{"product_id":"svbony-sv220-7nm-sii-oiii-dual-band-filter-1-25-or-2","title":"SVBONY SV220 7nm SII \u0026 OIII Dual-Band Filter – 1.25″ or 2″","description":"\u003cstyle\u003e\n.dcs-sv220-sii{max-width:940px;margin:0 auto;color:#28394e;font-size:16px;line-height:1.7;overflow-wrap:break-word}\n.dcs-sv220-sii *{box-sizing:border-box}\n.dcs-sv220-sii p{font-size:16px;line-height:1.7;margin:0 0 16px}\n.dcs-sv220-sii h2{color:#10243d;font-size:27px;line-height:1.25;letter-spacing:-.3px;margin:0 0 16px;text-transform:none}\n.dcs-sv220-sii h3{color:#10243d;font-size:19px;line-height:1.4;margin:0 0 10px;text-transform:none}\n.dcs-sv220-sii a{color:#1c5579;text-underline-offset:3px}\n.dcs-sv220-sii a:focus-visible,.dcs-sv220-sii summary:focus-visible{outline:3px solid #ce941f;outline-offset:4px}\n.dcs-sv220-sii .dcs-hero{background:#10243d;color:#fff;border-top:5px solid #e8b641;border-radius:14px;padding:28px;margin:0 0 18px}\n.dcs-sv220-sii 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.dcs-benefits{padding:0;margin:22px 0;list-style:none}\n.dcs-sv220-sii .dcs-benefits li{padding:12px 12px 12px 16px;margin:0;border-bottom:1px solid #e2e8ef;border-left:3px solid #dfb457;font-size:15px;line-height:1.65}\n.dcs-sv220-sii .dcs-benefits li+li{margin-top:10px}\n.dcs-sv220-sii .dcs-benefits strong{color:#10243d}\n.dcs-sv220-sii .dcs-table-wrap{max-width:100%;overflow-x:auto;border:1px solid #dbe3eb;border-radius:10px;margin:20px 0}\n.dcs-sv220-sii table{width:100%;border:0;border-collapse:collapse;margin:0;background:#fff;font-size:14px;line-height:1.55}\n.dcs-sv220-sii th,.dcs-sv220-sii td{padding:12px;text-align:left;vertical-align:top;border:0;border-bottom:1px solid #e0e7ed;white-space:normal;overflow-wrap:break-word}\n.dcs-sv220-sii thead th{background:#10243d;color:#fff;font-weight:600}\n.dcs-sv220-sii tbody th{color:#233c56;font-weight:600;width:37%}\n.dcs-sv220-sii tbody tr:nth-child(even){background:#f3f6f9}\n.dcs-sv220-sii tr:last-child\u003e*{border-bottom:0}\n.dcs-sv220-sii .dcs-compare{min-width:420px}\n.dcs-sv220-sii .dcs-compare tbody th{width:30%}\n.dcs-sv220-sii .dcs-small{font-size:13px;line-height:1.6;color:#52647a}\n.dcs-sv220-sii .dcs-steps{padding-left:24px;margin:18px 0}\n.dcs-sv220-sii .dcs-steps li{padding-left:4px;margin:0 0 14px;font-size:15px;line-height:1.7}\n.dcs-sv220-sii details{border-bottom:1px solid #dce4ec;padding:0;background:none}\n.dcs-sv220-sii summary{display:list-item;cursor:pointer;padding:16px 4px;font-size:16px;font-weight:600;line-height:1.5;color:#163550}\n.dcs-sv220-sii details p{font-size:15px;padding:0 4px 6px}\n.dcs-sv220-sii .dcs-cta{background:#10243d;color:#e7eef5;padding:27px;border-radius:12px;margin-top:35px}\n.dcs-sv220-sii .dcs-cta h2{color:#fff;font-size:25px}\n.dcs-sv220-sii .dcs-button{display:inline-block;background:#efc45f;color:#10243d!important;border-radius:7px;padding:12px 18px;text-decoration:none;font-weight:700;margin:4px 0 17px;font-size:14px}\n.dcs-sv220-sii .dcs-related{font-size:14px;line-height:1.8;margin:0}\n.dcs-sv220-sii .dcs-cta .dcs-related a{color:#fff}\n.dcs-sv220-sii .dcs-brandline{font-size:12px;color:#e8c46c;margin-top:17px;padding-top:17px;border-top:1px solid #34516c}\n@media(max-width:600px){\n .dcs-sv220-sii p{font-size:15px}\n .dcs-sv220-sii h2{font-size:24px}\n .dcs-sv220-sii .dcs-hero,.dcs-sv220-sii .dcs-cta{padding:23px 20px}\n .dcs-sv220-sii .dcs-stats{grid-template-columns:repeat(2,minmax(0,1fr))}\n .dcs-sv220-sii .dcs-two{gap:20px}\n .dcs-sv220-sii .dcs-two\u003e*{flex-basis:100%}\n .dcs-sv220-sii th,.dcs-sv220-sii td{padding:10px;font-size:13px}\n}\n\u003c\/style\u003e\n\u003cdiv class=\"dcs-sv220-sii\"\u003e\n\u003csection class=\"dcs-hero\"\u003e\n  \u003cp class=\"dcs-eyebrow\"\u003eDark Clear Skies · SVBONY SV220 · W9172C \/ W9172D\u003c\/p\u003e\n  \u003ch2\u003eSV220 7nm SII \u0026amp; OIII\u003c\/h2\u003e\n  \u003cp class=\"dcs-subtitle\"\u003eAdd sulphur to your colour-camera nebula imaging.