{"title":"William Optics Cat Series Telescopes","description":"\u003cp\u003eThe William Optics Cat series is a family of compact Petzval refractors built for wide-field astrophotography, with a flat field that works without a separate flattener. Most models use the WIFD internal focusing design.\u003c\/p\u003e\u003cp\u003eThe line runs from the MiniCat 51 at f\/3.5 and the RedCat 51, 61 and 71 to the Cat 91 and the UltraCat 56, 76 and 108 at f\/4.8, up to the UltraCat 131. Cat mounting rings and a saddle handle bar are also available.\u003c\/p\u003e","products":[{"product_id":"william-optics-cat-mounting-ring","title":"William Optics Cat Mounting Ring","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e50mm Inner Diameter\u003c\/li\u003e\n\u003cli\u003eSolid Aluminum Construction\u003c\/li\u003e\n\u003cli\u003eAnodized Blue Finish\u003c\/li\u003e\n\u003cli\u003e1\/4\"-20 Threaded Mounting Holes\u003c\/li\u003e\n\u003cli\u003eWeight: 4.9 oz (140 g)\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\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\u003eWilliam Optics Cat Mounting Ring\u003c\/h2\u003e\n      \u003cp\u003eThe William Optics Cat Mounting Ring is a secure, custom-fit mounting point for telescope tubes with a precise 50mm outer diameter. Machined from solid aluminum and weighing just 4.9 oz (140 g), it adds minimal weight while offering standard 1\/4\"-20 threaded holes for attaching to dovetail bars or other accessories.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003ePrecision-Machined for a 50mm Tube Diameter\u003c\/h3\u003e\n      \u003cp\u003eThis is not a one-size-fits-most solution. The William Optics Cat ring is engineered for an exact 50mm tube diameter, ensuring a rigid, non-slip connection without marring your telescope's finish. The solid aluminum construction prevents the flexure that can ruin a long exposure when using the ring for a guide scope.\u003c\/p\u003e\n      \u003cp\u003eBecause the fit is so precise, you must verify your telescope's dimensions before purchasing. These rings are manufactured with zero tolerance for tubes larger than 50mm—even a 1mm difference will prevent a fit. We strongly advise using calipers to measure your optical tube directly rather than relying on published specifications, which can change between production runs.\u003c\/p\u003e\n      \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eSolid Aluminum Construction:\u003c\/strong\u003e Machined from a single block for maximum rigidity and zero flexure, weighing only 4.9 oz (140 g).\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003e50mm Inner Diameter:\u003c\/strong\u003e Designed for a perfect, non-marring fit on telescope tubes with an exact 50mm outer diameter.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eAnodized Blue Finish:\u003c\/strong\u003e Provides a durable, corrosion-resistant surface that matches William Optics' distinctive aesthetic.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003e1\/4\"-20 Mounting Holes:\u003c\/strong\u003e Offers standard threading for secure attachment to Vixen or Losmandy style dovetail plates.\u003c\/li\u003e\n      \u003c\/ul\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n\n\u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWill the William Optics Cat Mounting Ring fit my telescope?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThis ring is designed exclusively for any optical tube with an \u003cstrong\u003eexact 50mm outer diameter\u003c\/strong\u003e. Because manufacturer specifications can change without notice, you must physically measure your telescope's tube with calipers to confirm the size before purchasing. Do not rely on published specs alone.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eMy telescope tube is 51mm. Can I make the William Optics 50mm ring fit?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003e\u003cstrong\u003eAbsolutely not.\u003c\/strong\u003e The ring has a precise 50mm inner diameter with no tolerance for larger tubes. Attempting to force it onto a 51mm tube will damage the ring, your telescope's finish, or both. You must have an exact 50mm tube for this ring to fit correctly.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eIs the William Optics Cat Mounting Ring sold as a single unit or a pair?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe William Optics Cat Mounting Ring is sold as a \u003cstrong\u003esingle unit\u003c\/strong\u003e. If you need a pair to mount a longer optical tube or a guide scope, you will need to purchase a quantity of two.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eI'm building a custom guide scope setup with a 50mm finder. Is this William Optics ring a good choice?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes, this is an excellent application. The ring's solid aluminum build provides a rigid, flex-free platform for a 50mm guide scope, ensuring there is no differential flexure between your main telescope and your autoguiding system during an imaging session.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat are the mounting holes on the William Optics Cat ring for?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe ring features standard \u003cstrong\u003e1\/4\"-20 threaded holes\u003c\/strong\u003e. This is the most common thread size in photography and astronomy, allowing you to attach the ring securely to most Vixen-style or Losmandy-style dovetail plates, as well as other astronomical accessories.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the William Optics Cat Mounting Ring made of?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eIt is machined from a single piece of \u003cstrong\u003esolid aluminum\u003c\/strong\u003e and features a durable, anodized blue finish. This construction ensures it is both lightweight at just 4.9 oz (140 g) and extremely rigid.\u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003ctable class=\"DAV-specifications\"\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eSKU\u003c\/td\u003e\n\u003ctd\u003eWO-M-MR50RC-BL\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eInner Diameter\u003c\/td\u003e\n\u003ctd\u003e50mm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eMaterial\u003c\/td\u003e\n\u003ctd\u003eSolid Aluminum\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eFinish\u003c\/td\u003e\n\u003ctd\u003eAnodized Blue\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eMounting Holes\u003c\/td\u003e\n\u003ctd\u003e1\/4\"-20 Threaded\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e4.9 oz (140 g)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cul class=\"DAV-grid\"\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003e50mm Cat Mounting Ring\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44967241318685,"sku":"WO-M-MR50RC-BL","price":69.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/products\/William-Optics-Cat-Mounting-Ring-M-MR50RC-BL-1__75660.1596133325.1280.1280.jpg?v=1684339670"},{"product_id":"william-optics-cat-series-saddle-handle-bar","title":"William Optics Cat Series Saddle Handle Bar","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eLength: 107 mm\u003c\/li\u003e\n\u003cli\u003eIntegrated Mini-Vixen Style Saddle\u003c\/li\u003e\n\u003cli\u003eWeight: 0.12 kg \/ 0.26 lbs\u003c\/li\u003e\n\u003cli\u003eDesigned for William Optics Cat Series Telescopes\u003c\/li\u003e\n\u003cli\u003eAdds a carrying handle and accessory mounting point\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\u003eWilliam Optics Cat Series Saddle Handle Bar\u003c\/h2\u003e\n\u003cp\u003eAdd a secure grip and a vital accessory mounting point to your William Optics Cat series telescope with the Cat Series Saddle Handle Bar, a compact 107 mm bar that integrates a Mini-Vixen style saddle and weighs just 0.12 kg (0.26 lbs). This handle is engineered to perfectly complement the fit, finish, and portability of your Cat series refractor, adding significant functionality without compromising your setup's balance.\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\u003eA 107mm Handle with an Integrated Mini-Vixen Saddle\u003c\/h3\u003e\n\u003cp\u003eThis handle bar is a dual-purpose upgrade for your portable imaging rig. The integrated Mini-Vixen saddle provides a secure and convenient mounting point for guide scopes, finderscopes, or other small accessories, keeping your setup compact and organized. At just 107 mm in length and 44 mm in width, it fits perfectly on William Optics Cat series refractors without adding unnecessary bulk or weight.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDual-Purpose Design:\u003c\/strong\u003e Combines a sturdy, comfortable carrying handle with a functional Mini-Vixen saddle for accessories.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLightweight Construction:\u003c\/strong\u003e Weighs only 0.12 kg (0.26 lbs), preserving the critical balance of your portable telescope setup on a star tracker or small mount.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompact Form Factor:\u003c\/strong\u003e The 107 mm length is scaled specifically for the compact optical tubes of the RedCat, SpaceCat, and WhiteCat telescopes.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSecure Accessory Mounting:\u003c\/strong\u003e The Mini-Vixen saddle is the industry standard for lightweight accessories, making it ideal for attaching guide scopes like the William Optics UniGuide or other compatible finders.\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\"\u003eWhat telescopes is the William Optics Cat Series Saddle Handle Bar designed for?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis handle bar is specifically designed to match the mounting points and aesthetics of the William Optics \"Cat\" series of petzval refractors, including the RedCat, SpaceCat, and WhiteCat models.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat kind of accessories can I mount on the Cat Series Handle Bar's saddle?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe integrated \u003cstrong\u003eMini-Vixen style saddle\u003c\/strong\u003e is perfect for mounting lightweight accessories that use a corresponding dovetail bar. This typically includes guide scopes (such as the 32mm or 50mm William Optics UniGuide), red dot finders, or other small pointing devices.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Cat Series Handle Bar affect the balance of my RedCat 51 on a portable mount?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAt just \u003cstrong\u003e0.12 kg (0.26 lbs)\u003c\/strong\u003e, the handle bar adds minimal weight to your optical tube. It is unlikely to significantly affect the balance of a RedCat 51 on a capable star tracker or small equatorial mount, but you should always re-balance your entire system after adding or removing any accessory.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow long is the William Optics Cat Series Handle Bar?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe handle bar measures \u003cstrong\u003e107 mm\u003c\/strong\u003e in length, making it a compact addition that matches the scale of the Cat series telescopes and provides a secure grip without being cumbersome.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I mount a heavy guide scope to the Cat Series Handle Bar?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile the Mini-Vixen saddle is secure, the handle's primary purpose is for lightweight accessories. Mounting a heavy guide scope (e.g., a full 80mm refractor) is not recommended, as it could introduce flexure into your imaging train and place undue stress on the handle and the telescope's mounting points.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes the color of the Cat Series Saddle Handle Bar match the telescope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, the handle bar is available in multiple colors, including red and black, which are anodized to match the distinctive finish of the William Optics Cat series telescopes, ensuring a seamless and professional look.\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\u003eLength\u003c\/td\u003e\n\u003ctd\u003e107 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWidth\u003c\/td\u003e\n\u003ctd\u003e44 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDovetail Type\u003c\/td\u003e\n\u003ctd\u003eMini-Vixen\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e0.12 kg \/ 0.26 lbs\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\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eWilliam Optics Cat Series Saddle Handle Bar\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Red","offer_id":44967243514141,"sku":"WO-M-HCRC-RD","price":83.0,"currency_code":"CAD","in_stock":true},{"title":"Black","offer_id":44967243546909,"sku":"WO-M-HCRC-BL","price":83.