{"title":"William Optics Flatteners \u0026 Reducers","description":"\u003cp\u003eWilliam Optics Flatteners \u0026amp; Reducers. Part of \u003ca href=\"\/collections\/flatteners-and-reducers\"\u003eFlatteners, Reducers \u0026amp; Correctors\u003c\/a\u003e.\u003c\/p\u003e","products":[{"product_id":"william-optics-flat73r-reducer-flattener-with-rotator","title":"William Optics Flat73R Reducer Flattener with Rotator","description":"\u003cspan style=\"font-family: Arial;\"\u003eIncrease your filed of view on the Zenith Star 73 with the William Optics 0.8x Reducer with built in rotator.  \u003c\/span\u003e\u003cdiv\u003e\u003cspan style=\"font-family: Arial;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"font-family: Arial;\"\u003eThe adjustment ring allows for precise adjustment to get the correct spacing.  For DSLR's adjust the space ring to 1.8mm to get the required 55mm of back space when using a standard T-Ring.\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"font-family: Arial;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\n\u003cp style=\"margin: 0px 0px 1rem; padding: 0px; color: rgb(51, 51, 51); font-family: \" open sans arial neue helvetica sans-serif font-size: background-color: rgb\u003e\u003cimg src=\"https:\/\/williamoptics.com\/pub\/media\/wysiwyg\/Product\/P-FLAT73R\/Flat%2073%20R%203.jpg\" alt=\"\" style=\"margin: 0px; padding: 0px; border: 0px; height: auto; max-width: 100%; vertical-align: top;\"\u003e\u003c\/p\u003e\n\u003cp style=\"margin: 0px 0px 1rem; padding: 0px; color: rgb(51, 51, 51); font-family: \" open sans arial neue helvetica sans-serif font-size: background-color: rgb\u003e\u003cimg src=\"https:\/\/williamoptics.com\/pub\/media\/wysiwyg\/Product\/P-FLAT73R\/Flat%2073%20R%204.jpg\" alt=\"\" style=\"margin: 0px; padding: 0px; border: 0px; height: auto; max-width: 100%; vertical-align: top;\"\u003e\u003c\/p\u003e\n\u003cp style=\"margin: 0px 0px 1rem; padding: 0px; color: rgb(51, 51, 51); font-family: \" open sans arial neue helvetica sans-serif font-size: background-color: rgb\u003e\u003cimg src=\"https:\/\/williamoptics.com\/pub\/media\/wysiwyg\/Product\/P-FLAT73R\/Flat%2073%20R%205.jpg\" alt=\"\" style=\"margin: 0px; padding: 0px; border: 0px; height: auto; max-width: 100%; vertical-align: top;\"\u003e\u003c\/p\u003e\n\u003cp style=\"margin: 0px 0px 1rem; padding: 0px; color: rgb(51, 51, 51); font-family: \" open sans arial neue helvetica sans-serif font-size: background-color: rgb\u003e\u003cimg src=\"https:\/\/williamoptics.com\/media\/wysiwyg\/Product\/P-FLAT61R\/Flat%2061%20R%204%201.jpg\" alt=\"\" style=\"margin: 0px; padding: 0px; max-width: 100%; height: auto; border: 0px; vertical-align: top;\"\u003e\u003c\/p\u003e\n\u003c\/div\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44013579173999,"sku":"P-FLAT73R","price":369.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/img_5404__54471.png?v=1766556837"},{"product_id":"william-optics-flat6aiii-special-edition-for-fluorostar-91","title":"William Optics FLAT6AIII special edition for Fluorostar 91","description":"\u003cp style=\"box-sizing: border-box; -webkit-font-smoothing: subpixel-antialiased; margin: 1em 0px; line-height: 1.8; color: rgb(64, 64, 64); font-family: \" pt sans sans-serif justify rgb font-size:=\"\" text-align:=\"\" background-color:=\"\"\u003eAdjust the distance for DSLR and mirrorless camera with the William Optics FLAT6AIII.\u003c\/p\u003e\u003cp style=\"box-sizing: border-box; -webkit-font-smoothing: subpixel-antialiased; margin: 1em 0px; line-height: 1.8; color: rgb(64, 64, 64); font-family: \" pt sans sans-serif justify rgb font-size:=\"\" text-align:=\"\" background-color:=\"\"\u003eSpecifications\u003c\/p\u003e\u003cp style=\"box-sizing: border-box; -webkit-font-smoothing: subpixel-antialiased; margin: 1em 0px; line-height: 1.8; color: rgb(64, 64, 64); font-family: \" pt sans sans-serif justify rgb font-size:=\"\" text-align:=\"\" background-color:=\"\"\u003e\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eFull frame size\u003c\/li\u003e\n\u003cli\u003eDesigned with nearly Full frame chip-size DSLR cameras in mind\u003c\/li\u003e\n\u003cli\u003eFMC triplet APO design\u003c\/li\u003e\n\u003cli\u003eProduced entirely with the best Ohara optical glasses\u003c\/li\u003e\n\u003cli\u003eReducing factor 0.8X\u003c\/li\u003e\n\u003cli\u003eAdjustable design, for perfect back focus it can be used with other models of refractor\u003c\/li\u003e\n\u003cli\u003e48mm filter ready\u003c\/li\u003e\n\u003cli\u003eSuperb Finish\u003c\/li\u003e\n\u003cli\u003eWilliam Optics polished anodized finish\u003c\/li\u003e\n\u003cli\u003eAll internal surfaces threaded and blackened to prevent reflections\u003c\/li\u003e\n\u003cli\u003eEasy to Use\u003c\/li\u003e\n\u003cli\u003eWill accept any standard 48mm T-ring for your camera\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp style=\"box-sizing: border-box; -webkit-font-smoothing: subpixel-antialiased; margin: 1em 0px; line-height: 1.8; color: rgb(64, 64, 64); font-family: \" pt sans sans-serif justify rgb font-size:=\"\" text-align:=\"\" background-color:=\"\"\u003e\u003cbr style=\"box-sizing: border-box; -webkit-font-smoothing: subpixel-antialiased;\"\u003e\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44013645594735,"sku":"P-FLAT6AIII-M92","price":480.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/flat6aiii__35834.jpg?v=1766558494"},{"product_id":"william-optics-flat-61a-field-flattener","title":"William Optics FLAT 61A Field Flattener","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics FLAT 61A\u003c\/strong\u003e is a 1.0x field flattener designed to improve edge-to-edge star sharpness when imaging with compatible William Optics refractors, especially the Zenithstar 61. It helps correct field curvature so astrophotographers can capture cleaner stars across APS-C and full-frame camera sensors.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eThe FLAT 61A is best for astrophotographers using a Zenithstar 61 or compatible small William Optics refractor who want a flatter imaging field for deep-sky photography.