\u003c\/p\u003e\n  \u003cp\u003eRecord sulphur-II and oxygen-III emission together, then combine your data with a separate H-alpha\/OIII imaging session to build a three-channel SHO image. Choose the 1.25-inch or 2-inch mounted filter to suit your imaging train.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003cdiv class=\"dcs-stats\" aria-label=\"Key filter specifications\"\u003e\n  \u003cdiv class=\"dcs-stat\"\u003e\n\u003cstrong\u003eSII + OIII\u003c\/strong\u003e\u003cspan\u003eTwo nebula emission bands\u003c\/span\u003e\n\u003c\/div\u003e\n  \u003cdiv class=\"dcs-stat\"\u003e\n\u003cstrong\u003e7nm\u003c\/strong\u003e\u003cspan\u003eBandwidth per passband\u003c\/span\u003e\n\u003c\/div\u003e\n  \u003cdiv class=\"dcs-stat\"\u003e\n\u003cstrong\u003e≥88%\u003c\/strong\u003e\u003cspan\u003eSpecified peak transmission\u003c\/span\u003e\n\u003c\/div\u003e\n  \u003cdiv class=\"dcs-stat\"\u003e\n\u003cstrong\u003e1.25″ \/ 2″\u003c\/strong\u003e\u003cspan\u003eTwo mounted sizes\u003c\/span\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cp\u003eThe \u003cstrong\u003eSVBONY SV220 SII\/OIII dual-band filter\u003c\/strong\u003e is designed for emission-line astrophotography with a one-shot-colour camera. Its two narrow transmission windows select blue-green OIII around \u003cstrong\u003e500.7nm\u003c\/strong\u003e and deep-red SII around \u003cstrong\u003e672nm\u003c\/strong\u003e, while suppressing much of the light outside those bands.\u003c\/p\u003e\n\u003cp\u003eIt is particularly useful if you already image through an H-alpha\/OIII filter and want to capture a separate sulphur signal. That extra dataset gives you more control over nebula colour and the option to process your images in the SHO, or Hubble, palette.\u003c\/p\u003e\n\u003cfigure class=\"dcs-product-photo\"\u003e\n  \u003cdiv class=\"dcs-photo\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0523\/1650\/4241\/files\/W9172D_20260209091503_7866.webp?v=1794231860\" aria-label=\"Open larger image of the SV220 2-inch SII and OIII filter\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0523\/1650\/4241\/files\/W9172D_20260209091503_7866.webp?v=1794231860\" alt=\"SVBONY SV220 W9172D 2-inch filter with Duo-Band SII plus OIII 7nm lettering on the mounted cell\" width=\"1600\" height=\"1600\" loading=\"lazy\" decoding=\"async\"\u003e\u003c\/a\u003e\u003c\/div\u003e\n  \u003cfigcaption\u003eThe 2-inch W9172D shown here uses an M48 × 0.75 mounting thread. Select the correct size for your filter holder before ordering. Manufacturer image.\u003c\/figcaption\u003e\n\u003c\/figure\u003e\n\u003cul class=\"dcs-benefits\"\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCapture the sulphur your H-alpha\/OIII filter leaves out.\u003c\/strong\u003e Acquire a dedicated SII-containing exposure set without changing to a monochrome camera.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCollect oxygen at the same time.\u003c\/strong\u003e Both SII and OIII pass through the filter during each exposure, making useful use of the colour sensor's red and blue\/green response.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSuppress unwanted background light.