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/products\/William-Optics-Cat-Series-Saddle-Handle-Bar-M-HCRC-1__20520.1596133330.1280.1280.jpg?v=1684339494"},{"product_id":"william-optics-redcat-61-petzval-wifd","title":"William Optics RedCat 61 WIFD","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e61mm Aperture Petzval-like Astrograph\u003c\/li\u003e\n\u003cli\u003eFast f\/4.9 Focal Ratio\u003c\/li\u003e\n\u003cli\u003eWIFD (William Optics Internal Focus Design) Focuser\u003c\/li\u003e\n\u003cli\u003eRequires No Backfocus Calculation\u003c\/li\u003e\n\u003cli\u003eFull Frame Image Circle\u003c\/li\u003e\n\u003cli\u003eIntegrated Dual Vixen\/Arca-Swiss Mounting Plate\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\u003eWilliam Optics RedCat 61 WIFD\u003c\/h2\u003e\n\u003cp\u003eThe William Optics RedCat 61 WIFD is a premium 61mm f\/4.9 Petzval-like astrograph engineered for wide-field imaging, delivering a flat, color-corrected field across a full-frame sensor without the need for complex backfocus calculations.\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\u003eA 61mm f\/4.9 Petzval-like Optical System\u003c\/h3\u003e\n\u003cp\u003eThe heart of the RedCat 61 is its 61mm Petzval-like optical design, which produces a flat field of view without needing an additional flattener. At a fast focal ratio of f\/4.9, you can capture significant detail on faint nebulae and galaxies with shorter exposure times, reducing tracking demands on your mount. This integrated design ensures sharp, pinpoint stars from the center to the corners of your frame.\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\u003eWilliam Optics WIFD: A Zero-Flexure Internal Focuser\u003c\/h3\u003e\n\u003cp\u003eThis RedCat model incorporates the William Optics Internal Focus Design (WIFD), a major upgrade for imagers. Unlike traditional focusers that move the camera and can introduce sag or tilt, the WIFD moves the optics internally. This mechanism provides exceptionally fine control and ensures the imaging train remains perfectly rigid and orthogonal to the focal plane, even when loaded with heavy cameras and filter wheels.\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\u003eM48 Direct-Connect: Imaging Without Backfocus Spacing\u003c\/h3\u003e\n\u003cp\u003eOne of the most significant advantages of the RedCat 61 is its simplicity. The Petzval design eliminates the need to calculate and set a precise backfocus distance. You simply attach your DSLR, mirrorless, or dedicated astronomy camera to the included M48 adapter, focus, and start imaging. This removes a common point of failure and frustration from the astrophotography process, getting you to a successful result faster.\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\u003eIntegrated Mounting: The 2-in-1 Vixen\/Arca Plate\u003c\/h3\u003e\n\u003cp\u003eThe RedCat 61 is built for the field. It features a CNC-machined tube ring connected to a dual-style mounting plate compatible with both Vixen-style saddles and Arca-Swiss tripod heads out of the box. An integrated handle bar makes transport easy and doubles as a mounting point for a guide scope. The entire package fits into a custom soft carry case, making it an ideal grab-and-go imaging instrument.\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\u003eRedCat 61 vs. RedCat 51: 10mm More Aperture for Deeper Views\u003c\/h3\u003e\n\u003cp\u003eWhile both astrographs share the same f\/4.9 Petzval design and legendary ease of use, the RedCat 61 offers a distinct advantage in light-gathering power and image scale over its 51mm sibling.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eRedCat 51 Advantage:\u003c\/strong\u003e The RedCat 51 offers a wider true field of view, making it better suited for capturing immense targets like the entire North America Nebula (NGC 7000) or the full expanse of the Rho Ophiuchi cloud complex in a single frame.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRedCat 61 Advantage:\u003c\/strong\u003e With a 61mm aperture, the RedCat 61 gathers nearly 44% more light, allowing for deeper images or shorter total integration times. Its longer focal length provides a tighter field of view, which is ideal for framing medium-sized targets like the Andromeda Galaxy (M31) or the Pleiades (M45) with more resolution and impact.\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\"\u003eDo I need a field flattener for the William Optics RedCat 61 WIFD?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. The \u003cstrong\u003ePetzval-like optical design\u003c\/strong\u003e of the RedCat 61 provides a flat field natively, so no additional field flattener or reducer is required. This simplifies the imaging train and ensures optimal correction out of the box.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the main advantage of the RedCat 61's WIFD focuser?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe William Optics Internal Focus Design (WIFD) moves the optical elements internally rather than moving the camera externally. This provides two key benefits:\n\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eZero Flexure:\u003c\/strong\u003e It prevents sag and tilt, which can occur with heavy cameras on traditional drawtube focusers, ensuring a perfectly flat focal plane.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFixed Camera Position:\u003c\/strong\u003e The camera does not move during focusing, which helps with cable management and maintaining balance.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I mount the RedCat 61 to my equatorial mount?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe RedCat 61 includes an integrated \u003cstrong\u003edual-side mounting plate\u003c\/strong\u003e. This plate is directly compatible with standard \u003cstrong\u003eVixen-style\u003c\/strong\u003e saddles found on most equatorial mounts, as well as \u003cstrong\u003eArca-Swiss\u003c\/strong\u003e heads used on photographic tripods.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow would the RedCat 61 perform on the Andromeda Galaxy (M31) with a full-frame camera?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe RedCat 61 is an excellent choice for imaging the Andromeda Galaxy (M31) with a full-frame camera. Its focal length is ideal for framing the galaxy's core and sprawling spiral arms, while the flat field ensures that stars in the corners of the large sensor remain sharp and round.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the RedCat 61 a good choice for imaging the Pleiades (M45) from a portable setup?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, it's a perfect match. The Pleiades (M45) star cluster and its surrounding reflection nebulosity fit beautifully within the RedCat 61's field of view. Its compact size, f\/4.9 speed, and included soft carry case make it an ideal instrument for portable setups on a star tracker or small equatorial mount.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the William Optics RedCat 61 good for viewing planets like Jupiter or Saturn?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, the RedCat 61 is not designed for high-magnification planetary viewing or imaging. As a fast f\/4.9 astrograph with a short focal length, it excels at capturing wide-field deep-sky objects. For planets, a telescope with a much longer focal length, like a Schmidt-Cassegrain or Maksutov-Cassegrain, is recommended.\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\u003eAperture\u003c\/td\u003e\n\u003ctd\u003e61mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/4.9\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Design\u003c\/td\u003e\n\u003ctd\u003ePetzval-like Astrograph\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003eWIFD (William Optics Internal Focus Design)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eImage Circle\u003c\/td\u003e\n\u003ctd\u003eFull Frame (44mm+)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCamera Connection\u003c\/td\u003e\n\u003ctd\u003eM48x0.75 Male Thread\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting Plate\u003c\/td\u003e\n\u003ctd\u003eDual Sided: Vixen-style and Arca-Swiss\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\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eRedCat 61 Main Tube\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003ePatented Bahtinov Mask Cap\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eM48 Camera Adapter\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDual-side Vixen\/Arca Mounting Plate\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eMounting Ring \u0026amp; Handle Bar\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSoft Carry Case\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eAllen Key Set\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":45020060057885,"sku":"WO-T-C-61RD","price":1581.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-Redcat-61-1_da09ecb6-9960-4cc2-89cf-f05dc3c84480.jpg?v=1722275824"},{"product_id":"william-optics-redcat-51-wifd","title":"William Optics Redcat 51 WIFD","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eCompact Apochromatic Refractor\u003c\/li\u003e\n\u003cli\u003ePetzval-like Optical Design for Flat Fields\u003c\/li\u003e\n\u003cli\u003eWilliam Optics Internal Focus Design (WIFD)\u003c\/li\u003e\n\u003cli\u003eCNC-Machined Aluminum Body\u003c\/li\u003e\n\u003cli\u003eIntegrated Mounting Ring, Handle, and Dual Vixen\/Arca-Swiss Plate\u003c\/li\u003e\n\u003cli\u003eDesigned for Hassle-Free Astrophotography\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\u003eWilliam Optics Redcat 51 WIFD\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Redcat 51 WIFD combines a fast, wide-field optical system with a robust internal focuser, creating a portable imaging platform built for capturing expansive celestial targets. This Petzval-like apochromatic refractor simplifies astrophotography by delivering a sharp, flat field across your camera sensor without the need for complex back focus calculations, making the Redcat 51 a powerful tool for both beginners and seasoned imagers.\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\u003eRedcat 51: A Wide-Field Petzval-like Optical Design\u003c\/h3\u003e\n\u003cp\u003eThe heart of the Redcat 51 is its Petzval-like apochromatic optical system. This design uses an integrated flattener to produce pinpoint stars across a wide, corrected image circle, eliminating the need for a separate field flattener accessory. This makes it an ideal instrument for capturing large-scale celestial objects like the Andromeda Galaxy (M31) or the entire Veil Nebula complex in a single frame.\u003c\/p\u003e\n\u003cp\u003eBecause the optical correction is built-in, you can connect your camera directly using the included M48 adapter and start imaging immediately. This \"point-and-shoot\" simplicity removes one of the most common points of failure in an astrophotography setup—achieving correct sensor spacing.\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\u003eThe WIFD Focuser: Precision Internal Focusing\u003c\/h3\u003e\n\u003cp\u003eThis version of the Redcat 51 features the William Optics Internal Focus Design (WIFD). Unlike traditional focusers that move the camera outward, the WIFD system adjusts focus by moving optical elements internally. This design offers two critical advantages for imaging: it eliminates image shift during focusing and prevents the camera from rotating, maintaining your target's framing perfectly.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eZero Image Shift:\u003c\/strong\u003e The internal mechanism provides a solid, stable platform for your camera, ensuring that focus adjustments are smooth and precise without tilting the imaging train.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFixed Rotational Angle:\u003c\/strong\u003e Your camera and any attached accessories remain fixed in position, which is essential for maintaining guide star calibration and consistent mosaic framing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFine Control:\u003c\/strong\u003e The focuser allows for the minute adjustments necessary to achieve critical focus, enhancing the sharpness and detail in your final images.