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.0x correction:\u003c\/strong\u003e Flattens the field without reducing focal length.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAPS-C and full-frame support:\u003c\/strong\u003e Designed for common astronomy and DSLR\/mirrorless camera setups.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCamera adapter support:\u003c\/strong\u003e Uses an M48 camera-side thread and supports common T-mount ecosystems.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eWide-field deep-sky astrophotography\u003c\/li\u003e\n\u003cli\u003eImproving star shape at the edge of the frame\u003c\/li\u003e\n\u003cli\u003eZenithstar 61 imaging setups\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eUse the recommended back focus spacing for your telescope and camera. Customers should confirm camera adapter, T-ring, and spacing requirements before imaging.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is an imaging accessory, not a visual observing accessory. Correct spacing is required for best results.\u003c\/p\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003ch3\u003eDoes the FLAT 61A reduce focal length?\u003c\/h3\u003e\u003cp\u003eNo. It is a 1.0x field flattener.\u003c\/p\u003e\u003ch3\u003eWhich telescope is it mainly for?\u003c\/h3\u003e\u003cp\u003eIt is primarily intended for Zenithstar 61 imaging systems.\u003c\/p\u003e\u003ch2\u003eOur Recommendation\u003c\/h2\u003e\u003cp\u003eChoose the FLAT 61A if you image with a Zenithstar 61 and want cleaner corner stars without changing the telescope’s focal length.\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154238627951,"sku":"P-FLAT61A","price":384.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-flat-61a.jpg?v=1779654739"},{"product_id":"william-optics-flat-6aiii-0-8x-reducer-flattener","title":"William Optics FLAT 6AIII 0.8x Reducer Flattener","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics FLAT 6AIII\u003c\/strong\u003e is a 0.8x reducer flattener designed for astrophotographers who want a wider field of view, faster imaging speed, and improved edge-to-edge star correction with compatible William Optics refractors.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eBest for deep-sky astrophotographers using compatible William Optics refractors who want to reduce focal length while flattening the imaging field.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e0.8x reduction:\u003c\/strong\u003e Widens the field of view and speeds up imaging.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eField correction:\u003c\/strong\u003e Helps improve star shape from centre to edge.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImaging-focused design:\u003c\/strong\u003e Built for camera-based astrophotography setups.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eWide-field deep-sky astrophotography\u003c\/li\u003e\n\u003cli\u003eFaster imaging with compatible refractors\u003c\/li\u003e\n\u003cli\u003eImproving corner star quality\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eUse with compatible William Optics refractors and the correct adapter\/backfocus spacing for your camera system. Check camera adapter, T-ring, filter wheel, and spacing requirements before imaging.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is not a visual observing accessory. Correct spacing is required for best results.\u003c\/p\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003ch3\u003eDoes the FLAT 6AIII reduce focal length?\u003c\/h3\u003e\u003cp\u003eYes. It provides 0.8x reduction.\u003c\/p\u003e\u003ch3\u003eWhat problem does it solve?\u003c\/h3\u003e\u003cp\u003eIt helps flatten the field and improves edge star shape while widening the image field.\u003c\/p\u003e\u003ch2\u003eOur Recommendation\u003c\/h2\u003e\u003cp\u003eChoose the FLAT 6AIII if your compatible William Optics refractor needs a reducer\/flattener for faster wide-field deep-sky imaging.\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154238988399,"sku":"P-FLAT6AIII","price":371.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-flat-6aiii-reducer.jpg?v=1779654753"},{"product_id":"william-optics-flat-gt-field-flattener","title":"William Optics FLAT GT Field Flattener","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics FLAT GT\u003c\/strong\u003e is a 1.0x field flattener for compatible Gran Turismo refractors, designed to improve edge-to-edge star sharpness without reducing focal length.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eBest for astrophotographers using compatible William Optics GT refractors who want a flatter imaging field for deep-sky photography.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.0x correction:\u003c\/strong\u003e Keeps the telescope focal length unchanged.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eField flattening:\u003c\/strong\u003e Improves corner star shape.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGT compatibility:\u003c\/strong\u003e Designed for compatible Gran Turismo refractor setups.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eDeep-sky astrophotography\u003c\/li\u003e\n\u003cli\u003eGT refractor imaging setups\u003c\/li\u003e\n\u003cli\u003eImproving corner stars\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eConfirm telescope compatibility, camera adapter, and required backfocus spacing before imaging.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is an imaging accessory and requires correct spacing for best results.\u003c\/p\u003e\u003ch2\u003eOur Recommendation\u003c\/h2\u003e\u003cp\u003eChoose the FLAT GT when your compatible GT refractor needs field correction without focal reduction.\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154240954479,"sku":"P-FLAT-GT","price":361.2,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-flat-gt.jpg?v=1779654768"},{"product_id":"william-optics-flat-73a-field-flattener","title":"William Optics FLAT 73A Field Flattener","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics FLAT 73A\u003c\/strong\u003e is a 1.0x field flattener designed for compatible William Optics refractors, especially Zenithstar 73 imaging systems. It helps correct field curvature so astrophotographers can capture sharper stars from the centre to the edge of the frame.