{"product_id":"svbony-sv227-oiii-5nm-narrowband-filter-2in","title":"SVBONY SV227 OIII 5nm Narrowband Filter - 2\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eIsolates the Oxygen III emission line at 500.7nm\u003c\/li\u003e\n\u003cli\u003eExtremely narrow 5nm Full Width at Half Maximum (FWHM) bandpass\u003c\/li\u003e\n\u003cli\u003eAchieves ≥90% peak light transmittance at the OIII line\u003c\/li\u003e\n\u003cli\u003eStandard 2-inch format with M48x0.75 filter threads\u003c\/li\u003e\n\u003cli\u003ePrecision 1.85mm thick substrate with 1\/4λ surface parallelism\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\u003cli\u003eIn the Box\u003c\/li\u003e\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\u003eSVBONY SV227 OIII 5nm 2-inch Telescope Filter\u003c\/h2\u003e\n\u003cp\u003eThe SVBONY SV227 OIII 5nm 2-inch filter is engineered to isolate the doubly ionized oxygen signal from planetary nebulae and supernova remnants with extreme prejudice. Its tight 5nm bandpass is centered precisely at the 500.7nm wavelength, achieving ≥90% peak transmittance to capture faint structures while suppressing overwhelming light pollution. The optical substrate is held to a 1\/4λ parallelism with a 60\/40 surface quality, ensuring the filter preserves the sharpness of your optical system across its full 44mm clear aperture.\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\u003eIsolate Nebulae with a 5nm FWHM Bandpass\u003c\/h3\u003e\n\u003cp\u003eThe core of the SV227 filter's imaging capability is its extremely narrow 5nm Full Width at Half Maximum (FWHM). This tight window, centered at 500.7nm, passes light almost exclusively from the OIII emission line, which is critical for revealing the delicate, glowing structures within planetary nebulae like the Dumbbell Nebula (M27) or the faint, expansive shells of supernova remnants like the Veil Nebula (NGC 6960).\u003c\/p\u003e\n\u003cp\u003eBy rejecting nearly all other wavelengths across its 300-1000nm blocking range, the filter dramatically increases contrast and allows you to pull faint details out from even heavily light-polluted skies. With a peak transmittance of ≥90%, the filter passes the maximum amount of critical signal to your sensor, keeping exposure times manageable for such a narrow bandpass.\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\u003e1\/4λ Substrate for Sharp Stars Across the Field\u003c\/h3\u003e\n\u003cp\u003eA filter is part of your optical train, and any imperfection can degrade the final image. The SV227 is built on a 1.85mm thick glass substrate polished to a 1\/4λ surface parallelism and a 60\/40 surface quality. This level of precision prevents the filter from introducing astigmatism or other distortions that can elongate stars, especially towards the edge of the field.\u003c\/p\u003e\n\u003cp\u003eThe 30\" parallelism specification ensures the two faces of the filter are almost perfectly parallel, minimizing any wedge effect that could cause image shift or focus problems when swapping between filters in a wheel. This attention to optical quality means your stars remain as tight and round as your telescope's optics can deliver.\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\u003e2-Inch Format with a 44mm Clear Aperture\u003c\/h3\u003e\n\u003cp\u003eDesigned for modern imaging setups, the SV227 comes in a standard 2-inch cell with M48x0.75 threads. This makes it directly compatible with most 2-inch filter wheels, filter drawers, and dedicated astronomy cameras. The filter provides a generous 44mm clear aperture, large enough to fully illuminate full-frame sensors without introducing vignetting from the filter cell itself.\u003c\/p\u003e\n\u003cp\u003eDespite its robust optical specifications, the filter is remarkably light, weighing only 12.5g. This low mass helps maintain the balance of your imaging train and reduces the strain on focuser motors and filter wheel mechanisms during operation.\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\u003e5nm vs. Wider OIII Filters: The Contrast Trade-Off\u003c\/h3\u003e\n\u003cp\u003eChoosing a narrowband filter involves a trade-off between contrast and exposure time. The SV227's 5nm bandpass represents a move towards higher contrast and better suppression of unwanted light.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSVBONY SV227 5nm Filter:\u003c\/strong\u003e Its primary advantage is maximum contrast. It darkens the sky background more effectively than wider filters, making it superior for pulling out the faintest details from emission nebulae, especially from urban or suburban locations. The trade-off is that it requires longer sub-exposure times to gather the same amount of signal as a wider filter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWider 7nm or 12nm Filters:\u003c\/strong\u003e These filters are more forgiving, allowing for shorter sub-exposures. However, they let in more skyglow and continuum emission from stars, resulting in a brighter background and slightly lower overall contrast on the nebula itself. They are often a good starting point, but the 5nm is the specialist's tool for difficult targets.\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\"\u003eHow will the SVBONY SV227 5nm filter perform on the Veil Nebula (NGC 6960) from a Bortle 7 zone?