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCNC-Machined Build: The Redcat 51's Go-Anywhere Chassis\u003c\/h3\u003e\n\u003cp\u003eCrafted from a solid block of CNC-machined aluminum, the Redcat 51 WIFD is both rugged and highly portable. The entire assembly is engineered for travel and quick setup on lightweight star trackers or full equatorial mounts. The integrated mounting ring, handle bar, and dual-spec mounting plate provide a complete, ready-to-use system out of the box.\u003c\/p\u003e\n\u003cp\u003eThe dual Vixen and Arca-Swiss compatible mounting plate allows you to attach the telescope to virtually any astronomical mount or even a standard photographic tripod. This versatility makes the Redcat 51 an excellent choice for a grab-and-go deep-sky setup or a high-end telephoto lens for terrestrial photography.\u003c\/p\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\"\u003eWhat is the main advantage of the Redcat 51 WIFD's internal focuser?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe main advantage of the William Optics Internal Focus Design (WIFD) is stability. By moving the optics internally, it prevents the camera and imaging train from moving or rotating. This eliminates image shift and maintains perfect framing, which is critical for sharp, automated astrophotography sequences.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDo I need a field flattener with the William Optics Redcat 51?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, you do not. The Redcat 51 uses a Petzval-like optical design that has a field flattener built into the optical tube. This provides a flat, corrected field out of the box, so you can attach your camera directly without worrying about additional accessories or back focus spacing.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I mount the Redcat 51 WIFD to my tripod or mount?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Redcat 51 WIFD includes a dual-spec mounting plate. This plate is compatible with both standard \u003cstrong\u003eVixen-style\u003c\/strong\u003e saddles found on most astronomy mounts and \u003cstrong\u003eArca-Swiss\u003c\/strong\u003e clamps used on high-end photographic tripods, offering maximum mounting flexibility.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the Redcat 51 a good telescope for viewing planets like Jupiter or Saturn?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile you can see planets with the Redcat 51, it is not its primary purpose. Its short focal length and wide field of view are optimized for deep-sky objects like nebulae and galaxies. For detailed planetary viewing, a telescope with a much longer focal length, such as a Schmidt-Cassegrain or Maksutov-Cassegrain, would be a better choice.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the Redcat 51 WIFD perform on large targets like the North American Nebula (NGC 7000)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Redcat 51 WIFD excels at imaging very large targets like the North American Nebula (NGC 7000) or the Andromeda Galaxy (M31). Its wide, flat field of view is designed specifically to capture these massive structures in their entirety, making it a premier instrument for wide-field mosaics and all-sky imaging.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the Redcat 51 WIFD suitable for a portable setup on a small star tracker?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. Its compact size, light weight, and robust, self-contained design make the Redcat 51 WIFD an ideal choice for pairing with a portable star tracker. This combination creates a powerful, airline-friendly deep-sky astrophotography rig that you can take to dark sky sites anywhere in the world.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eRedcat 51 WIFD Main Tube\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBahtinov Mask Cap\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eM48 Camera Adapter\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDual-side Vixen\/Arca-Swiss Plate\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eMounting Ring \u0026amp; Handle Bar\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSoft Carry Case\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eAllen Key Set\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":47333310202141,"sku":"WO-L-RC51RDIII","price":1225.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-Redcat-51-WIFD-1.jpg?v=1724263856"},{"product_id":"william-optics-redcat-71-wifd","title":"William Optics Redcat 71 WIFD","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eApochromatic Petzval-like Optical Design\u003c\/li\u003e\n\u003cli\u003eWIFD (William Optics Internal Focuser Design)\u003c\/li\u003e\n\u003cli\u003eIntegrated Bahtinov Mask in Dust Cap\u003c\/li\u003e\n\u003cli\u003eIncluded M48 Camera Adapter\u003c\/li\u003e\n\u003cli\u003eDual Vixen\/Arca-Swiss Mounting Plate\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\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\u003eWilliam Optics Redcat 71 WIFD\u003c\/h2\u003e\n      \u003cp\u003eThe William Optics Redcat 71 WIFD is a premium apochromatic refractor designed for the discerning astrophotographer seeking a larger aperture in a portable, flat-field instrument. Its Petzval-like optical system corrects for field curvature across a wide imaging circle, delivering sharp, color-pure stars from edge to edge without the need for a separate field flattener. This design, combined with a fast focal ratio, illuminates faint, extended deep-sky objects like the North American Nebula (NGC 7000) with exceptional clarity and contrast.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eApochromatic Petzval-like Optics for Flat-Field Imaging\u003c\/h3\u003e\n      \u003cp\u003eThe core of the Redcat 71 is its four-element Petzval-like lens arrangement. This sophisticated optical design acts as its own flattener, a critical advantage for astrophotography. You can connect your DSLR or dedicated astronomy camera and achieve a flat, corrected field of view right out of the box, eliminating the complexity and potential spacing errors of using an external flattener.\u003c\/p\u003e\n      \u003cp\u003eAs an apochromatic refractor, the Redcat 71 uses specialized glass to bring all colors of the visual spectrum to a single, sharp focus. This prevents the distracting purple fringing around bright stars common in simpler designs, ensuring your star fields are rendered with natural, high-fidelity color.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n    \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eWIFD Internal Focuser for Zero Image Shift\u003c\/h3\u003e\n      \u003cp\u003eA key innovation in the Redcat 71 is the William Optics Internal Focuser Design (WIFD). Unlike traditional drawtube focusers that move the camera, the WIFD system moves the optical elements internally. This design completely eliminates image shift and focuser sag, even when using heavy imaging trains with filter wheels and off-axis guiders.\u003c\/p\u003e\n       \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eMaximum Stability:\u003c\/strong\u003e Your camera and accessories remain fixed, maintaining perfect optical alignment throughout the focusing process for consistently sharp results.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003ePrecise Adjustments:\u003c\/strong\u003e The robust mechanism allows for smooth, meticulous focus control, which is essential for achieving critical sharpness on high-resolution sensors.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eIntegrated Bahtinov Mask:\u003c\/strong\u003e To aid in this process, the dust cap features an integrated Bahtinov mask, providing a simple and highly accurate method for reaching perfect focus every time.\u003c\/li\u003e\n      \u003c\/ul\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eCNC-Machined Build and Integrated Mounting System\u003c\/h3\u003e\n      \u003cp\u003eCrafted from solid CNC-machined aluminum, the Redcat 71 WIFD is built for both durability and portability. The entire package is designed to be field-ready, with an integrated mounting system that provides immediate compatibility with a wide range of equatorial mounts and accessories. The included soft carry case makes it an ideal instrument for traveling to dark-sky sites.\u003c\/p\u003e\n      \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eDual Dovetail Plate:\u003c\/strong\u003e The mounting ring is attached to a versatile plate that features both a Vixen-style and Arca-Swiss rail, allowing you to connect to nearly any modern mount without extra hardware.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eMulti-function Handlebar:\u003c\/strong\u003e The top handle not only makes the telescope easy to carry but also doubles as a mounting saddle for guide scopes or other accessories.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eCamera Connection:\u003c\/strong\u003e The included M48 adapter provides a standard, wide-aperture connection point for most astronomy cameras and DSLR M48 T-rings.\u003c\/li\u003e\n      \u003c\/ul\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eRedcat 71 vs. Redcat 51: More Aperture for Deeper Views\u003c\/h3\u003e\n      \u003cp\u003eThe Redcat 71 is the direct step-up from the legendary Redcat 51, designed for imagers who are ready for more resolving power and light-gathering capability.\u003c\/p\u003e\n      \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eRedcat 51's Advantage:\u003c\/strong\u003e The smaller Redcat 51 remains the champion of ultimate portability, fitting in a camera bag and being perfectly suited for lightweight star trackers.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eRedcat 71's Advantage:\u003c\/strong\u003e The Redcat 71's larger aperture gathers significantly more light. This translates directly to brighter images, shorter exposure times, and the ability to resolve finer details in galactic dust lanes and faint nebulae. It represents a tangible increase in imaging power while maintaining the grab-and-go convenience the Redcat series is known for.\u003c\/li\u003e\n      \u003c\/ul\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eDo I need a field flattener for the William Optics Redcat 71?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eNo, you do not. The \u003cstrong\u003ePetzval-like optical design\u003c\/strong\u003e of the Redcat 71 has a built-in field flattener. This provides a flat, corrected field of view across a large image circle, ensuring sharp stars from corner to corner without requiring any additional accessories.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the benefit of the WIFD focuser on the Redcat 71?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe \u003cstrong\u003eWIFD (William Optics Internal Focuser Design)\u003c\/strong\u003e is a major upgrade for astrophotography. By moving the optics internally instead of the camera, it offers two key benefits:\u003c\/p\u003e\n    \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eZero image shift or tilt:\u003c\/strong\u003e It prevents the camera from sagging or tilting, which is a common issue with heavy imaging setups on traditional focusers.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eEnhanced stability:\u003c\/strong\u003e It creates a rigid, stable imaging train, which is critical for maintaining sharp focus over long exposures.\u003c\/li\u003e\n    \u003c\/ul\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the Redcat 71 WIFD perform on large targets like the Andromeda Galaxy (M31)?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe Redcat 71 WIFD is an excellent choice for very large celestial objects. Its wide, flat field of view is ideal for framing the entirety of massive targets like the Andromeda Galaxy (M31) or the North American Nebula (NGC 7000), especially when paired with an APS-C or full-frame sensor.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Redcat 71 WIFD visually on a portable mount?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes. While optimized for imaging, the Redcat 71's fast, high-contrast optics make it a superb rich-field telescope for visual use. Its compact size and the included soft case make it a great travel scope. It pairs well with sturdy portable mounts and star trackers, but you should always confirm your mount's payload capacity.