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eBest for astrophotographers using a compatible William Optics refractor who want improved corner star performance without reducing focal length.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.0x correction:\u003c\/strong\u003e Keeps the telescope focal length unchanged.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eField flattening:\u003c\/strong\u003e Helps improve edge-to-edge star shape.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImaging accessory:\u003c\/strong\u003e Designed for camera-based deep-sky astrophotography.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eZenithstar 73 astrophotography\u003c\/li\u003e\n\u003cli\u003eWide-field deep-sky imaging\u003c\/li\u003e\n\u003cli\u003eImproving corner star sharpness\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eConfirm telescope compatibility, adapter requirements, and camera backfocus spacing before imaging.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is an imaging accessory and requires correct spacing for best results.\u003c\/p\u003e\u003ch2\u003eOur Recommendation\u003c\/h2\u003e\u003cp\u003eChoose the FLAT 73A if your compatible William Optics refractor needs field correction without focal reduction.\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154242265199,"sku":"P-FLAT73A","price":384.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-flat-73a.jpg?v=1779654781"},{"product_id":"william-optics-flat-68iii-field-flattener","title":"William Optics FLAT 68III Field Flattener","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics FLAT 68III\u003c\/strong\u003e is a premium 1.0x field flattener for compatible William Optics refractors and full-frame astrophotography systems. It is designed to correct field curvature and improve star shape across large camera sensors without reducing focal length.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eBest for astrophotographers using compatible William Optics refractors who want full-frame field correction while keeping the telescope’s native focal length.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.0x correction:\u003c\/strong\u003e Maintains native focal length.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull-frame imaging support:\u003c\/strong\u003e Designed for larger camera sensors.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eField flattening:\u003c\/strong\u003e Helps improve edge-to-edge star quality.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eFull-frame deep-sky astrophotography\u003c\/li\u003e\n\u003cli\u003eCompatible William Optics refractor imaging\u003c\/li\u003e\n\u003cli\u003eImproving corner star shape\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eConfirm your telescope model, adapter requirements, camera thread, and backfocus spacing before imaging.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is an imaging accessory and correct spacing is required for best results.\u003c\/p\u003e\u003ch2\u003eOur Recommendation\u003c\/h2\u003e\u003cp\u003eChoose the FLAT 68III when you need premium full-frame field correction without focal reduction.\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154242658415,"sku":"P-FLAT68III","price":1087.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-flat-68iii.jpg?v=1779654796"},{"product_id":"william-optics-ultra-flat-132-0-79x-reducer","title":"William Optics Ultra Flat 132 0.79x Reducer","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics Ultra Flat 132\u003c\/strong\u003e is a 0.79x reducer-flattener built as the matched corrector for the William Optics Fluorostar 132. It is a three-element, three-group design with a 137.5 mm optical length, an M92 x 1 telescope-side thread, and an M54 x 0.75 camera-side thread. On the Fluorostar 132 it delivers a corrected image circle of 43.2 mm at 55 mm of backfocus, and it weighs 1096 g.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThis is a good match if you already own — or are ordering — a Fluorostar 132 and intend to image with it. It is the corrector that pairs with that telescope, so the decision is less about choosing between flatteners and more about whether you want the 0.79x reduced configuration rather than the native focal length.\u003c\/p\u003e\n\u003cp\u003eIt suits a deep-sky imaging rig running a full-frame or APS-C camera. Setting it up is refreshingly direct: the supplied PVC gasket sets the 55 mm spacing on the Fluorostar 132, so there is no adjustment ring to dial in and no trial-and-error before your first session.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e0.79x reduction:\u003c\/strong\u003e multiplies the native focal length and focal ratio of the Fluorostar 132 by 0.79. Because focal ratio scales linearly and light-gathering per unit area scales with its square, the reduced configuration collects roughly 1.6x more light per unit time (1 \/ 0.79²) than the native configuration.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e3 groups, 3 elements:\u003c\/strong\u003e a three-element corrector group, each element air-spaced as its own group.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e137.5 mm optical length:\u003c\/strong\u003e the corrector's own contribution to the imaging train, before your camera spacing. This is a long assembly — nearly twice the optical length of the Ultra Flat 156 — so account for it when planning the train.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eM92 x 1 x 6.5 mm telescope thread:\u003c\/strong\u003e threads directly to the Fluorostar 132 focuser drawtube — no push-fit, no adapter.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eM54 x 0.75 x 4 mm camera thread:\u003c\/strong\u003e the camera-side interface from which 55 mm of backfocus is measured.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e43.2 mm corrected image circle:\u003c\/strong\u003e on the Fluorostar 132, covering a full-frame sensor (43.3 mm diagonal).