{"title":"William Optics Telescopes","description":"\u003cp\u003eWilliam Optics telescopes are compact refractors known for astrophotography and portable visual use. The Cat series covers Petzval designs such as the RedCat 51, 61 and 71, the MiniCat 51 and the UltraCat 56, 108 and 131, with a flat field built in.\u003c\/p\u003e\u003cp\u003eThe Pleiades 111 is a seven-element astrograph. For classic apochromats, there are the Zenithstar 61II doublet, the Gran Turismo 71 and GT81 WIFD triplets and the larger Fluorostar 120 and 156.\u003c\/p\u003e","products":[{"product_id":"william-optics-fluorostar-132","title":"William Optics Fluorostar 132","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e132mm Aperture, 910mm Focal Length (f\/6.9)\u003c\/li\u003e\n\u003cli\u003eAir-Spaced Triplet Apochromatic Objective\u003c\/li\u003e\n\u003cli\u003ePremium FPL-53 Glass for Superior Color Correction\u003c\/li\u003e\n\u003cli\u003eHeavy-Duty 3.7\" Rack \u0026amp; Pinion Focuser\u003c\/li\u003e\n\u003cli\u003e360° Rotatable Focuser for Easy Framing\u003c\/li\u003e\n\u003cli\u003eFully CNC-Machined Aluminum Tube\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 Fluorostar 132 APO Refractor\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Fluorostar 132 combines a 132mm aperture with a 910mm focal length (f\/6.9) to serve as a premier instrument for high-resolution astrophotography and critical visual observation. Its air-spaced triplet objective lens uses premium FPL-53 glass to achieve apochromatic correction, while the massive 3.7-inch Rack \u0026amp; Pinion focuser provides zero-flexure support for full-frame imaging systems.\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\u003e132mm f\/6.9 FPL-53 Triplet: Pure Color Correction\u003c\/h3\u003e\n\u003cp\u003eAt the core of the Fluorostar 132 is a three-element objective lens featuring FPL-53 glass, the gold standard for color error correction. This apochromatic design virtually eliminates chromatic aberration, ensuring there is no spurious purple or green fringing around bright stars like Vega or on the limb of Jupiter. With high-transmission STM coatings, the FLT132 delivers exceptionally high contrast, revealing subtle planetary details and rendering stars as sharp, color-pure points against a black-sky background.\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\u003e3.7\" Rack \u0026amp; Pinion Focuser: 360° of Imaging Precision\u003c\/h3\u003e\n\u003cp\u003eDesigned for the demands of modern astrophotography, the FLT132 is equipped with a heavy-duty 3.7\" rack and pinion focuser. This large-aperture focuser can carry heavy imaging trains—including large-format cameras, filter wheels, and off-axis guiders—without sagging or flexure. For perfect composition, the entire focuser assembly rotates a full 360 degrees, allowing you to frame targets like the North American Nebula (NGC 7000) exactly as you wish without ever loosening your 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\u003eA Robust 132mm OTA with CNC-Machined Precision\u003c\/h3\u003e\n\u003cp\u003eThe optical tube is crafted from solid CNC-machined aluminum, providing a rigid and thermally stable platform essential for consistent focus through long imaging sessions. The powder-painted white tube is durable and presents a classic, clean aesthetic. Every Fluorostar 132 includes a high-quality soft carrying case, protecting your investment during transport to dark-sky sites and making this powerful 132mm refractor surprisingly manageable.\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\u003eFLT132 vs. Standard 130mm Refractors: The 3.7\" Focuser Advantage\u003c\/h3\u003e\n\u003cp\u003eWhile many refractors in the 130mm class deliver excellent optical views, the Fluorostar 132 sets itself apart with its imaging-centric design, most notably its focuser.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eTypical Refractors:\u003c\/strong\u003e Many competitors use 2.5\" or 3\" focusers, which are adequate for smaller sensors but can become a bottleneck for flexure and illumination with larger cameras.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFluorostar 132:\u003c\/strong\u003e The 3.7\" focuser provides a wider, unvignetted light path for full-frame and larger sensors, especially when paired with a compatible reducer or flattener. Its robust build quality means you can invest in a heavy imaging setup without needing to budget for an immediate focuser upgrade.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the Fluorostar 132 perform on planetary targets like Jupiter with its 910mm focal length?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003eWilliam Optics Fluorostar 132\u003c\/strong\u003e is an excellent planetary instrument. Its 910mm focal length provides ample image scale for planets, and the FPL-53 triplet optics deliver the high-contrast, color-free views needed to resolve fine details like Jupiter's Great Red Spot, cloud bands, and the Cassini Division in Saturn's rings.