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat kind of dovetail plate does the Redcat 71 come with?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe Redcat 71 includes a versatile \u003cstrong\u003edual-side dovetail plate\u003c\/strong\u003e. One side is a standard Vixen-style rail, and the other is an Arca-Swiss rail, providing native compatibility with a wide variety of astronomical mounts and photographic tripods without needing extra adapters.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I achieve perfect focus with the Redcat 71 WIFD?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe Redcat 71 makes critical focusing simple. The lens cap has an \u003cstrong\u003eintegrated Bahtinov mask\u003c\/strong\u003e. Simply place the cap on the front of the telescope, point at a bright star, and adjust the WIFD focuser until the central diffraction spike is perfectly centered between the other two spikes.\u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003ctable class=\"DAV-specifications\"\u003e\n    \u003ctbody\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cul class=\"DAV-grid\"\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eMain Tube\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eBahtinov Cap\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eM48 Camera Adapter\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eDual-side Plate\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eMounting Ring \u0026amp; Handle bar\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eSoft Carry Case\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n    \u003cli class=\"DAV-grid-item\"\u003e\n      \u003cdiv\u003e\n        \u003cp class=\"DAV-item-title\"\u003eAllen Key Set\u003c\/p\u003e\n        \u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n      \u003c\/div\u003e\n    \u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":47333326749981,"sku":"WO-T-C-71RDII","price":2013.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Redcat-71-WIFD-perspective-1.webp?v=1722275887"},{"product_id":"william-optics-minicat-51-wifd","title":"William Optics MiniCat 51 WIFD f\/3.5","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e51mm Aperture Diameter\u003c\/li\u003e\n\u003cli\u003e178mm Focal Length\u003c\/li\u003e\n\u003cli\u003ef\/3.5 Focal Ratio\u003c\/li\u003e\n\u003cli\u003e6-Element Petzval Optical Design\u003c\/li\u003e\n\u003cli\u003e43.2mm Full-Frame Image Circle\u003c\/li\u003e\n\u003cli\u003eWIFD Rack \u0026amp; Pinion Focuser\u003c\/li\u003e\n\u003cli\u003e1.67 kg OTA Weight\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\u003eWilliam Optics MiniCat 51 WIFD f\/3.5 Astrograph\u003c\/h2\u003e\n\u003cp\u003eThe William Optics MiniCat 51 WIFD combines an extremely fast f\/3.5 focal ratio with a 178mm focal length in a 6-element Petzval design engineered for wide-field astrophotography. Its optical train, featuring two Super ED glass elements, produces a flat 43.2mm image circle that fully illuminates full-frame sensors without requiring an additional flattener. Weighing just 1.67 kg, the MiniCat 51 delivers a portable, high-speed imaging platform ready for any location.\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\u003e6-Element f\/3.5 Petzval Optics: A 43.2mm Flat Field\u003c\/h3\u003e\n\u003cp\u003eThe MiniCat 51's optical system is built for one purpose: capturing immense swaths of the night sky with exceptional color correction and sharpness. The 6-element Petzval layout corrects for field curvature internally, meaning you get pinpoint stars across a 43.2mm image circle without the complexity of a separate flattener. Two Super ED elements minimize chromatic aberration, ensuring clean, high-contrast images of targets like the North American Nebula (NGC 7000) or the Andromeda Galaxy (M31).\u003c\/p\u003e\n\u003cp\u003eAt an aggressive f\/3.5 focal ratio, this astrograph gathers light significantly faster than typical f\/5 or f\/6 refractors. This allows you to collect more signal in less time, reducing the demands on your mount's tracking and enabling deeper images from a single night's session.\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\u003ePatented WIFD Focuser: 28mm of Tilt-Free Travel\u003c\/h3\u003e\n\u003cp\u003eWilliam Optics' patented Internal Focus Design (WIFD) is a robust rack-and-pinion mechanism built to handle modern imaging payloads without flexure or tilt. The entire focusing mechanism moves internally, providing 28mm of precise travel while maintaining perfect optical alignment. This design is critical for maintaining a flat field, as it prevents the drawtube sag that can compromise edge-of-field star shapes.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eEAF Compatible:\u003c\/strong\u003e The focuser is designed for seamless integration with the ZWO EAF and other popular electronic focusers for automated, repeatable focusing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFlexible Back Spacing:\u003c\/strong\u003e With a working distance of 58mm to 30mm, you have ample room to incorporate filter wheels, off-axis guiders, and other accessories into your imaging train.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncluded Rotator \u0026amp; Tilt Adapter:\u003c\/strong\u003e The package includes a camera angle rotator and tilt adjuster, giving you full control over framing and sensor plane alignment right out of the box.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eVixen \u0026amp; Arca-Swiss Mounting: 1.67 kg for Any Mount\u003c\/h3\u003e\n\u003cp\u003eEngineered for portability, the MiniCat 51 OTA weighs a mere 1.67 kg and has a compact 210mm tube length. This makes it an ideal match for lightweight star trackers and portable GoTo mounts, allowing you to build a powerful imaging rig that travels easily. The integrated dual-spec dovetail plate provides native compatibility with both traditional Vixen-style saddles and modern Arca-Swiss tripod heads, offering maximum flexibility for mounting.\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\u003eMiniCat 51 vs. RedCat 51: Focal Ratio and Focuser Design\u003c\/h3\u003e\n\u003cp\u003eWhile both astrographs share a 51mm aperture, the MiniCat 51 is a distinct instrument from its sibling, the RedCat 51. The choice between them depends on your specific imaging goals.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eRedCat 51 Advantage:\u003c\/strong\u003e The RedCat 51's 250mm focal length (f\/4.9) provides slightly more image scale for smaller deep-sky objects. Its helical focuser is simple and robust for manual focusing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMiniCat 51 Advantage:\u003c\/strong\u003e The MiniCat 51 is significantly faster at f\/3.5 and offers a wider 178mm focal length, making it superior for capturing enormous nebulae and multi-panel mosaics. Its WIFD rack-and-pinion focuser is built from the ground up for EAF automation and heavier camera loads, eliminating the image shift that can occur with helical focusers during autofocus routines.\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\"\u003eDoes the William Optics MiniCat 51 require a field flattener?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, it does not. The \u003cstrong\u003e6-element Petzval optical design\u003c\/strong\u003e provides a natively flat field across its 43.2mm image circle. This simplifies your imaging train and ensures sharp stars edge-to-edge with full-frame cameras without any additional accessories.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the back spacing of the MiniCat 51 WIFD?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe MiniCat 51 has a flexible back spacing range from \u003cstrong\u003e58mm to 30mm\u003c\/strong\u003e from the M48 thread. This provides ample room to accommodate various accessories like filter drawers, off-axis guiders, and different camera sensor depths while achieving perfect focus.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan the MiniCat 51 be used on a portable star tracker?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. With an OTA weight of just \u003cstrong\u003e1.67 kg (3.68 lbs)\u003c\/strong\u003e, the MiniCat 51 is an ideal payload for most portable star trackers and small equatorial mounts. Its light weight and compact 210mm tube length make it a perfect choice for a grab-and-go wide-field imaging setup.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow would the MiniCat 51 frame a large target like the Rho Ophiuchi cloud complex?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe MiniCat 51's \u003cstrong\u003e178mm focal length\u003c\/strong\u003e is perfectly suited for immense targets like Rho Ophiuchi or the Orion Nebula (M42) region. Paired with a full-frame camera, you can capture the entire complex, including the colorful nebulosity around Antares, in a single frame, a task impossible for longer focal length telescopes.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the WIFD focuser on the MiniCat 51 suitable for automated focusing?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The WIFD is a rack-and-pinion focuser specifically designed to be compatible with the \u003cstrong\u003eZWO EAF\u003c\/strong\u003e and other popular electronic autofocuser systems. Unlike helical focusers, the WIFD moves the optics internally without rotation, preventing image shift and ensuring the precise, repeatable results needed for automated imaging sessions.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat cameras can I use with the MiniCat 51?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe MiniCat 51 supports a wide range of cameras, including \u003cstrong\u003eFull Frame, APS-C, and Micro Four Thirds\u003c\/strong\u003e formats. It ships with a standard M48 camera adapter, and separate T-mounts are available for Canon EF\/RF, Nikon F\/Z, Sony E, Pentax K, MFT, and Fuji X systems.\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\u003eLens Type\u003c\/td\u003e\n\u003ctd\u003e6-Element Petzval\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLens Elements\u003c\/td\u003e\n\u003ctd\u003eSuper ED Glass x2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e51 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e178 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.5\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eImage Circle\u003c\/td\u003e\n\u003ctd\u003e43.2 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003eWIFD Rack \u0026amp; Pinion Focuser (EAF Compatible)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Travel\u003c\/td\u003e\n\u003ctd\u003e0-28 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBack Spacing\u003c\/td\u003e\n\u003ctd\u003e58-30mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFlattener Required\u003c\/td\u003e\n\u003ctd\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSupported T-Mounts\u003c\/td\u003e\n\u003ctd\u003eCanon EF, RF, Nikon F, Z, Sony E, Pentax K, MFT (M4\/3), FUJI X\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSupported Camera Formats\u003c\/td\u003e\n\u003ctd\u003eFull Frame, APS-C, M4\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDovetail Type\u003c\/td\u003e\n\u003ctd\u003eVixen \u0026amp; Arca-Swiss Dual Plate\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Length\u003c\/td\u003e\n\u003ctd\u003e210 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOTA Weight\u003c\/td\u003e\n\u003ctd\u003e1.67 kg \/ 3.68 lbs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTotal Weight\u003c\/td\u003e\n\u003ctd\u003e2.29 kg \/ 5.05 lbs\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\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eMiniCat 51 Main Tube\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBahtinov Mask Focus Aid Cap\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eMounting Ring \u0026amp; Handle Bar\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDual Vixen\/Arca-Swiss Plate\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eM48 Camera Adapter\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eTilt Adjuster \u0026amp; Rotator (M54 → M48)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eAllen Key Set\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSoft Padded Carry Case\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":49149195813149,"sku":"WO-T-C-MINI-RD","price":1363.