB-like colors while revealing extraordinary structural detail\u003c\/strong\u003e.\u003c\/p\u003e\n\u003chr data-start=\"1314\" data-end=\"1317\"\u003e\n\u003ch2 data-start=\"1319\" data-end=\"1355\"\u003e\u003cstrong data-start=\"1322\" data-end=\"1355\"\u003eMain Applications \u0026amp; Use Cases\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cul data-start=\"1357\" data-end=\"1715\"\u003e\n\u003cli data-start=\"1357\" data-end=\"1424\"\u003e\n\u003cp data-start=\"1359\" data-end=\"1424\"\u003e✔ \u003cstrong data-start=\"1361\" data-end=\"1402\"\u003eVisual observation \u0026amp; astrophotography\u003c\/strong\u003e of emission nebulae\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1425\" data-end=\"1512\"\u003e\n\u003cp data-start=\"1427\" data-end=\"1512\"\u003e✔ Excellent for \u003cstrong data-start=\"1443\" data-end=\"1464\"\u003eplanetary nebulae\u003c\/strong\u003e and \u003cstrong data-start=\"1469\" data-end=\"1491\"\u003esupernova remnants\u003c\/strong\u003e (e.g. Veil Nebula)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1513\" data-end=\"1613\"\u003e\n\u003cp data-start=\"1515\" data-end=\"1613\"\u003e✔ Highly effective on \u003cstrong data-start=\"1537\" data-end=\"1577\"\u003ebright nebulae like M42 Orion Nebula\u003c\/strong\u003e, even under heavy light pollution\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1614\" data-end=\"1715\"\u003e\n\u003cp data-start=\"1616\" data-end=\"1715\"\u003e✔ Best used with \u003cstrong data-start=\"1633\" data-end=\"1662\"\u003elarge aperture telescopes\u003c\/strong\u003e under clear, dark skies and good seeing conditions\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cblockquote data-start=\"1717\" data-end=\"1924\"\u003e\n\u003cp data-start=\"1719\" data-end=\"1924\"\u003e\u003cstrong data-start=\"1719\" data-end=\"1738\"\u003eImportant Note:\u003c\/strong\u003e Narrowband filters do not increase the brightness of objects. Instead, they \u003cstrong data-start=\"1815\" data-end=\"1873\"\u003eincrease contrast between the nebula and the night sky\u003c\/strong\u003e, making faint details easier to observe and image.\u003c\/p\u003e\n\u003c\/blockquote\u003e\n\u003chr data-start=\"1926\" data-end=\"1929\"\u003e\n\u003ch2 data-start=\"1931\" data-end=\"1977\"\u003e\u003cstrong data-start=\"1934\" data-end=\"1977\"\u003eOptolong OIII – Optical Characteristics\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cul data-start=\"1979\" data-end=\"2331\"\u003e\n\u003cli data-start=\"1979\" data-end=\"2002\"\u003e\n\u003cp data-start=\"1981\" data-end=\"2002\"\u003e\u003cstrong data-start=\"1981\" data-end=\"1995\"\u003eBandwidth:\u003c\/strong\u003e 18nm\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2003\" data-end=\"2042\"\u003e\n\u003cp data-start=\"2005\" data-end=\"2042\"\u003e\u003cstrong data-start=\"2005\" data-end=\"2034\"\u003eCentral Wavelength (CWL):\u003c\/strong\u003e 500nm\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2043\" data-end=\"2075\"\u003e\n\u003cp data-start=\"2045\" data-end=\"2075\"\u003e\u003cstrong data-start=\"2045\" data-end=\"2059\"\u003eSubstrate:\u003c\/strong\u003e Optical glass\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2076\" data-end=\"2101\"\u003e\n\u003cp data-start=\"2078\" data-end=\"2101\"\u003e\u003cstrong data-start=\"2078\" data-end=\"2092\"\u003eThickness:\u003c\/strong\u003e 1.85mm\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2102\" data-end=\"2143\"\u003e\n\u003cp data-start=\"2104\" data-end=\"2143\"\u003e\u003cstrong data-start=\"2104\" data-end=\"2136\"\u003eAverage Transmission (Tave):\u003c\/strong\u003e \u0026gt;80%\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2144\" data-end=\"2177\"\u003e\n\u003cp data-start=\"2146\" data-end=\"2177\"\u003e\u003cstrong data-start=\"2146\" data-end=\"2165\"\u003eBlocking Range:\u003c\/strong\u003e 400–700nm\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2178\" data-end=\"2236\"\u003e\n\u003cp data-start=\"2180\" data-end=\"2236\"\u003e\u003cstrong data-start=\"2180\" data-end=\"2199\"\u003eBlocking Depth:\u003c\/strong\u003e Light pollution line blocking \u0026gt;99%\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2237\" data-end=\"2267\"\u003e\n\u003cp data-start=\"2239\" data-end=\"2267\"\u003e\u003cstrong data-start=\"2239\" data-end=\"2259\"\u003eSurface Quality:\u003c\/strong\u003e 60\/40\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2268\" data-end=\"2306\"\u003e\n\u003cp data-start=\"2270\" data-end=\"2306\"\u003e\u003cstrong data-start=\"2270\" data-end=\"2300\"\u003eTransmitted Wavefront RMS:\u003c\/strong\u003e λ\/4\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2307\" data-end=\"2331\"\u003e\n\u003cp data-start=\"2309\" data-end=\"2331\"\u003e\u003cstrong data-start=\"2309\" data-end=\"2325\"\u003eParallelism:\u003c\/strong\u003e 30s\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"2333\" data-end=\"2519\"\u003eThese specifications ensure \u003cstrong data-start=\"2361\" data-end=\"2431\"\u003eexcellent sharpness, high contrast, and minimal optical distortion\u003c\/strong\u003e, making the filter suitable for both visual observers and demanding astrophotographers.