\u003c\/strong\u003e The 7nm passbands and manufacturer-specified ≥OD5 out-of-band blocking help separate emission-line detail from surrounding sky glow.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMatch the fitting to your equipment.\u003c\/strong\u003e Choose the 26mm clear aperture of W9172C or the larger 44mm opening of W9172D.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003csection class=\"dcs-section\"\u003e\n  \u003ch2 class=\"dcs-section-heading\"\u003eFrom two filters to an SHO image\u003c\/h2\u003e\n  \u003cp\u003eSHO colour assigns \u003cstrong\u003eSII to red, H-alpha to green and OIII to blue\u003c\/strong\u003e. The SII\/OIII filter provides the sulphur and oxygen information; a separate H-alpha\/OIII filter supplies the hydrogen information in another exposure set.\u003c\/p\u003e\n  \u003cdiv class=\"dcs-table-wrap\"\u003e\u003ctable\u003e\n    \u003cthead\u003e\u003ctr\u003e\n\u003cth scope=\"col\"\u003eCapture stage\u003c\/th\u003e\n\u003cth scope=\"col\"\u003eFilter and useful data\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003e1 · Hydrogen and oxygen\u003c\/th\u003e\n\u003ctd\u003eCapture your target through an H-alpha\/OIII filter, such as the \u003ca href=\"https:\/\/www.darkclearskies.co.uk\/products\/sv220-telescope-filter-7nm-dual-band-nebula-2\"\u003eSV220 7nm H-alpha\/OIII\u003c\/a\u003e.\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003e2 · Sulphur and oxygen\u003c\/th\u003e\n\u003ctd\u003eReplace it with this SV220 SII\/OIII filter and capture another exposure set with matching framing.\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003e3 · Process and combine\u003c\/th\u003e\n\u003ctd\u003eCalibrate and align the datasets, extract the appropriate channel information and combine SII, H-alpha and OIII into the chosen colour palette.\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\u003c\/div\u003e\n  \u003cdiv class=\"dcs-note dcs-note-gold\"\u003e\n    \u003ch3\u003eUse the filters one at a time\u003c\/h3\u003e\n    \u003cp\u003eTake \u003cstrong\u003eseparate exposure sets\u003c\/strong\u003e through the two filters. Physically stacking an H-alpha\/OIII filter with an SII\/OIII filter does not create a three-band filter: each would reject wavelengths the other is intended to pass. A complete SHO image also needs suitable processing; it is not produced automatically by one exposure.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cp\u003eSulphur strength varies between targets and can be faint. Plan the integration time around the quality of each dataset rather than assuming every channel needs the same exposure time. Refocus and take suitable flat frames after changing filters.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003csection class=\"dcs-section\"\u003e\n  \u003ch2 class=\"dcs-section-heading\"\u003eWhat the 7nm passbands do\u003c\/h2\u003e\n  \u003cp\u003eFWHM, or full width at half maximum, describes a transmission band's width at half its peak. Each of this filter's two bands has a nominal \u003cstrong\u003e7nm FWHM\u003c\/strong\u003e. The filter selects useful emission wavelengths instead of passing the whole visible spectrum.\u003c\/p\u003e\n  \u003cfigure\u003e\n    \u003cdiv class=\"dcs-photo\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0523\/1650\/4241\/files\/w9172d-2_20251105182411_9478.webp?v=1794231860\" aria-label=\"Open the manufacturer's SV220 SII and OIII transmission graph\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0523\/1650\/4241\/files\/w9172d-2_20251105182411_9478.webp?v=1794231860\" alt=\"SVBONY transmission graph for the 2-inch SV220 7nm SII and OIII filter showing peaks near 500.7nm and 672nm\" width=\"1600\" height=\"1600\" loading=\"lazy\" decoding=\"async\"\u003e\u003c\/a\u003e\u003c\/div\u003e\n    \u003cfigcaption\u003eSVBONY's transmission illustration for W9172D shows the two narrow windows within the specified 300–1000nm wavelength range. It is a manufacturer reference graph, not an individual test certificate. Select the image for a larger view.