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-MiniCat-51-1.jpg?v=1726067423"},{"product_id":"william-optics-redcat-91-wifd","title":"William Optics Cat 91 WIFD","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e91mm Aperture, 448mm Focal Length (f\/4.9)\u003c\/li\u003e\n\u003cli\u003e5-Element Advanced Petzval Optical Design\u003c\/li\u003e\n\u003cli\u003e55mm Corrected Image Circle\u003c\/li\u003e\n\u003cli\u003eWIFD Rack \u0026amp; Pinion Internal Focuser\u003c\/li\u003e\n\u003cli\u003e4.72 kg Optical Tube Assembly Weight\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\u003eWilliam Optics Cat 91 WIFD\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Cat 91 WIFD integrates a 5-element Petzval optical system into a 91mm aperture to deliver a perfectly flat 55mm image circle with zero need for an additional flattener. Its fast f\/4.9 focal ratio and 448mm focal length are engineered for capturing wide-field deep-sky targets on full-frame and medium-format sensors. The entire optical tube assembly weighs only 4.72 kg, making it a portable yet powerful astrograph for demanding imagers.\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\u003e5-Element Petzval Optics: f\/4.9 Speed and 448mm Reach\u003c\/h3\u003e\n\u003cp\u003eThe Cat 91's optical core is an advanced 5-element Petzval design that corrects for field curvature internally, eliminating the complexity of calculating back focus for an external flattener. This system uses two Super ED glass elements plus ED, Lanthanum, and another specialized element to achieve apochromatic color correction, rendering stars as sharp points with no distracting chromatic aberration. The native f\/4.9 focal ratio gathers significant light, reducing your total exposure time on faint nebulae and galaxies.\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\u003e55mm Image Circle for Full-Frame and Medium-Format Sensors\u003c\/h3\u003e\n\u003cp\u003eDesigned specifically for modern large-format sensors, the Cat 91 projects a fully illuminated and corrected 55mm image circle. This comfortably covers full-frame (36x24mm) and even larger medium-format sensors without vignetting or edge-of-field distortion. The system includes M48 and M54 adapters with precise back spacing requirements of 60.8mm and 65.8mm respectively, ensuring your sensor is placed at the optimal focal plane for edge-to-edge sharpness.\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\u003eWIFD Focuser: 36mm of Precise, Internal Travel\u003c\/h3\u003e\n\u003cp\u003eFocusing is managed by the William Optics Internal Focus Design (WIFD), a robust rack-and-pinion mechanism that moves the lens assembly internally. This design prevents the camera from sagging or tilting, a common issue with heavy imaging trains on traditional focusers. With 36mm of precise travel and direct compatibility with popular electronic auto-focusers (EAF), the WIFD system maintains rigidity and focus stability throughout an imaging session.\u003c\/p\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\"\u003eDoes the William Optics Cat 91 require a separate field flattener?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, it does not. The \u003cstrong\u003eWilliam Optics Cat 91\u003c\/strong\u003e uses a 5-element Petzval optical design, which has a flattener built directly into the optical train. This provides a flat field across its entire 55mm image circle without any additional accessories.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the correct back spacing for my camera with the Cat 91?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe required back spacing for the Cat 91 depends on the adapter you use. With the included M48 adapter, the required distance from the adapter's threads to your camera sensor is \u003cstrong\u003e60.8mm\u003c\/strong\u003e. With the M54 adapter, the required distance is \u003cstrong\u003e65.8mm\u003c\/strong\u003e.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the Cat 91's f\/4.9 ratio affect imaging the Andromeda Galaxy (M31)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe fast \u003cstrong\u003ef\/4.9 focal ratio\u003c\/strong\u003e allows the Cat 91 to collect light very efficiently. When imaging a large, relatively bright target like the Andromeda Galaxy (M31), this means you can capture significant detail in its spiral arms and faint dust lanes with shorter individual sub-exposures compared to a slower f\/6 or f\/7 refractor.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the William Optics Cat 91 compatible with my ZWO EAF?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, the WIFD (William Optics Internal Focus Design) focuser on the Cat 91 is fully compatible with ZWO EAF and other popular electronic autofocuser systems. This allows for precise, automated focusing for astrophotography.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use a full-frame DSLR camera with the Cat 91?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. The Cat 91's \u003cstrong\u003e55mm image circle\u003c\/strong\u003e is designed to fully illuminate full-frame sensors (typically 43mm diagonal) with no vignetting. You will need the appropriate T-mount adapter for your camera brand (e.g., Canon EF, Nikon F), which connects to the included M48 or M54 camera adapters.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat kind of mount is needed for the 4.72 kg Cat 91 OTA?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWith an OTA weight of \u003cstrong\u003e4.72 kg (10.41 lbs)\u003c\/strong\u003e, and a total weight with accessories around 6.3 kg, the Cat 91 works well on mid-range equatorial mounts. For imaging, a mount with a payload capacity of at least 25-30 lbs (11-14 kg) is recommended to ensure stability once you add a guide scope, cameras, and other accessories.\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\u003eLens Type\u003c\/td\u003e\n\u003ctd\u003e5-Element Advanced Petzval\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLens Elements\u003c\/td\u003e\n\u003ctd\u003eSuper ED Glass x2, ED Glass x1, Lanthanum Glass x1, X-Element x1\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e91 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e448 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/4.9\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eImage Circle\u003c\/td\u003e\n\u003ctd\u003e55 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003eWIFD R\u0026amp;P Focuser, EAF Compatible\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Travel\u003c\/td\u003e\n\u003ctd\u003e0-36 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBack Spacing (M48)\u003c\/td\u003e\n\u003ctd\u003e60.8 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBack Spacing (M54)\u003c\/td\u003e\n\u003ctd\u003e65.8 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFlattener Required\u003c\/td\u003e\n\u003ctd\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSupported Camera Formats\u003c\/td\u003e\n\u003ctd\u003eMedium Format, Full Frame, APS-C, M4\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eT-Mount Support\u003c\/td\u003e\n\u003ctd\u003eCanon EF\/RF, Nikon F\/Z, Sony E, Pentax K, MFT, FUJI X\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDovetail\u003c\/td\u003e\n\u003ctd\u003eVixen-style\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Length\u003c\/td\u003e\n\u003ctd\u003e556 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOTA Weight\u003c\/td\u003e\n\u003ctd\u003e4.72 kg \/ 10.41 lbs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTotal Weight\u003c\/td\u003e\n\u003ctd\u003e6.3 kg \/ 13.89 lbs\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\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eCat 91 Main Tube\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBahtinov Mask Lens Cap\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eMounting Ring \u0026amp; Handle Bar\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eVixen-style Dovetail Plate\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eM63 to M54 Adapter\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eM63 to M48 Adapter\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eTilt Adjuster \u0026amp; Rotator\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eRiser Blocks\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1 set\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eAllen Key Set\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSoft Carry Case\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Black","offer_id":49399187898653,"sku":"WO-T-C-91","price":4137.0,"currency_code":"CAD","in_stock":true},{"title":"Red","offer_id":49399187931421,"sku":"WO-T-C-91-RD","price":3741.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Cat-91-WIFD-pers-1.jpg?v=1732304628"},{"product_id":"william-optics-ultracat-108-f-4-8-wifd","title":"William Optics UltraCat 108 f\/4.8 WIFD","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e108mm Aperture, 5-Element Advanced Petzval Optical Design\u003c\/li\u003e\n\u003cli\u003eFast f\/4.8 Focal Ratio with 518mm Focal Length\u003c\/li\u003e\n\u003cli\u003eMassive 60mm Flat-Field Image Circle\u003c\/li\u003e\n\u003cli\u003ePatented William Optics Internal Focuser Design (WIFD)\u003c\/li\u003e\n\u003cli\u003eSupports Medium Format, Full Frame, and APS-C Sensors\u003c\/li\u003e\n\u003cli\u003e7.96 kg Optical Tube Assembly Weight\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\u003eWilliam Optics UltraCat 108 f\/4.8 WIFD\u003c\/h2\u003e\n\u003cp\u003eThe William Optics UltraCat 108 f\/4.8 WIFD integrates a 108mm, 5-element Petzval optical system to deliver a massive 60mm flat image circle at a fast f\/4.8 focal ratio. With a 518mm focal length and an OTA weight of just 7.96 kg, this astrograph is engineered for demanding imagers using full-frame and medium format cameras. The innovative internal focuser provides 30mm of precise travel, ensuring perfect focus without altering the telescope's 512.9mm minimum tube length or balance.\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\u003e5-Element Petzval Optics: A Flat 60mm Image Circle at f\/4.8\u003c\/h3\u003e\n\u003cp\u003eThe UltraCat 108's optical core is an advanced 5-element Petzval design that requires no additional field flattener. This integrated system uses a combination of two Super ED, one ED, one Lanthanum, and one X-Element glass to produce a perfectly flat 60mm image circle, ensuring pinpoint stars from the center to the corners of even medium-format sensors. At f\/4.8, you can capture deep signal on faint nebulae and galaxies with shorter exposure times.\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\u003ePatented WIFD Focuser: 30mm of Stable, Internal Travel\u003c\/h3\u003e\n\u003cp\u003eWilliam Optics' patented Internal Focuser Design (WIFD) eliminates the primary weakness of traditional refractors: focuser sag and balance shift. By moving the optical elements internally over a 30mm travel distance, the camera and imaging train remain fixed. This rock-solid connection prevents tilt and flexure, maintaining perfect orthogonality to the image plane, which is critical for achieving sharpness across the large 60mm field. The focuser is also compatible with electronic focusers like the ZWO EAF for automated imaging routines.\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\u003e7.96 kg OTA with Integrated Rotator and Tilt Adjuster\u003c\/h3\u003e\n\u003cp\u003eWeighing only 7.96 kg, the UltraCat 108 OTA is remarkably portable for its aperture and capabilities, making it compatible with a wide range of mid-to-heavy-payload equatorial mounts. The system includes professional-grade tools for perfect camera alignment right out of the box. An integrated camera rotator allows for effortless framing of your target, while the included Sensor Tilt Xterminator gives you fine control to eliminate any residual tilt in your imaging train.\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\u003eM48, M54, and M68 Adapters for Medium Format to M4\/3 Sensors\u003c\/h3\u003e\n\u003cp\u003eThe UltraCat 108 is designed for immediate integration into your existing setup. It ships with a comprehensive set of M48, M54, and M68 camera adapters, accommodating everything from standard 2\" filter wheels to large-format cameras. This ensures a wide, unvignetted light path to capitalize on the full 60mm image circle. The system also supports a wide range of T-mounts for Canon, Nikon, Sony, Pentax, MFT, and Fuji cameras, offering versatility for both dedicated astro cameras and DSLRs\/mirrorless bodies.