\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e1096 g:\u003c\/strong\u003e plan your focuser load and any rotator or filter wheel accordingly.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eA reducer-flattener does two jobs at once. Fast refractors of this aperture project a field that is curved rather than flat — stars that focus sharply at the centre fall progressively out of focus toward the edges, because the natural focal surface is a shallow bowl rather than a plane, and your sensor is a plane. The corrector group flattens that surface onto the sensor. The 0.79x element compresses the image scale at the same time, shortening the effective focal length and lowering the focal ratio, which shortens the exposure needed for a given signal.\u003c\/p\u003e\n\u003cp\u003eThe three-element, three-group construction is what allows both corrections to be made without reintroducing colour error at the edges. The consequence is that spacing tolerance drives corner star quality: the design is computed for one specific separation between the M54 thread and your sensor. Under-space it and corner stars elongate radially; over-space it and they elongate tangentially. The centre of the frame looks fine either way, which is why the corners are the place to check your work — and why the supplied gasket, which sets the spacing for you on the Fluorostar 132, is worth using as directed.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eDeep-sky astrophotography with a Fluorostar 132 in its reduced 0.79x configuration\u003c\/li\u003e\n  \u003cli\u003eFull-frame and APS-C cooled camera imaging where a flat field to the corners is required\u003c\/li\u003e\n  \u003cli\u003eWider framing than the Fluorostar 132 delivers natively — larger nebulae, extended galaxy fields\u003c\/li\u003e\n  \u003cli\u003eShorter sub-exposures at the same signal level, useful under mediocre guiding or shorter imaging windows\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eWilliam Optics publishes this corrector as the match for the \u003cstrong\u003eFluorostar 132\u003c\/strong\u003e. On the Fluorostar 132 it requires \u003cstrong\u003e55 mm of backfocus\u003c\/strong\u003e and needs \u003cstrong\u003eno adjustment\u003c\/strong\u003e — set the spacing with the supplied PVC gasket as directed. Backfocus is measured from the M54 x 0.75 camera-side thread to your sensor plane, and the total must account for every component in the train: filter drawer or filter wheel, off-axis guider, rotator, and the camera's own sensor-to-flange distance.\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/Flattener_back_focus-04.jpg?v=1784224665\" alt=\"William Optics flattener back focus diagram showing the 55 mm spacing measured from the M54 camera-side thread of the Ultra Flat 132\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\n\u003cp\u003eThe telescope side is \u003cstrong\u003eM92 x 1\u003c\/strong\u003e, threading straight to the Fluorostar 132. The camera side is \u003cstrong\u003eM54 x 0.75\u003c\/strong\u003e; most cooled astronomy cameras present an M48 or T2 interface, so confirm what your specific camera and filter hardware need to reach M54 and budget that adapter's optical length within the 55 mm figure — not on top of it. If you are not sure what your train adds up to, send us your camera and filter setup and we will work it out with you.\u003c\/p\u003e\n\u003cp\u003eWilliam Optics also publishes a back focus adjustment guide for the Ultra Flat series. If you are matching a different William Optics telescope, contact us before ordering — the Fluorostar 156 uses the \u003ca href=\"\/products\/william-optics-ultra-flat-156-0-79x-reducer\"\u003eUltra Flat 156\u003c\/a\u003e, and the Fluorostar 132 is also listed as compatible with the FLAT 68III, FLAT 7A, and FLAT 8 correctors at their own respective reduction factors.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eImaging accessory:\u003c\/strong\u003e this is an optical corrector for astrophotography. It has no application in a visual train with an eyepiece.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMatched to the Fluorostar 132:\u003c\/strong\u003e the 43.2 mm image circle and 55 mm backfocus are the figures William Optics publishes for that telescope. Other William Optics refractors pair with their own correctors — if you are matching a different model, get in touch and we will confirm the right one.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSpacing matters:\u003c\/strong\u003e corner star shape depends on hitting the 55 mm backfocus. On the Fluorostar 132 the supplied PVC gasket sets it, with no further adjustment needed.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCamera-side adapter:\u003c\/strong\u003e the corrector presents M54 x 0.75, while most cooled cameras and filter wheels use M48 or T2. An adapter is usually needed and is sold separately — its optical length counts toward the 55 mm, not on top of it. We can help you identify the right one for your camera.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSensor coverage:\u003c\/strong\u003e the 43.2 mm corrected circle on the Fluorostar 132 covers a full-frame sensor (43.3 mm diagonal). William Optics lists this corrector for APS-C and full frame.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOptical length:\u003c\/strong\u003e at 137.5 mm this is a long corrector — worth checking against your focuser travel and any dew shield or clearance constraints.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWhat telescope does this work with?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eWilliam Optics lists it as the matched corrector for the Fluorostar 132, with a 43.2 mm image circle at 55 mm backfocus and no adjustment required.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo. On the Fluorostar 132 it threads straight to the M92 drawtube and the supplied PVC gasket sets the 55 mm spacing for you — there is no adjustment ring to dial in and no trial-and-error. The main thing to get right is the total distance from the M54 thread to your sensor, and we are happy to check that with you before you order.