\u003c\/figcaption\u003e\n  \u003c\/figure\u003e\n  \u003cp\u003eThe specified \u003cstrong\u003e≥88% peak transmission\u003c\/strong\u003e concerns the useful passbands. The \u003cstrong\u003e≥OD5 blocking\u003c\/strong\u003e concerns wavelengths outside those windows. The filter improves contrast by rejecting unwanted light; it does not increase the amount of nebula light reaching the telescope.\u003c\/p\u003e\n  \u003cdiv class=\"dcs-note\"\u003e\n\u003ch3\u003eLight pollution and moonlight still affect the result\u003c\/h3\u003e\n\u003cp\u003eLight within the transmitted bands can still reach the sensor. A narrowband filter can make emission-nebula imaging more productive under bright skies, while a darker sky, careful target choice and sufficient integration time remain valuable.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"dcs-section\"\u003e\n  \u003ch2 class=\"dcs-section-heading\"\u003eChoose the size for your complete imaging train\u003c\/h2\u003e\n  \u003cp\u003eThe two sizes transmit the same emission bands, but their mechanical fittings and clear openings differ. Match the \u003cstrong\u003efilter thread and cell clearance\u003c\/strong\u003e to your drawer, wheel or holder, then check the opening required by your sensor and light cone.\u003c\/p\u003e\n  \u003cdiv class=\"dcs-two\"\u003e\n    \u003cdiv class=\"dcs-card\"\u003e\n\u003ch3\u003e1.25-inch · W9172C\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eM28.5 × 0.6 thread · 26mm clear aperture.\u003c\/strong\u003e Choose it for a compatible 1.25-inch mounted-filter holder where the clear opening suits your camera and filter-to-sensor distance.\u003c\/p\u003e\n\u003c\/div\u003e\n    \u003cdiv class=\"dcs-card\"\u003e\n\u003ch3\u003e2-inch · W9172D\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eM48 × 0.75 thread · 44mm clear aperture.\u003c\/strong\u003e Choose it for a compatible 2-inch mounted-filter holder when the imaging train needs the larger opening.\u003c\/p\u003e\n\u003cp\u003eSVBONY’s W9172D drawing specifies a \u003cstrong\u003e50.8mm cell diameter and 7mm overall height\u003c\/strong\u003e. Check the holder’s clearance as well as its M48 × 0.75 mounting thread before ordering.\u003c\/p\u003e\n\u003c\/div\u003e\n  \u003c\/div\u003e\n\u003cdiv class=\"dcs-two\" style=\"margin-top:22px\"\u003e\n  \u003cfigure class=\"dcs-side-photo\"\u003e\n    \u003cdiv class=\"dcs-photo\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0523\/1650\/4241\/files\/w9172c-1_20251105180853_4357.webp?v=1794231860\" aria-label=\"Open larger image of the 1.25-inch W9172C filter\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0523\/1650\/4241\/files\/w9172c-1_20251105180853_4357.webp?v=1794231860\" alt=\"SVBONY SV220 W9172C 1.25-inch 7nm SII and OIII mounted filter\" width=\"1600\" height=\"1600\" loading=\"lazy\" decoding=\"async\"\u003e\u003c\/a\u003e\u003c\/div\u003e\n    \u003cfigcaption\u003eThe smaller W9172C has its own 1.25-inch fitting. It is a size choice on this listing, with a separate SKU from the 2-inch W9172D. Manufacturer image.