\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\u003eUltraCat 108 vs. Takahashi FSQ-106EDX4: Aperture and Inclusions\u003c\/h3\u003e\n\u003cp\u003eThe Takahashi FSQ-106EDX4 is an industry benchmark, known for its impeccable optical quality and the ability to achieve a massive 88mm image circle with its dedicated reducer. It sets a high standard for flat-field performance.\u003c\/p\u003e\n\u003cp\u003eThe William Optics UltraCat 108 presents a compelling alternative focused on aperture and out-of-the-box functionality. It offers a larger 108mm aperture and a slightly faster native f\/4.8 focal ratio. Crucially, the UltraCat 108 includes a rotator, tilt adapter, multiple camera adapters, mounting rings, and a carrying case as standard, components that are often costly add-ons for other premium systems. This makes the UltraCat 108 a complete, ready-to-image package for the advanced astrophotographer seeking exceptional value and capability.\u003c\/p\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\"\u003eDoes the William Optics UltraCat 108 require a field flattener?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. The UltraCat 108 uses a 5-element Petzval optical design, which has a built-in field flattener. It is engineered to deliver a flat 60mm image circle with no additional optical correctors required.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the advantage of the WIFD focuser on the UltraCat 108?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe William Optics Internal Focuser Design (WIFD) moves optical elements internally to achieve focus, rather than moving the camera externally. This offers two key advantages:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eNo Sag or Flexure:\u003c\/strong\u003e Your camera and filter wheel are attached to a solid, fixed point, eliminating sag that can cause tilted images.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStable Balance:\u003c\/strong\u003e Since the heavy imaging payload doesn't move, the telescope's balance on the mount remains constant throughout the 30mm of focus travel.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the UltraCat 108's 60mm image circle benefit imaging the Andromeda Galaxy (M31) with a full-frame camera?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA full-frame sensor has a diagonal of approximately 43mm. The UltraCat 108's massive 60mm image circle completely illuminates this sensor with high-quality, pinpoint stars from edge to edge. When imaging a large target like the Andromeda Galaxy (M31), this ensures you can capture its full expanse and surrounding dust lanes without vignetting or distorted stars in the corners of your frame.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat do I need to attach my ZWO camera with a filter wheel to the UltraCat 108?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe UltraCat 108 comes with M48, M54, and M68 adapters, making it ready for most standard ZWO camera and filter wheel combinations. You will use the appropriate adapter to connect to your filter wheel, ensuring you maintain the correct back focus for a flat field. The included Sensor Tilt Xterminator allows you to make fine adjustments for perfect sensor alignment.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the 7.96 kg OTA weight of the UltraCat 108 suitable for a mount like the Sky-Watcher EQ6-R Pro?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The Sky-Watcher EQ6-R Pro typically has a payload capacity of around 20 kg (44 lbs). The UltraCat 108's total weight with rings and dovetail is 9.58 kg (21.12 lbs). Even after adding a guide scope, camera, and other accessories, the total weight will remain well within the imaging payload limit of an EQ6-R Pro or similar class mount, ensuring stable and accurate tracking.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat are the included M48, M54, and M68 adapters for?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThese are different-sized threaded adapters to connect various cameras and accessories. \u003cstrong\u003eM48\u003c\/strong\u003e is the most common standard for 2\" filters and full-frame camera connections. \u003cstrong\u003eM54\u003c\/strong\u003e and \u003cstrong\u003eM68\u003c\/strong\u003e are larger-diameter threads used on many large-format astronomy cameras and accessories to prevent vignetting and provide a more secure connection for heavy imaging trains.\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\u003eLens Type\u003c\/td\u003e\n\u003ctd\u003e5-Element Advanced Petzval\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Elements\u003c\/td\u003e\n\u003ctd\u003e5 elements including 2x Super ED, 1x ED, 1x Lanthanum, and 1x X-Element glass\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e108 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e518 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/4.8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eImage Circle\u003c\/td\u003e\n\u003ctd\u003e60 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003eWIFD Rack \u0026amp; Pinion Focuser\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Compatibility\u003c\/td\u003e\n\u003ctd\u003eCompatible with ZWO EAF\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Travel\u003c\/td\u003e\n\u003ctd\u003e30 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eField Flattener\u003c\/td\u003e\n\u003ctd\u003eNot Required\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCamera Format Support\u003c\/td\u003e\n\u003ctd\u003eMedium Format, Full Frame, APS-C, M4\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eT-Mount Support\u003c\/td\u003e\n\u003ctd\u003eCanon EF, RF; Nikon F, Z; Sony E; Pentax K; MFT (M4\/3); FUJI X\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDovetail Type\u003c\/td\u003e\n\u003ctd\u003eLosmandy-style\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Length\u003c\/td\u003e\n\u003ctd\u003e512.9 mm - 617.9 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOTA Weight\u003c\/td\u003e\n\u003ctd\u003e7.96 kg (17.55 lbs)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTotal Weight\u003c\/td\u003e\n\u003ctd\u003e9.58 kg (21.12 lbs)\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\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eUltraCat 108 Main Tube\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBahtinov Focusing Mask Cap\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eMounting Rings \u0026amp; Handlebar\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSensor Tilt Xterminator \u0026amp; Rotator\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eM68, M54, M48 Camera Adapters\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eVixen-style Plate\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSoft Carry Case\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eAllen Key Set\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":50180567367965,"sku":"WO-T-C-108BR","price":5517.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-UltraCat-108-1.jpg?v=1753236705"},{"product_id":"william-optics-ultracat-56-f-4-8-wifd","title":"William Optics UltraCat 56 f\/4.8 WIFD","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e56mm Aperture, 269mm Focal Length (f\/4.8)\u003c\/li\u003e\n\u003cli\u003e5-Element Advanced Petzval Optical Design\u003c\/li\u003e\n\u003cli\u003e50mm Image Circle for Full-Frame Sensors\u003c\/li\u003e\n\u003cli\u003eWilliam Optics Internal Focus Design (WIFD)\u003c\/li\u003e\n\u003cli\u003eWeighs only 2.56 kg (5.64 lbs)\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\u003eWilliam Optics UltraCat 56 f\/4.8 WIFD Astrograph\u003c\/h2\u003e\n\u003cp\u003eThe William Optics UltraCat 56 f\/4.8 WIFD integrates a 56mm aperture with a fast f\/4.8 focal ratio into a sophisticated 5-element Petzval design for portable wide-field imaging. Its 269mm focal length produces a massive 50mm image circle, fully illuminating full-frame sensors with perfectly flat fields and no additional flattener required. Weighing just 2.56 kg, this compact astrograph offers 0-30mm of precise internal focus travel, making it a definitive choice for capturing vast nebulae and stellar fields.\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\u003e5-Element Petzval Optics: A Flat 50mm Image Circle at f\/4.8\u003c\/h3\u003e\n\u003cp\u003eThe UltraCat 56's optical system is engineered to deliver a perfectly flat field across its entire 50mm image circle, eliminating the need for a separate field flattener. This 5-element Petzval design incorporates two Super ED glass elements, one ED element, and one Lanthanum element to achieve apochromatic color correction, rendering stars as sharp points with no distracting chromatic aberration.\u003c\/p\u003e\n\u003cp\u003eThe fast f\/4.8 focal ratio significantly reduces exposure times, allowing you to gather more signal on faint, expansive targets like the Andromeda Galaxy (M31) or the Rho Ophiuchi cloud complex in a single session. This combination of a wide, flat field and fast optics makes the UltraCat 56 an ideal instrument for full-frame and APS-C DSLR or dedicated astronomy cameras.\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\u003eWIFD Focuser: 30mm of Travel with Integrated Rotation \u0026amp; Tilt\u003c\/h3\u003e\n\u003cp\u003eAt the heart of the imaging train is the William Optics Internal Focus Design (WIFD), a robust rack-and-pinion mechanism that moves the lens elements internally. This design provides 30mm of precise focus travel without any external tube extension, preventing focuser sag and maintaining perfect balance, which is critical when using an electronic autofocuser (EAF).\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eIntegrated Rotator:\u003c\/strong\u003e The included 360° rotator allows for effortless camera framing without loosening any threaded connections, preserving optical alignment.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSensor Tilt Adjuster:\u003c\/strong\u003e A built-in tilt adapter lets you fine-tune your camera's sensor plane to be perfectly orthogonal to the optical axis, ensuring sharp stars across the entire frame.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBahtinov Mask Cap:\u003c\/strong\u003e The lens cap features an integrated Bahtinov mask, providing a simple and highly accurate tool for achieving critical focus every time.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e2.56 kg Portability with Vixen\/Arca-Swiss Compatibility\u003c\/h3\u003e\n\u003cp\u003eEngineered for imagers on the go, the UltraCat 56 OTA weighs only 2.56 kg (5.64 lbs). This low weight makes it an excellent match for portable tracking mounts and simplifies setup and transport for field use. The entire package, including rings and dovetail, comes in at a mere 3.21 kg.\u003c\/p\u003e\n\u003cp\u003eThe instrument includes a dual-function dovetail plate that is compatible with both traditional Vixen-style saddles and modern Arca-Swiss tripod heads, offering maximum mounting flexibility. The patented William Optics handle bar not only provides a secure grip but also serves as a mounting point for guide scopes or other accessories, while the included soft carry case protects the telescope during travel and storage.\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\u003eUltraCat 56 vs. RedCat 51: Aperture and Image Circle\u003c\/h3\u003e\n\u003cp\u003eWhile the RedCat 51 has established itself as a benchmark for ultra-portable astrographs, the UltraCat 56 offers key advantages for imagers seeking more light-gathering power and wider field coverage.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eRedCat 51 Advantage:\u003c\/strong\u003e The RedCat 51 is slightly smaller, lighter, and has a proven track record as one of the most popular portable imaging refractors available.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUltraCat 56 Advantage:\u003c\/strong\u003e The UltraCat 56 features a larger 56mm aperture compared to the RedCat's 51mm, providing a 20% increase in light-gathering area. Its 50mm image circle is also significantly larger than the RedCat's 44mm circle, offering superior illumination and less vignetting for full-frame and larger sensors.