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use it for visual observing?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo. It is a reducer-flattener for imaging. It has no place in a visual train.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat backfocus do I need?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e55 mm, measured from the M54 x 0.75 camera-side thread to your sensor plane. Use the supplied PVC gasket as directed; the Fluorostar 132 pairing requires no further adjustment.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill it cover a full-frame sensor?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes. The published corrected image circle on the Fluorostar 132 is 43.2 mm, and a full-frame sensor has a 43.3 mm diagonal — so the corrected field is sized to full frame. William Optics lists the camera format as APS-C and full frame.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the difference between this and the Ultra Flat 156?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eBoth are 0.79x correctors, but they are computed for different telescopes: the Ultra Flat 132 is matched to the Fluorostar 132 and the Ultra Flat 156 to the Fluorostar 156. They also differ mechanically — 137.5 mm optical length here versus 75.5 mm on the 156. They are not interchangeable.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need any additional adapters?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eVery likely on the camera side. The corrector presents M54 x 0.75; most cooled cameras and filter wheels use M48 or T2. Any adapter you add consumes part of the 55 mm backfocus budget. Tell us what camera you are running and we will point you to the right adapter.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes it change my focal length?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes — it multiplies the native focal length and focal ratio of the Fluorostar 132 by 0.79, which widens the field and shortens the exposure needed for a given signal.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: the matched 0.79x reducer-flattener for the Fluorostar 132. It threads on at M92, presents M54 to your camera, needs 55 mm of backfocus with the supplied gasket, and delivers a flat 43.2 mm field sized to a full-frame sensor. Spacing is the one figure worth measuring carefully — the corners are where it shows.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eOptical Diagram Reports\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eWilliam Optics publishes measured diagram reports for the Ultra Flat 132 on the Fluorostar 132. These show the corrected performance across the field rather than a marketing claim about it.\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FLT-132_Flat132-Diagram-1.jpg?v=1784224665\" alt=\"William Optics Ultra Flat 132 optical test diagram report for the Fluorostar 132 imaging system\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FLT-132_Flat132-Diagram-2.jpg?v=1784224665\" alt=\"William Optics Ultra Flat 132 spot diagram report showing corrected star images across the 43.2 mm image circle\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154243149935,"sku":"P-FLAT132","price":1474.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-ultra-flat-132.jpg?v=1779654809"},{"product_id":"william-optics-ultra-flat-156-0-79x-reducer","title":"William Optics Ultra Flat 156 0.79x Reducer","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics Ultra Flat 156\u003c\/strong\u003e is a 0.79x reducer-flattener built as the matched corrector for the William Optics Fluorostar 156. It is a three-element, three-group design with a 75.5 mm optical length, an M92 x 1 telescope-side thread, and an M54 x 0.75 camera-side thread. On the Fluorostar 156 it delivers a corrected image circle of 43.2 mm at 55 mm of backfocus, and it weighs 1202 g.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThis is a good match if you already own — or are ordering — a Fluorostar 156 and intend to image with it. It is the corrector that pairs with that telescope, so the decision is less about choosing between flatteners and more about whether you want the 0.79x reduced configuration rather than the native focal length.\u003c\/p\u003e\n\u003cp\u003eIt suits a permanent or semi-permanent deep-sky imaging rig running a full-frame or APS-C camera. At 1202 g on top of a 156 mm refractor, this is not a travel-weight combination. Setting it up is refreshingly direct: the supplied PVC gasket sets the 55 mm spacing on the Fluorostar 156, so there is no trial-and-error to work through before your first session.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e0.79x reduction:\u003c\/strong\u003e multiplies the native focal length and focal ratio of the Fluorostar 156 by 0.79. Because focal ratio scales linearly and light-gathering per unit area scales with its square, the reduced configuration collects roughly 1.6x more light per unit time (1 \/ 0.79²) than the native configuration.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e3 groups, 3 elements:\u003c\/strong\u003e a three-element corrector group, each element air-spaced as its own group.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e75.5 mm optical length:\u003c\/strong\u003e the corrector's own contribution to the imaging train, before your camera spacing.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eM92 x 1 x 6.5 mm telescope thread:\u003c\/strong\u003e threads directly to the Fluorostar 156 focuser drawtube — no push-fit, no adapter.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eM54 x 0.75 x 4 mm camera thread:\u003c\/strong\u003e the camera-side interface from which 55 mm of backfocus is measured.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e43.2 mm corrected image circle:\u003c\/strong\u003e on the Fluorostar 156, covering a full-frame sensor (43.3 mm diagonal).\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e1202 g:\u003c\/strong\u003e plan your focuser load and any rotator or filter wheel accordingly.