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the FLT132 suitable for imaging large deep-sky objects like 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\u003eYes. At its native 910mm focal length, the FLT132 will frame the core of M31 beautifully. When paired with a compatible field flattener or reducer, it provides a flat, well-corrected field for full-frame sensors. The large 3.7\" focuser is specifically designed to prevent vignetting and support the weight of a full-frame imaging setup.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat makes the FPL-53 triplet objective in the Fluorostar 132 superior to a doublet?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA \u003cstrong\u003etriplet objective\u003c\/strong\u003e with \u003cstrong\u003eFPL-53 glass\u003c\/strong\u003e corrects for chromatic aberration (false color) across a much wider spectrum than a standard doublet. This results in significantly higher contrast, sharper stars with no color fringing, and more faithful color rendition in astrophotos, which is especially critical for imaging and observing bright objects.\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 3.7\" focuser on the William Optics FLT132?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e3.7\" Rack \u0026amp; Pinion focuser\u003c\/strong\u003e offers two main advantages for astrophotography:\n\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eHigh Payload Capacity:\u003c\/strong\u003e It can hold heavy cameras, filter wheels, and other accessories without flexing or slipping, ensuring consistent focus.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull Illumination:\u003c\/strong\u003e The large diameter prevents vignetting (darkening of the corners) on large camera sensors, such as full-frame DSLRs or dedicated astronomy cameras.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat field flatteners are compatible with the FLT132?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe William Optics Fluorostar 132 is designed to be compatible with several of their high-quality field flatteners and reducers, including the \u003cstrong\u003eP-FLAT68III\u003c\/strong\u003e, \u003cstrong\u003eP-Flat7A\u003c\/strong\u003e, and \u003cstrong\u003eP-Flat8\u003c\/strong\u003e. Using one of these accessories is recommended for astrophotography to ensure pinpoint stars across the entire field of view.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes the Fluorostar 132 come with a case for transport?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, the William Optics FLT132 includes a high-quality soft carrying case. This padded case is designed to protect the telescope during storage and transport to your observing location.\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\u003e132mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e910mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/6.9\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eObjective Design\u003c\/td\u003e\n\u003ctd\u003eAir-Spaced Apochromatic Triplet\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eObjective Glass\u003c\/td\u003e\n\u003ctd\u003eFPL-53\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eSTM Coatings\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003e3.7\" Rack \u0026amp; Pinion\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Rotation\u003c\/td\u003e\n\u003ctd\u003e360 degrees\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Construction\u003c\/td\u003e\n\u003ctd\u003eCNC-machined Aluminum\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompatible Flatteners\u003c\/td\u003e\n\u003ctd\u003eP-FLAT68III, P-Flat7A, P-Flat8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAvailable Colors\u003c\/td\u003e\n\u003ctd\u003eRed, Gold, Grey\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\"\u003eFluorostar 132 Optical Tube Assembly\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 Carrying 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\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 \/ 3.3\" R\u0026P","offer_id":44967227457821,"sku":"WO-A-F132RDIII-RP33R","price":6304.0,"currency_code":"CAD","in_stock":true},{"title":"Red \/ 3.5\" Feather Touch","offer_id":44967227556125,"sku":"WO-A-F132RDIII-FTR","price":8162.0,"currency_code":"CAD","in_stock":true},{"title":"Gold \/ 3.3\" R\u0026P","offer_id":44967227425053,"sku":"WO-A-F132GDIII-RP33R","price":6304.0,"currency_code":"CAD","in_stock":true},{"title":"Gold \/ 3.5\" Feather Touch","offer_id":44967227490589,"sku":"WO-A-F132GDIII-FTR","price":8162.0,"currency_code":"CAD","in_stock":true},{"title":"Grey \/ 3.3\" R\u0026P","offer_id":48966062702877,"sku":"WO-A-F132TGIV-RP37","price":6897.0,"currency_code":"CAD","in_stock":true},{"title":"Grey \/ 3.5\" Feather Touch","offer_id":48966062735645,"sku":"WO-A-F132TGIV-FT","price":8162.