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe SV227 is ideal for this exact scenario. The Veil Nebula is a classic OIII-rich supernova remnant, but its faint, filamentary structure is easily lost in skyglow. The tight \u003cstrong\u003e5nm bandpass\u003c\/strong\u003e will aggressively reject the Bortle 7 light pollution, dramatically increasing contrast and making the nebula's delicate wisps stand out against a dark background.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the 1.85mm substrate thickness of the SV227 filter parfocal with other brands?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e1.85mm thickness\u003c\/strong\u003e is very close to the thickness of many other popular filter brands. While perfect parfocality is never guaranteed across different manufacturers, this thickness should result in minimal focus shift when used in a filter wheel alongside other modern narrowband or LRGB filters. You may need only a very small focus adjustment.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does the ≥OD5 blocking on the SV227 OIII filter mean for my images?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003e\u003cstrong\u003eOD5 blocking\u003c\/strong\u003e means the filter blocks out-of-band light by a factor of 100,000 (Optical Density 5). This is a high level of blocking that ensures light from streetlights, the moon, and unwanted wavelengths from stars does not leak through and cause halos or gradients in your final image. It's a critical specification for clean, high-contrast astrophotography.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the SVBONY SV227 OIII filter for visual observing?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile technically possible on very bright planetary nebulae like the Ring Nebula (M57) with a large aperture telescope, it's generally not recommended. The \u003cstrong\u003e5nm bandpass\u003c\/strong\u003e is so restrictive that it makes the view extremely dim, and most stars will disappear entirely. This filter is designed specifically for long-exposure astrophotography, not visual use.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy is the 44mm clear aperture of the SV227 important?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e44mm clear aperture\u003c\/strong\u003e is larger than the diagonal of an APS-C sensor and nearly matches the diagonal of a full-frame sensor. This ensures that even with a fast optical system, the filter housing itself will not block light at the corners of your sensor, preventing vignetting and ensuring even illumination across your entire field of view.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes the M48x0.75 single thread on the SV227 filter cause any issues?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, this is standard. The \u003cstrong\u003eM48x0.75 single thread\u003c\/strong\u003e is on the side of the filter that threads into your camera or filter wheel. The other side is unthreaded. This design prevents you from accidentally stacking filters, which can cause internal reflections and degrade image quality. It ensures the filter is always mounted correctly in the optical train.\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\u003eOIII Narrowband\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize\u003c\/td\u003e\n\u003ctd\u003e2-Inch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCenter Wavelength (CWL)\u003c\/td\u003e\n\u003ctd\u003e500.7nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\n\u003ctd\u003e5nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePeak Transmittance\u003c\/td\u003e\n\u003ctd\u003e≥90%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBlocking Range\u003c\/td\u003e\n\u003ctd\u003e300-1000nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBlocking Depth\u003c\/td\u003e\n\u003ctd\u003e≥OD5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSubstrate Thickness\u003c\/td\u003e\n\u003ctd\u003e1.85mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eClear Aperture\u003c\/td\u003e\n\u003ctd\u003e44mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSurface Quality\u003c\/td\u003e\n\u003ctd\u003e60\/40\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSurface Parallelism\u003c\/td\u003e\n\u003ctd\u003e1\/4λ\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eParallelism (Angle)\u003c\/td\u003e\n\u003ctd\u003e30\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThread\u003c\/td\u003e\n\u003ctd\u003eM48x0.75\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThreading\u003c\/td\u003e\n\u003ctd\u003eSingle-Sided\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet Weight\u003c\/td\u003e\n\u003ctd\u003e12.5g \/ 0.44oz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/svbony-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eSVBONY Warranty Policy\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"SVBONY","offers":[{"title":"Default Title","offer_id":52861237166365,"sku":"SV-W9187DC","price":93.33,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/SVBONY-SV227-OIII-5nm-2-inch-Telescope-Filter-for-Nebula-Imaging-1_244e2422-e55d-42dd-bedc-ce93fe8bab7c.jpg?v=1788883686","url":"https:\/\/davidastro.com\/en-us\/products\/svbony-sv227-oiii-5nm-narrowband-filter-2in","provider":"David Astro","version":"1.0","type":"link"}