\u003c\/p\u003e\n\u003chr data-start=\"2521\" data-end=\"2524\"\u003e\n\u003ch2 data-start=\"2526\" data-end=\"2560\"\u003e\u003cstrong data-start=\"2529\" data-end=\"2560\"\u003eAdvanced Coating Technology\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp data-start=\"2562\" data-end=\"2654\"\u003eOptolong uses state-of-the-art coating processes to ensure durability and optical precision:\u003c\/p\u003e\n\u003cul data-start=\"2656\" data-end=\"3135\"\u003e\n\u003cli data-start=\"2656\" data-end=\"2733\"\u003e\n\u003cp data-start=\"2658\" data-end=\"2733\"\u003e✔ \u003cstrong data-start=\"2660\" data-end=\"2700\"\u003eMulti-layer anti-reflection coatings\u003c\/strong\u003e for maximum light transmission\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2734\" data-end=\"2806\"\u003e\n\u003cp data-start=\"2736\" data-end=\"2806\"\u003e✔ \u003cstrong data-start=\"2738\" data-end=\"2780\"\u003eNon-cemented optical substrate coating\u003c\/strong\u003e for long-term stability\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2807\" data-end=\"2906\"\u003e\n\u003cp data-start=\"2809\" data-end=\"2906\"\u003e✔ \u003cstrong data-start=\"2811\" data-end=\"2857\"\u003eIon-assisted deposition coating technology\u003c\/strong\u003e for superior scratch resistance and durability\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2907\" data-end=\"2997\"\u003e\n\u003cp data-start=\"2909\" data-end=\"2997\"\u003e✔ Stable \u003cstrong data-start=\"2918\" data-end=\"2946\"\u003ecentral wavelength (CWL)\u003c\/strong\u003e with \u003cstrong data-start=\"2952\" data-end=\"2995\"\u003eno deviation due to temperature changes\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"2998\" data-end=\"3135\"\u003e\n\u003cp data-start=\"3000\" data-end=\"3135\"\u003e✔ \u003cstrong data-start=\"3002\" data-end=\"3039\"\u003ePlanetary rotation coating system\u003c\/strong\u003e ensures coating homogeneity, high pass-band transmission, and strong off-band optical density\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"3137\" data-end=\"3140\"\u003e\n\u003ch2 data-start=\"3142\" data-end=\"3174\"\u003e⚠️ \u003cstrong data-start=\"3148\" data-end=\"3174\"\u003eWARNING – Solar Safety\u003c\/strong\u003e\n\u003c\/h2\u003e\n\u003cp data-start=\"3175\" data-end=\"3325\"\u003e\u003cstrong data-start=\"3175\" data-end=\"3235\"\u003eOptolong filters are NOT designed for solar observation.\u003c\/strong\u003e\u003cbr data-start=\"3235\" data-end=\"3238\"\u003e⚠️ \u003cstrong data-start=\"3241\" data-end=\"3325\"\u003eDO NOT look at the Sun with this filter. Doing so may cause permanent blindness.\u003c\/strong\u003e\u003c\/p\u003e\n\u003chr data-start=\"3327\" data-end=\"3330\"\u003e\n\u003ch2 data-start=\"3332\" data-end=\"3391\"\u003e\u003cstrong data-start=\"3335\" data-end=\"3391\"\u003eWhy Buy Optolong OIII Filter from Modern Telescopes?\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp data-start=\"3393\" data-end=\"3686\"\u003eBuy with confidence from \u003cstrong data-start=\"3418\" data-end=\"3500\"\u003eModern Telescopes – India’s largest and most trusted telescope selling company\u003c\/strong\u003e. We supply \u003cstrong data-start=\"3512\" data-end=\"3545\"\u003e100% genuine Optolong filters\u003c\/strong\u003e, expert technical guidance, fast pan-India shipping, and reliable after-sales support for amateur and professional astronomers across India.\u003c\/p\u003e","brand":"OPTOLONG","offers":[{"title":"1.25 Inch","offer_id":42927536635965,"sku":null,"price":7700.0,"currency_code":"INR","in_stock":true},{"title":"2 Inch","offer_id":42927536668733,"sku":null,"price":9900.0,"currency_code":"INR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0623\/6595\/8205\/files\/OptolongnarrowbandOIIIfilter1.25inch.jpg?v=1757845033","url":"https:\/\/moderntelescopes.net\/products\/optolong-oiii-filter","provider":"Modern Telescopes","version":"1.0","type":"link"}