\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\"\u003eWhat makes the William Optics UltraCat 56's Petzval design special?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e5-element Petzval design\u003c\/strong\u003e has a field-correcting lens group built directly into the optical tube. This means you get a perfectly flat field, sharp to the edge, without needing to purchase, space, or configure a separate field flattener. It simplifies your imaging train and guarantees optimal performance out of the box.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the UltraCat 56 WIFD focuser compatible with a ZWO EAF?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, the William Optics Internal Focus Design (WIFD) focuser is fully compatible with the ZWO Electronic Automatic Focuser (EAF) and other popular EAF systems. The internal focusing mechanism prevents sag and maintains balance, making it an ideal platform for automated focusing routines.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the UltraCat 56 perform on the North America Nebula (NGC 7000) with a full-frame camera?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe UltraCat 56 is perfectly suited for this target. Its 269mm focal length and 50mm image circle will allow a full-frame sensor to capture the entire North America Nebula and the adjacent Pelican Nebula (IC 5070) in a single frame with excellent, pinpoint stars across the field. The fast f\/4.8 ratio will also help capture the faint hydrogen-alpha emissions with shorter sub-exposures.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the UltraCat 56 on a lightweight star tracker?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. With a total weight of only \u003cstrong\u003e3.21 kg (7.08 lbs)\u003c\/strong\u003e including the ring and dovetail, the UltraCat 56 is well within the capacity of most premium portable star trackers like the Sky-Watcher Star Adventurer GTi or iOptron SkyGuider Pro. Its compact size and internal focusing make it a very stable and manageable load.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the purpose of the included Sensor Tilt Xterminator on the UltraCat 56?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Sensor Tilt Xterminator is a built-in tilt adjuster. It allows you to make micro-adjustments to the angle of your camera sensor relative to the telescope's focal plane. This is used to correct for any slight sensor tilt in your camera, ensuring that you can achieve perfectly sharp, round stars in all four corners of your image.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat do I need to connect my Canon RF-mount camera to the UltraCat 56?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe UltraCat 56 includes M48 and M54 camera adapters. To connect a specific camera brand, you will need a separate, camera-specific M48 or M54 T-ring. For a Canon RF-mount camera, you would need an M48-to-Canon-RF adapter, which is widely available.\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\u003eLens Type\u003c\/td\u003e\n\u003ctd\u003e5-Element Advanced Petzval\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLens Elements\u003c\/td\u003e\n\u003ctd\u003eSuper ED Glass x2, ED Glass x1, Lanthanum Glass x1, X-Element x1\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e56 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e269 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/4.8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eImage Circle\u003c\/td\u003e\n\u003ctd\u003e50 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003eWIFD Rack \u0026amp; Pinion Focuser (EAF Compatible)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Travel\u003c\/td\u003e\n\u003ctd\u003e0-30 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFlattener Requirement\u003c\/td\u003e\n\u003ctd\u003eNo Flattener Required\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCamera Format Support\u003c\/td\u003e\n\u003ctd\u003eFull Frame, APS-C, M4\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eT-Mount Camera Support\u003c\/td\u003e\n\u003ctd\u003eCanon EF, RF, Nikon F, Z, Sony E, Pentax K, MFT (M4\/3), FUJI X\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDovetail Type\u003c\/td\u003e\n\u003ctd\u003eVixen \/ Arca-Swiss Dual Plate\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Length\u003c\/td\u003e\n\u003ctd\u003e296.3 mm - 348.3 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOTA Weight\u003c\/td\u003e\n\u003ctd\u003e2.56 kg (5.64 lbs)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTotal Weight\u003c\/td\u003e\n\u003ctd\u003e3.21 kg (7.08 lbs)\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\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eUltraCat 56 Main Tube\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBahtinov Mask Cap\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eMounting Ring \u0026amp; Handle Bar\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDual-side Vixen\/Arca-Swiss Plate\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSensor Tilt Xterminator Rotator\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eM54 \u0026amp; M48 Camera Adapters\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eAdapter Wrench\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eAllen Key Set\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSoft Carry Case\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":50846087184669,"sku":"WO-T-C-56BR","price":1929.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-UltraCat-56-WIFD-1.jpg?v=1768578664"},{"product_id":"william-optics-ultracat-76-f-4-8-wifd","title":"William Optics UltraCat 76 f\/4.8 WIFD","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e76 mm Aperture, 365 mm Focal Length (f\/4.8)\u003c\/li\u003e\n\u003cli\u003e5-Element Advanced Petzval Optical Design\u003c\/li\u003e\n\u003cli\u003e50 mm Corrected Image Circle\u003c\/li\u003e\n\u003cli\u003eWilliam Optics Internal Focusing Design (WIFD)\u003c\/li\u003e\n\u003cli\u003eTotal Weight of 4.98 kg (10.98 lbs)\u003c\/li\u003e\n\u003cli\u003eDual Vixen\/Arca-Swiss Dovetail Plate\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\u003eWilliam Optics UltraCat 76 f\/4.8 WIFD\u003c\/h2\u003e\n\u003cp\u003eThe William Optics UltraCat 76 f\/4.8 WIFD integrates a 5-element Petzval optical system into a portable 76 mm aperture refractor, delivering a perfectly flat 50 mm image circle without an external flattener. Its fast f\/4.8 focal ratio and 365 mm focal length are engineered for wide-field deep-sky imaging, capturing immense targets on full-frame sensors. The entire imaging package, weighing only 4.98 kg, is built around an internal focuser design to eliminate sag and maintain perfect balance.\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\u003e5-Element Petzval Optics: A 50mm Flat Field with No Flattener\u003c\/h3\u003e\n\u003cp\u003eThe core of the UltraCat 76 is its advanced 5-element Petzval lens system, which uses two Super ED, one ED, and one Lanthanum glass element to achieve outstanding apochromatic color correction. This design naturally corrects for field curvature, producing pinpoint stars across a massive 50 mm image circle, fully illuminating full-frame and even larger sensors without vignetting. By eliminating the need for a separate flattener, your imaging train is simpler, lighter, and more rigid.\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\u003eWIFD Focuser: 20mm Internal Travel with Integrated Tilt Control\u003c\/h3\u003e\n\u003cp\u003eWilliam Optics' patented Internal Focusing Design (WIFD) moves the optical assembly internally, preventing the drawtube sag and balance shift common with external focusers. With 20 mm of precise travel, the rack-and-pinion mechanism is compatible with EAF systems for automated focusing. The entire focuser assembly includes a camera rotator for framing, M48 and M54 adapters, and the Sensor Tilt Xterminator, giving you complete control over your imaging train for perfectly flat and sharp fields.\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\u003eEngineered for Portability: 4.98 kg Total Weight and Vixen\/Arca-Swiss Plate\u003c\/h3\u003e\n\u003cp\u003eDesigned for field use, the UltraCat 76 has a total weight of just 4.98 kg (10.98 lbs) with rings and dovetail attached. This makes it an ideal match for modern portable equatorial mounts. The included dual-side dovetail plate offers native Vixen and Arca-Swiss compatibility, allowing you to mount it on virtually any astronomical or photographic tripod head without extra hardware. The package includes a patented handle bar, riser blocks for optimal balancing, and a soft carry case for transport and storage.\u003c\/p\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\"\u003eWhy doesn't the William Optics UltraCat 76 need a field flattener?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe UltraCat 76 uses a \u003cstrong\u003e5-element Petzval optical design\u003c\/strong\u003e. This advanced configuration has corrective elements built into the rear of the optical tube, which naturally corrects for field curvature. This provides a flat 50 mm image circle without the need for an external flattener, simplifying your setup.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the UltraCat 76's 50mm image circle perform with a full-frame camera on the North American Nebula (NGC 7000)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe 50 mm image circle is significantly larger than a standard full-frame sensor (43mm diagonal), ensuring the entire sensor is fully illuminated with no vignetting. Paired with the 365 mm focal length, you can easily capture the entire North American Nebula (NGC 7000) and the adjacent Pelican Nebula (IC 5070) in a single, sharp, flat frame.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the UltraCat 76's WIFD focuser compatible with a ZWO EAF?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, the William Optics Internal Focusing Design (WIFD) is fully compatible with the ZWO EAF and other popular electronic automatic focusers. The internal rack-and-pinion mechanism provides the stability and precision required for automated focusing routines.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the advantage of the UltraCat 76's internal focuser design?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe WIFD moves the optics internally rather than extending a drawtube. This offers two key advantages:\n\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eNo Sag:\u003c\/strong\u003e It eliminates the potential for drawtube sag, which can cause image tilt with heavy camera setups.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStable Balance:\u003c\/strong\u003e Since the overall length of the telescope doesn't change during focusing, the center of balance remains constant, preventing tracking issues.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I use the Sensor Tilt Xterminator included with the UltraCat 76?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe included Sensor Tilt Xterminator is a tilt adapter that sits in the imaging train. It has adjustment screws that allow you to make minute changes to the camera sensor's angle relative to the optical axis. This lets you correct for any sensor tilt, ensuring perfectly sharp stars from corner to corner of your image.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat camera mounts are supported by the UltraCat 76?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe UltraCat 76 includes M48 and M54 camera adapters, and supports a wide range of T-mounts for direct connection to popular DSLR and mirrorless cameras. Supported systems include \u003cstrong\u003eCanon EF, RF, Nikon F, Z, Sony E, Pentax K, MFT (M4\/3), and FUJI X\u003c\/strong\u003e.