\u003c\/figcaption\u003e\n  \u003c\/figure\u003e\n\u003cfigure class=\"dcs-side-photo\"\u003e\n\u003cdiv class=\"dcs-photo\"\u003e\u003ca href=\"https:\/\/res.svbony.com\/s_file\/20251105\/w9172d-8_20251105182413_5328.webp\" aria-label=\"Open the W9172D 2-inch filter dimensions\"\u003e\u003cimg src=\"https:\/\/res.svbony.com\/s_file\/20251105\/w9172d-8_20251105182413_5328.webp\" alt=\"SVBONY W9172D 2-inch SII and OIII filter drawing showing a 50.8mm cell diameter, 7mm overall height, M48 by 0.75 thread and 44mm clear aperture\" width=\"1600\" height=\"1600\" loading=\"lazy\" decoding=\"async\"\u003e\u003c\/a\u003e\u003c\/div\u003e\n\u003cfigcaption\u003eW9172D dimensions and clear aperture, shown in SVBONY’s manufacturer drawing. Full-frame coverage depends on the complete imaging train; the filter size alone does not guarantee it.\u003c\/figcaption\u003e\n\u003c\/figure\u003e\n\u003c\/div\u003e\n  \u003cp style=\"margin-top:20px\"\u003eA 2-inch filter does not guarantee unvignetted full-frame coverage. Sensor dimensions, the distance from filter to sensor, focal ratio and other restrictions in the light path all matter. A camera's M42 or M48 connection is also distinct from the filter mounting thread inside its holder.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003csection class=\"dcs-section\"\u003e\n  \u003ch2 class=\"dcs-section-heading\"\u003eCamera, telescope and target suitability\u003c\/h2\u003e\n  \u003cp\u003e\u003cstrong\u003eOne-shot-colour astronomy cameras:\u003c\/strong\u003e this is the intended application. The camera records both transmitted bands at once, and appropriate colour-channel processing is needed to make use of the sulphur and oxygen information.\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eMonochrome cameras:\u003c\/strong\u003e one exposure records the combined light from both bands as a greyscale image. Use separate single-band filters if you need independently isolated SII and OIII datasets on a mono sensor.\u003c\/p\u003e\n  \u003cp\u003e\u003cstrong\u003eDSLR and mirrorless cameras:\u003c\/strong\u003e check both the mounting arrangement and the camera's sensitivity around the deep-red SII band. An internal camera filter may attenuate that signal.\u003c\/p\u003e\n  \u003cdiv class=\"dcs-note dcs-note-gold\"\u003e\n\u003ch3\u003eFast optics need an individual check\u003c\/h3\u003e\n\u003cp\u003eInterference-filter passbands can shift as the incoming light angle changes. Tell us the telescope, reducer and working focal ratio before ordering for a very fast system. Physical fit alone does not establish optical suitability, and this filter should not be assumed compatible with an f\/2 RASA or HyperStar setup.\u003c\/p\u003e\n\u003c\/div\u003e\n  \u003cdiv class=\"dcs-two\"\u003e\n    \u003cdiv class=\"dcs-card\"\u003e\n\u003ch3\u003eEmission-line subjects\u003c\/h3\u003e\n\u003cp\u003eUse it for emission nebulae, planetary nebulae and supernova remnants with useful SII and\/or OIII emission. The relative strength of those signals varies across objects and structures.\u003c\/p\u003e\n\u003c\/div\u003e\n    \u003cdiv class=\"dcs-card\"\u003e\n\u003ch3\u003eBroadband subjects\u003c\/h3\u003e\n\u003cp\u003eGalaxies, reflection nebulae and star clusters emit much of their light outside these narrow windows. Use a suitable broadband approach when the aim is to capture their continuum light and natural star colours.