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eA reducer-flattener does two jobs at once. Fast refractors of this aperture project a field that is curved rather than flat — stars that focus sharply at the centre fall progressively out of focus toward the edges, because the natural focal surface is a shallow bowl rather than a plane, and your sensor is a plane. The corrector group flattens that surface onto the sensor. The 0.79x element compresses the image scale at the same time, shortening the effective focal length and lowering the focal ratio, which shortens the exposure needed for a given signal.\u003c\/p\u003e\n\u003cp\u003eThe three-element, three-group construction is what allows both corrections to be made without reintroducing colour error at the edges. The consequence is that spacing tolerance drives corner star quality: the design is computed for one specific separation between the M54 thread and your sensor. Under-space it and corner stars elongate radially; over-space it and they elongate tangentially. The centre of the frame looks fine either way, which is why the corners are the place to check your work — and why the supplied gasket, which sets the spacing for you on the Fluorostar 156, is worth using as directed.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eDeep-sky astrophotography with a Fluorostar 156 in its reduced 0.79x configuration\u003c\/li\u003e\n  \u003cli\u003eFull-frame and APS-C cooled camera imaging where a flat field to the corners is required\u003c\/li\u003e\n  \u003cli\u003eWider framing than the Fluorostar 156 delivers natively — larger nebulae, extended galaxy fields\u003c\/li\u003e\n  \u003cli\u003eShorter sub-exposures at the same signal level, useful under mediocre guiding or shorter imaging windows\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eWilliam Optics publishes this corrector as the match for the \u003cstrong\u003eFluorostar 156\u003c\/strong\u003e. On the Fluorostar 156 it requires \u003cstrong\u003e55 mm of backfocus\u003c\/strong\u003e and needs \u003cstrong\u003eno adjustment\u003c\/strong\u003e — set the spacing with the supplied PVC gasket as directed. Backfocus is measured from the M54 x 0.75 camera-side thread to your sensor plane, and the total must account for every component in the train: filter drawer or filter wheel, off-axis guider, rotator, and the camera's own sensor-to-flange distance.\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/Flattener_back_focus-02.jpg?v=1784220246\" alt=\"William Optics flattener back focus diagram showing the 55 mm spacing measured from the M54 camera-side thread of the Ultra Flat 156\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\n\u003cp\u003eThe telescope side is \u003cstrong\u003eM92 x 1\u003c\/strong\u003e, threading straight to the Fluorostar 156. The camera side is \u003cstrong\u003eM54 x 0.75\u003c\/strong\u003e; most cooled astronomy cameras present an M48 or T2 interface, so confirm what your specific camera and filter hardware need to reach M54 and budget that adapter's optical length within the 55 mm figure — not on top of it. If you are not sure what your train adds up to, send us your camera and filter setup and we will work it out with you.\u003c\/p\u003e\n\u003cp\u003eWilliam Optics also publishes a back focus adjustment guide for the Ultra Flat series. If you are unsure which corrector matches a different William Optics telescope, contact us before ordering — the Fluorostar 132 uses the \u003ca href=\"\/products\/william-optics-ultra-flat-132-0-79x-reducer\"\u003eUltra Flat 132\u003c\/a\u003e, and the Fluorostar 156 is also listed as compatible with the FLAT 68III, FLAT 7A, and FLAT 8 correctors at their own respective reduction factors.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eImaging accessory:\u003c\/strong\u003e this is an optical corrector for astrophotography. It has no application in a visual train with an eyepiece.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMatched to the Fluorostar 156:\u003c\/strong\u003e the 43.2 mm image circle and 55 mm backfocus are the figures William Optics publishes for that telescope. Other William Optics refractors pair with their own correctors — if you are matching a different model, get in touch and we will confirm the right one.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSpacing matters:\u003c\/strong\u003e corner star shape depends on hitting the 55 mm backfocus. On the Fluorostar 156 the supplied PVC gasket sets it, with no further adjustment needed.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCamera-side adapter:\u003c\/strong\u003e the corrector presents M54 x 0.75, while most cooled cameras and filter wheels use M48 or T2. An adapter is usually needed and is sold separately — its optical length counts toward the 55 mm, not on top of it. We can help you identify the right one for your camera.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSensor coverage:\u003c\/strong\u003e the 43.2 mm corrected circle on the Fluorostar 156 covers a full-frame sensor (43.3 mm diagonal). Medium-format sensors are larger than that circle.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e at 1202 g it is worth accounting for in your focuser load and mount payload once the camera is attached.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWhat telescope does this work with?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eWilliam Optics lists it as the matched corrector for the Fluorostar 156, with a 43.2 mm image circle at 55 mm backfocus and no adjustment required.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo. On the Fluorostar 156 it threads straight to the M92 drawtube and the supplied PVC gasket sets the 55 mm spacing for you — there is no adjustment ring to dial in and no trial-and-error. The main thing to get right is the total distance from the M54 thread to your sensor, and we are happy to check that with you before you order.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use it for visual observing?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo. It is a reducer-flattener for imaging. It has no place in a visual train.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat backfocus do I need?