\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\u003eLens Type\u003c\/td\u003e\n\u003ctd\u003e5-Element Advanced Petzval\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLens Elements\u003c\/td\u003e\n\u003ctd\u003eSuper ED Glass x2, ED Glass x1, Lanthanum Glass x1, X-Element x1\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e76 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e365 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/4.8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eImage Circle\u003c\/td\u003e\n\u003ctd\u003e50 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003eWIFD Rack \u0026amp; Pinion Focuser\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Compatibility\u003c\/td\u003e\n\u003ctd\u003eEAF Compatible\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Travel\u003c\/td\u003e\n\u003ctd\u003e0-20 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFlattener Requirement\u003c\/td\u003e\n\u003ctd\u003eNo Flattener Required\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCamera Format Support\u003c\/td\u003e\n\u003ctd\u003eFull Frame, APS-C, M4\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eT-Mount Support\u003c\/td\u003e\n\u003ctd\u003eCanon EF, RF; Nikon F, Z; Sony E; Pentax K; MFT (M4\/3); FUJI X\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDovetail Type\u003c\/td\u003e\n\u003ctd\u003eVixen \/ Arca-Swiss Dual Plate\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Length\u003c\/td\u003e\n\u003ctd\u003e363 mm - 415 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOTA Weight\u003c\/td\u003e\n\u003ctd\u003e3.81 kg \/ 8.4 lbs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTotal Weight\u003c\/td\u003e\n\u003ctd\u003e4.98 kg \/ 10.98 lbs\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\u003cli class=\"DAV-grid-item\"\u003e\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eUltraCat 76 Main Tube\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBahtinov Cap\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eMounting Ring \u0026amp; Handle bar\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDual-side Vixen\/Arca-Swiss Plate\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eRiser Blocks\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSensor Tilt Xterminator Rotator\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eM54 \u0026amp; M48 Camera Adapters\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eM48, M54 Adapter Wrench\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eAllen Key Set\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSoft Carry Case\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":50846093934877,"sku":"WO-T-C-76BR","price":3033.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-UltraCat-76-WIFD-1.jpg?v=1768578903"},{"product_id":"william-optics-t-c-131br","title":"William Optics Ultra-Cat 131 f\/4.9 Petzval Astrograph","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e131mm Aperture\u003c\/li\u003e\n\u003cli\u003e648mm Focal Length (f\/4.9)\u003c\/li\u003e\n\u003cli\u003e5-Element Advanced Petzval Optical Design\u003c\/li\u003e\n\u003cli\u003e60mm Flat-Field Image Circle\u003c\/li\u003e\n\u003cli\u003ePatented WIFD Internal Focuser\u003c\/li\u003e\n\u003cli\u003e13.97 kg Total Weight\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\u003eWilliam Optics Ultra-Cat 131 f\/4.9 Petzval Astrograph\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Ultra-Cat 131 combines a massive 131mm aperture with a fast f\/4.9 focal ratio, delivering exceptional light-gathering power for serious deep-sky imagers. Its 5-element Petzval optical system produces a completely flat 60mm image circle without an external flattener, fully illuminating medium-format sensors. With a native 648mm focal length and a total weight of 13.97 kg, this astrograph is engineered for capturing vast, high-resolution celestial portraits with pinpoint stars from edge to edge.\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\u003eFlagship 131mm Petzval Optics: A 60mm Flat-Field Image Circle\u003c\/h3\u003e\n\u003cp\u003eThe optical core of the Ultra-Cat 131 is an advanced 5-element Petzval design featuring two Super ED elements, one ED element, and one Lanthanum element. This sophisticated configuration eliminates the need for a separate field flattener, correcting for field curvature and chromatic aberration natively to produce a perfectly flat 60mm image circle. This allows you to place your medium-format or full-frame sensor anywhere within the field and achieve sharp, perfectly formed stars.\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\u003ePatented WIFD Focuser: 20mm of Zero-Shift Internal Focus\u003c\/h3\u003e\n\u003cp\u003eWilliam Optics' patented WIFD (William Optics Internal Focuser Design) provides 20mm of precise focus travel without any external drawtube movement. By moving the optics internally, the system completely avoids the balance shifts, flexure, and vignetting common with traditional focusers. This robust design maintains perfect optical alignment and rigidity, even when loaded with heavy imaging trains, and is fully compatible with electronic auto-focusers (EAF).\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\u003eObservatory-Grade Build: 13.97 kg of Stability and Broad Camera Support\u003c\/h3\u003e\n\u003cp\u003eEngineered for thermal stability and mechanical rigidity, the Ultra-Cat 131 weighs in at a substantial 13.97 kg with all accessories. It ships with robust mounting rings and a Losmandy-style dovetail plate for secure attachment to observatory-class mounts. The package includes a comprehensive set of M68, M54, and M48 camera adapters and a Sensor Tilt Xterminator (STX-R), ensuring you can achieve perfect sensor alignment with virtually any Canon, Nikon, Sony, or dedicated astronomy camera.\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\u003eUltra-Cat 131 vs. 106mm Refractors: The Aperture Advantage\u003c\/h3\u003e\n\u003cp\u003eWhen compared to premium 106mm refractors, the Ultra-Cat 131's primary advantage is its sheer light-gathering power and field coverage. The difference in aperture provides a significant boost in signal for faint deep-sky targets.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eLight Gathering:\u003c\/strong\u003e The 131mm objective collects over 50% more light than a 106mm objective, allowing you to capture fainter details in the same exposure time or significantly shorten your sub-exposures.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImage Circle:\u003c\/strong\u003e The Ultra-Cat's native 60mm flat image circle dwarfs the 44mm circle typical of full-frame-corrected 106mm scopes, providing superior illumination and vignetting control for large sensors.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIntegrated Design:\u003c\/strong\u003e While many refractors require a separate, carefully spaced flattener, the Ultra-Cat 131's Petzval design is inherently corrected, simplifying your imaging train and eliminating a potential source of tilt and error.\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 does the Ultra-Cat 131's 60mm image circle benefit imaging the Andromeda Galaxy (M31) with a full-frame camera?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Andromeda Galaxy is a massive target. The Ultra-Cat 131's 648mm focal length and 60mm image circle allow you to frame the entire galaxy, including its faint outer arms and satellite galaxies M32 and M110, on a full-frame sensor with excellent illumination and sharp stars right to the corners of the frame. A smaller image circle would introduce significant vignetting, darkening the edges and losing crucial detail.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat class of mount is required for the 13.97 kg total weight of the Ultra-Cat 131?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWith a total weight of 13.97 kg (30.8 lbs), plus the weight of your camera, guide scope, and other accessories, you will need a robust equatorial mount with a payload capacity of at least 50-60 lbs (22-27 kg) for reliable astrophotography. Mounts in the Sky-Watcher EQ6-R Pro, iOptron CEM60\/70, or Losmandy G11 class are recommended for stable, long-exposure imaging with the Ultra-Cat 131.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDo I need a separate field flattener for the Ultra-Cat 131?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. The Ultra-Cat 131 uses an advanced 5-element Petzval optical design that has field flattening built-in. It produces a perfectly flat 60mm image circle without the need for any additional flattener or reducer, simplifying your imaging train.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the WIFD internal focuser on the Ultra-Cat 131 improve imaging sessions?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe WIFD (William Optics Internal Focuser Design) offers two key advantages. First, because only internal optical elements move, the overall length of the telescope never changes. This keeps the balance point constant, preventing tracking errors as you cross the meridian. Second, it eliminates drawtube sag, a common problem with heavy cameras on traditional focusers, ensuring your sensor remains perfectly orthogonal to the light path.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the f\/4.9 focal ratio of the Ultra-Cat 131 fast enough for narrowband imaging of targets like the Elephant's Trunk Nebula (IC 1396)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. An f\/4.9 focal ratio is considered very fast for astrophotography. This speed allows you to collect a strong signal with narrowband filters (like H-alpha, OIII, and SII) in a fraction of the time it would take with a slower f\/7 or f\/8 system, making it ideal for capturing deep, high-contrast images of emission nebulae like IC 1396.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the purpose of the included Sensor Tilt Xterminator (STX-R) with the Ultra-Cat 131?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Sensor Tilt Xterminator (STX-R) is a precision tilt adapter. It allows you to make minute adjustments to the angle of your camera sensor relative to the telescope's optical axis. This is crucial for achieving perfectly sharp stars across a large, flat field, as it corrects for any slight tilt that may exist in your camera or focuser.\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\u003eOptical Design\u003c\/td\u003e\n\u003ctd\u003e5-Element Advanced Petzval\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLens Elements\u003c\/td\u003e\n\u003ctd\u003eSuper ED Glass x2, ED Glass x1, Lanthanum Glass x1, X-Element x1\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e131 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e648 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/4.9\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eImage Circle\u003c\/td\u003e\n\u003ctd\u003e60 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003eWIFD Rack \u0026amp; Pinion Internal Focuser, EAF Compatible\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Travel\u003c\/td\u003e\n\u003ctd\u003e0-20 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFlattener Required\u003c\/td\u003e\n\u003ctd\u003eNo\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSupported Camera Formats\u003c\/td\u003e\n\u003ctd\u003eMedium Format, Full Frame, APS-C, M4\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSupported T-Mounts\u003c\/td\u003e\n\u003ctd\u003eCanon EF, RF; Nikon F, Z; Sony E; Pentax K; MFT (M4\/3); FUJI X\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDovetail Type\u003c\/td\u003e\n\u003ctd\u003eLosmandy\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Length (Retracted\/Extended)\u003c\/td\u003e\n\u003ctd\u003e650 mm - 785.5 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOTA Weight\u003c\/td\u003e\n\u003ctd\u003e11.3 kg \/ 24.91 lbs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTotal Weight\u003c\/td\u003e\n\u003ctd\u003e13.97 kg \/ 30.8 lbs\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\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eUltra-Cat 131 Main Tube\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBahtinov Mask Focus Aid Cap\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSensor Tilt Xterminator (STX-R)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eM68, M54, and M48 Camera Adapters\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eMounting Rings \u0026amp; Handle Bar\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eLosmandy-Style Dovetail Plate\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eSoft Padded Carry Case\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eAllen Key Set \u0026amp; Wrench\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":52853689057565,"sku":"WO-T-C-131BR","price":7449.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/WilliamOptics-Ultra-Cat-131-1_4421596a-b1ce-428f-84ff-326b3a644d9a.jpg?v=1788457750"}],"url":"https:\/\/davidastro.com\/collections\/william-optics-cat-series-telescopes.oembed","provider":"David Astro","version":"1.0","type":"link"}