\u003c\/p\u003e\n\u003c\/div\u003e\n  \u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"dcs-section\"\u003e\n  \u003ch2 class=\"dcs-section-heading\"\u003eTechnical specifications\u003c\/h2\u003e\n  \u003cdiv class=\"dcs-table-wrap\"\u003e\u003ctable class=\"dcs-compare\"\u003e\n    \u003cthead\u003e\u003ctr\u003e\n\u003cth scope=\"col\"\u003eSpecification\u003c\/th\u003e\n\u003cth scope=\"col\"\u003e1.25-inch · W9172C\u003c\/th\u003e\n\u003cth scope=\"col\"\u003e2-inch · W9172D\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003eManufacturer \/ model\u003c\/th\u003e\n\u003ctd\u003eSVBONY \/ SV220\u003c\/td\u003e\n\u003ctd\u003eSVBONY \/ SV220\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003eFilter type\u003c\/th\u003e\n\u003ctd\u003eSII\/OIII dual-band imaging filter\u003c\/td\u003e\n\u003ctd\u003eSII\/OIII dual-band imaging filter\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003eNominal band centres\u003c\/th\u003e\n\u003ctd\u003eOIII 500.7nm; SII approximately 672nm\u003c\/td\u003e\n\u003ctd\u003eOIII 500.7nm; SII approximately 672nm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003eFWHM per passband\u003c\/th\u003e\n\u003ctd\u003e7nm\u003c\/td\u003e\n\u003ctd\u003e7nm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003ePeak transmission\u003c\/th\u003e\n\u003ctd\u003e≥88%\u003c\/td\u003e\n\u003ctd\u003e≥88%\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003eSpecified wavelength range\u003c\/th\u003e\n\u003ctd\u003e300–1000nm\u003c\/td\u003e\n\u003ctd\u003e300–1000nm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003eOut-of-band blocking\u003c\/th\u003e\n\u003ctd\u003e≥OD5\u003c\/td\u003e\n\u003ctd\u003e≥OD5\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003eClear aperture\u003c\/th\u003e\n\u003ctd\u003e26mm\u003c\/td\u003e\n\u003ctd\u003e44mm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003eMounting thread\u003c\/th\u003e\n\u003ctd\u003eM28.5 × 0.6; single thread\u003c\/td\u003e\n\u003ctd\u003eM48 × 0.75; single thread\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003eSubstrate thickness\u003c\/th\u003e\n\u003ctd\u003e1.80mm\u003c\/td\u003e\n\u003ctd\u003e1.85mm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003eSurface quality\u003c\/th\u003e\n\u003ctd\u003e60\/40\u003c\/td\u003e\n\u003ctd\u003e60\/40\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003cth scope=\"row\"\u003eManufacturer-listed net weight\u003c\/th\u003e\n\u003ctd\u003e7g\u003c\/td\u003e\n\u003ctd\u003e15–20g\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\u003c\/div\u003e\n  \u003cp class=\"dcs-small\"\u003eFigures are manufacturer specifications. Substrate thickness is the glass thickness, not the total cell height or the spacing added by a complete filter holder. The wavelength range is not a continuous passband: light is intended to pass through the two narrow windows.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003csection class=\"dcs-section\"\u003e\n  \u003ch2 class=\"dcs-section-heading\"\u003eWhat you are ordering\u003c\/h2\u003e\n  \u003cp\u003e\u003cstrong\u003eOne mounted SVBONY SV220 7nm SII\/OIII filter in the selected size:\u003c\/strong\u003e W9172C for 1.25-inch or W9172D for 2-inch.\u003c\/p\u003e\n  \u003cp\u003eA separate H-alpha\/OIII filter, camera, telescope, filter holder and any adapters are additional items. The size choices on this page are individual filters, not a two-filter SHO set.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003csection class=\"dcs-section\"\u003e\n  \u003ch2 class=\"dcs-section-heading\"\u003eQuestions before you buy\u003c\/h2\u003e\n  \u003cdetails\u003e\u003csummary\u003eIs this the same as the SV220 H-alpha\/OIII filter?\u003c\/summary\u003e\u003cp\u003eIt records different red-band information. W9172C and W9172D transmit SII and OIII. W9172A and W9172B are the 7nm H-alpha\/OIII versions; W9198A and W9198B are the 3nm H-alpha\/OIII versions. Check the SKU, bands and diameter together.