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e55 mm, measured from the M54 x 0.75 camera-side thread to your sensor plane. Use the supplied PVC gasket as directed; the Fluorostar 156 pairing requires no further adjustment.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill it cover a full-frame sensor?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe published corrected image circle on the Fluorostar 156 is 43.2 mm. A full-frame sensor has a 43.3 mm diagonal, so the corrected field is sized to full frame. Larger medium-format sensors are outside that circle.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the difference between this and the Ultra Flat 132?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eBoth are 0.79x correctors, but they are computed for different telescopes: the Ultra Flat 132 is matched to the Fluorostar 132 and the Ultra Flat 156 to the Fluorostar 156. They are not interchangeable.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDo I need any additional adapters?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eVery likely on the camera side. The corrector presents M54 x 0.75; most cooled cameras and filter wheels use M48 or T2. Any adapter you add consumes part of the 55 mm backfocus budget. Tell us what camera you are running and we will point you to the right adapter.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes it change my focal length?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes — it multiplies the native focal length and focal ratio of the Fluorostar 156 by 0.79, which widens the field and shortens the exposure needed for a given signal.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: the matched 0.79x reducer-flattener for the Fluorostar 156. It threads on at M92, presents M54 to your camera, needs 55 mm of backfocus with the supplied gasket, and delivers a flat 43.2 mm field sized to a full-frame sensor. Spacing is the one figure worth measuring carefully — the corners are where it shows.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eOptical Diagram Reports\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eWilliam Optics publishes measured diagram reports for the Ultra Flat 156 on the Fluorostar 156. These show the corrected performance across the field rather than a marketing claim about it.\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FLT-156_Flat156-Diagram-1.jpg?v=1784220248\" alt=\"William Optics Ultra Flat 156 optical test diagram report for the Fluorostar 156 imaging system\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/FLT-156_Flat156-Diagram-2.jpg?v=1784220246\" alt=\"William Optics Ultra Flat 156 spot diagram report showing corrected star images across the 43.2 mm image circle\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154243870831,"sku":"P-FLAT156","price":1474.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-ultra-flat-156.jpg?v=1779654823"},{"product_id":"william-optics-flat-8-0-72x-reducer","title":"William Optics FLAT 8 0.72x Reducer","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics FLAT 8\u003c\/strong\u003e is a premium 0.72x reducer\/flattener for compatible William Optics refractors. It is designed to significantly reduce focal length, speed up the optical system, and help deliver a corrected imaging field for deep-sky astrophotography.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eBest for astrophotographers using compatible William Optics refractors who want a wider field of view and faster imaging speed than a standard 0.8x reducer.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e0.72x reduction:\u003c\/strong\u003e Creates a wider, faster imaging system.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eField correction:\u003c\/strong\u003e Helps improve star shape across the frame.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImaging-focused design:\u003c\/strong\u003e Built for deep-sky camera systems.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eWide-field deep-sky astrophotography\u003c\/li\u003e\n\u003cli\u003eLarge nebula imaging\u003c\/li\u003e\n\u003cli\u003eCompatible full-frame imaging systems\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eConfirm telescope compatibility, required adapter, camera thread, and backfocus spacing before imaging.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is an imaging accessory and requires precise spacing for best star correction.\u003c\/p\u003e\u003ch2\u003eOur Recommendation\u003c\/h2\u003e\u003cp\u003eChoose the FLAT 8 when your compatible William Optics refractor needs aggressive 0.72x focal reduction for wider and faster deep-sky imaging.\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154246000751,"sku":"P-FLAT8","price":1336.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-flat-8-reducer.jpg?v=1779654847"},{"product_id":"william-optics-flat-7a-0-8x-reducer-flattener","title":"William Optics FLAT 7A 0.8x Reducer Flattener","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics FLAT 7A\u003c\/strong\u003e is a 0.8x reducer\/flattener for compatible William Optics refractors. It is designed to widen the field of view, speed up the optical system, and improve edge-to-edge star correction for astrophotography.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eBest for astrophotographers using compatible William Optics refractors who want faster wide-field imaging and flatter stars across the frame.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e0.8x reduction:\u003c\/strong\u003e Widens the field and speeds up imaging.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eField correction:\u003c\/strong\u003e Helps improve corner star shape.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCamera-focused design:\u003c\/strong\u003e Built for deep-sky astrophotography systems.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eDeep-sky imaging\u003c\/li\u003e\n\u003cli\u003eWide-field astrophotography\u003c\/li\u003e\n\u003cli\u003eCompatible William Optics refractor setups\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eConfirm telescope compatibility, adapter thread, camera connection, and required backfocus spacing before imaging.