\u003c\/p\u003e\u003c\/details\u003e\n  \u003cdetails\u003e\u003csummary\u003eCan I create an SHO image with this filter alone?\u003c\/summary\u003e\u003cp\u003eThis filter records sulphur and oxygen. Full SHO also requires separately acquired H-alpha information and processing to combine the channels. A separate H-alpha\/OIII filter is a practical companion for a colour-camera workflow.\u003c\/p\u003e\u003c\/details\u003e\n  \u003cdetails\u003e\u003csummary\u003eCan I use it with an existing 3nm H-alpha\/OIII filter?\u003c\/summary\u003e\u003cp\u003eThe two filters can collect complementary datasets in separate exposure sets, provided each is suitable for the optical system. Their bandwidths, backgrounds and transmission differ, so process and balance the datasets individually instead of assuming identical signal levels.\u003c\/p\u003e\u003c\/details\u003e\n  \u003cdetails\u003e\u003csummary\u003eWill I need to refocus?\u003c\/summary\u003e\u003cp\u003eCheck focus after changing filters. Glass thickness and the rest of the optical train affect the focus position. Follow the telescope or corrector manufacturer's spacing guidance and capture calibration frames appropriate to each filter arrangement.\u003c\/p\u003e\u003c\/details\u003e\n  \u003cdetails\u003e\u003csummary\u003eDoes the filter guarantee halo-free stars?\u003c\/summary\u003e\u003cp\u003eNo. Reflections and halos depend on the filter, camera window, bright stars and other optical surfaces. Check your own imaging train rather than assuming any filter will eliminate every reflection.\u003c\/p\u003e\u003c\/details\u003e\n\u003c\/section\u003e\n\u003csection class=\"dcs-cta\"\u003e\n  \u003ch2\u003eBuild the right filter pairing for your camera\u003c\/h2\u003e\n  \u003cp\u003eTell us your telescope, reducer, camera and filter holder. Dark Clear Skies can help you choose the diameter and check how this SII\/OIII filter fits into your imaging workflow.\u003c\/p\u003e\n  \u003ca class=\"dcs-button\" href=\"https:\/\/www.darkclearskies.co.uk\/pages\/contact\"\u003eAsk DCS about your setup\u003c\/a\u003e\n  \u003cp class=\"dcs-related\"\u003e\u003ca href=\"https:\/\/www.darkclearskies.co.uk\/products\/sv220-telescope-filter-7nm-dual-band-nebula-2\"\u003eSV220 7nm H-alpha\/OIII · both sizes\u003c\/a\u003e\u003cbr\u003e\u003ca href=\"https:\/\/www.darkclearskies.co.uk\/products\/svbony-sv220-1-25-3nm-h-alpha-oiii-dual-band-filter-w9198a\"\u003eSV220 3nm H-alpha\/OIII · 1.25-inch\u003c\/a\u003e · \u003ca href=\"https:\/\/www.darkclearskies.co.uk\/products\/svbony-sv220-2-inch-3nm-narrowband-filter\"\u003eSV220 3nm H-alpha\/OIII · 2-inch\u003c\/a\u003e\u003cbr\u003e\u003ca href=\"https:\/\/www.darkclearskies.co.uk\/collections\/svbony-telescope-filters\"\u003eExplore SVBONY telescope filters\u003c\/a\u003e\u003c\/p\u003e\n  \u003cdiv class=\"dcs-brandline\"\u003eDark Clear Skies · Passion for the Night Sky, Delivered.\u003c\/div\u003e\n\u003c\/section\u003e\n\u003c\/div\u003e\n","brand":"SVBONY","offers":[{"title":"2\"","offer_id":55731083149688,"sku":"W9172D","price":149.99,"currency_code":"GBP","in_stock":false},{"title":"1.25\"","offer_id":55731083182456,"sku":"W9172C","price":119.99,"currency_code":"GBP","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0523\/1650\/4241\/files\/W9172D_20260209091503_7866.webp?v=1794231860","url":"https:\/\/www.darkclearskies.co.uk\/products\/svbony-sv220-7nm-sii-oiii-dual-band-filter-1-25-or-2","provider":"Dark Clear Skies ","version":"1.0","type":"link"}