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is an imaging accessory and requires correct spacing for best results.\u003c\/p\u003e\u003ch2\u003eOur Recommendation\u003c\/h2\u003e\u003cp\u003eChoose the FLAT 7A when your compatible William Optics refractor needs 0.8x focal reduction and field flattening for deep-sky imaging.\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154247901295,"sku":"P-FLAT7A","price":1087.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-flat-7a-reducer.jpg?v=1779654860"},{"product_id":"william-optics-54mm-flattener-extender-for-gt81-wifd","title":"William Optics 54mm Flattener Extender for GT81 WIFD","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics 54mm Flattener Extender for GT81 WIFD\u003c\/strong\u003e is a spacing adapter used to connect compatible William Optics flatteners and reducers to the Gran Turismo 81 WIFD imaging system.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eBest for astrophotographers using a GT81 WIFD who need the correct extension spacing for their flattener or reducer setup.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDedicated spacing adapter:\u003c\/strong\u003e Helps complete the correct imaging train.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGT81 WIFD compatibility:\u003c\/strong\u003e Designed for the William Optics GT81 WIFD system.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAstrophotography use:\u003c\/strong\u003e Supports proper camera spacing and field correction.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eGT81 WIFD flattener\/reducer setups\u003c\/li\u003e\n\u003cli\u003eDeep-sky astrophotography\u003c\/li\u003e\n\u003cli\u003eCamera spacing and adapter configuration\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eConfirm your exact telescope, flattener, reducer, and camera-side thread requirements before purchase.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is a mechanical adapter only. It does not provide optical correction by itself.\u003c\/p\u003e\u003ch2\u003eOur Recommendation\u003c\/h2\u003e\u003cp\u003eChoose this adapter when your GT81 WIFD imaging train requires the 54mm flattener extender shown in the William Optics compatibility table.\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154247999599,"sku":"M80-54-M48","price":95.2,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-54mm-flattener-extender-gt81-wifd.jpg?v=1779655062"},{"product_id":"william-optics-45mm-flattener-extender","title":"William Optics 45mm Flattener Extender","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics 45mm Flattener Extender\u003c\/strong\u003e is a mechanical extension adapter used to achieve the required spacing between compatible William Optics refractors, flatteners\/reducers, and camera systems.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eBest for astrophotographers configuring a William Optics imaging train that requires a 45mm extension adapter for the correct flattener or reducer spacing.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e45mm extension:\u003c\/strong\u003e Helps achieve proper mechanical spacing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAstrophotography setup support:\u003c\/strong\u003e Useful when configuring flatteners, reducers, and camera adapters.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWilliam Optics compatibility:\u003c\/strong\u003e Designed for compatible WO imaging systems.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eFlattener\/reducer spacing\u003c\/li\u003e\n\u003cli\u003eCamera train setup\u003c\/li\u003e\n\u003cli\u003eDeep-sky astrophotography accessories\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eConfirm your exact telescope, flattener\/reducer, and camera thread requirements before purchase.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is a mechanical adapter only. 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It does not provide optical correction by itself.\u003c\/p\u003e\u003ch2\u003eOur Recommendation\u003c\/h2\u003e\u003cp\u003eChoose this adapter when you need a 2-inch push-in nosepiece connection for a compatible William Optics FLAT 6AIII imaging train.\u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":53154251145327,"sku":"YE-M63F-2IN-PI","price":82.6,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/william-optics-2-inch-push-in-nosepiece-m63-adapter-flat6aiii.jpg?v=1779655111"},{"product_id":"william-optics-flat4-draw-tube-adapter","title":"William Optics Flat4 Draw Tube Adapter","description":"\u003cp\u003eThe \u003cstrong\u003eWilliam Optics Flat4 Draw Tube Adapter\u003c\/strong\u003e is a mechanical adapter used to connect compatible William Optics draw tubes, focusers, flatteners, reducers, and imaging accessories.\u003c\/p\u003e\u003ch2\u003eWho Is This Product Best For?\u003c\/h2\u003e\u003cp\u003eBest for astrophotographers configuring a William Optics imaging train that requires the Flat4 draw tube adapter for proper mechanical compatibility.\u003c\/p\u003e\u003ch2\u003eWhy Choose This Product?\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDraw tube adapter:\u003c\/strong\u003e Helps connect compatible William Optics imaging components.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMechanical compatibility:\u003c\/strong\u003e Supports proper flattener\/reducer installation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAstrophotography setup support:\u003c\/strong\u003e Useful when configuring camera spacing and accessory fit.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eFlattener\/reducer adapter setup\u003c\/li\u003e\n\u003cli\u003eCamera train configuration\u003c\/li\u003e\n\u003cli\u003eWilliam Optics refractor imaging systems\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eConfirm your telescope, focuser, flattener\/reducer, and camera adapter requirements before purchase.\u003c\/p\u003e\u003ch2\u003eImportant Limitations\u003c\/h2\u003e\u003cp\u003eThis is a mechanical adapter only. 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