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-FLT132-1.jpg?v=1722277044"},{"product_id":"william-optics-fluorostar-156","title":"William Optics Fluorostar 156","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e156mm Aperture Triplet Apochromat\u003c\/li\u003e\n\u003cli\u003e1217mm Focal Length (f\/7.8)\u003c\/li\u003e\n\u003cli\u003eFPL-53 \u0026amp; Lanthanum Glass Elements\u003c\/li\u003e\n\u003cli\u003e3.7\" Rack \u0026amp; Pinion Focuser\u003c\/li\u003e\n\u003cli\u003eThermally Stable Steel Objective Cell\u003c\/li\u003e\n\u003cli\u003eIntegrated Bahtinov Mask in Dust Cover\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 Fluorostar 156 f\/7.8 Triplet APO Refractor\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Fluorostar 156 combines a large 156mm aperture with a 1217mm (f\/7.8) focal length in a precision-engineered, air-spaced triplet optical system. Featuring premium FPL-53 glass and a Lanthanum element, this apochromatic refractor suppresses false color to undetectable levels, supported by a massive 3.7\" Rack \u0026amp; Pinion focuser for precise, no-slip focusing with heavy imaging payloads.\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 156mm f\/7.8 Triplet APO: Color-Free Views with FPL-53 Glass\u003c\/h3\u003e\n\u003cp\u003eAt the heart of the Fluorostar 156 lies an air-spaced triplet objective that sets the standard for color correction and contrast. By combining a key element of FPL-53 glass with another of Lanthanum, the optical design brings all wavelengths of visible light to a single, sharp focal point. This eliminates the distracting purple fringing seen on bright stars in lesser instruments, delivering crisp, high-contrast views of planetary details and pinpoint stars across the entire field for astrophotography.\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\u003eThermally Stable Steel Cell: Maintaining Collimation at 156mm\u003c\/h3\u003e\n\u003cp\u003eA large 156mm objective lens is susceptible to subtle shifts as ambient temperature drops, which can degrade image sharpness. William Optics addresses this with a robust steel objective cell that mitigates thermal expansion and contraction. This ensures the triplet lens elements remain in perfect alignment throughout a long imaging session, preserving the exquisite optical correction from dusk until dawn.\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\u003eImaging-Ready Mechanics: A 3.7\" Focuser and Integrated Bahtinov Mask\u003c\/h3\u003e\n\u003cp\u003eThe Fluorostar 156 is built from the ground up for serious astrophotography. The heavy-duty 3.7\" rack and pinion focuser provides a rigid, stable platform for large cameras and filter wheels, eliminating flexure and focus shift. For achieving perfect focus, the lens cap features an integrated Bahtinov mask—a critical tool for hitting sharp focus in seconds. The entire optical tube is secured by three CNC-machined rings and a standard Losmandy-style dovetail plate, creating a solid foundation for any capable equatorial mount.\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 kind of mount is required for the William Optics Fluorostar 156?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eDue to its aperture and focal length, the Fluorostar 156 is a substantial instrument. A robust equatorial mount with a payload capacity of at least 50-60 lbs (22-27 kg) or more is strongly recommended for stable imaging and visual use. Mounts in the Celestron CGX, Losmandy G11, or Software Bisque Paramount MYT class are appropriate.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the FPL-53 and Lanthanum glass in the Fluorostar 156 benefit astrophotography?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis combination of exotic glass types provides exceptional apochromatic performance. For astrophotography, this means:\n\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eNo Chromatic Aberration:\u003c\/strong\u003e Bright stars like Vega or Sirius will not have distracting blue or purple halos, resulting in cleaner, more natural-looking star fields.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHigher Contrast:\u003c\/strong\u003e By focusing all colors to the same point, fine details in nebulae and galaxies are not smeared or washed out, leading to sharper and more detailed images.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImproved Spectrographic Use:\u003c\/strong\u003e The clean color correction makes this an excellent instrument for use with narrowband filters (H-alpha, OIII, SII), as stars will be tight and round across all filtered channels.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the advantage of the integrated Bahtinov mask on the Fluorostar 156?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Bahtinov mask, integrated directly into the dust cover, is a significant convenience for astrophotographers. It creates a distinctive diffraction pattern around a bright star that instantly shows you when you have achieved perfect focus. This eliminates the guesswork of trying to find the point of sharpest focus by eye, saving valuable imaging time and ensuring your data is critically sharp every time.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Fluorostar 156 for visual observation as well as imaging?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. While optimized for imaging, the Fluorostar 156 is a superb visual instrument. Its 156mm aperture provides brilliant, high-resolution views of the Moon, planets, and deep-sky objects. The apochromatic optics deliver a pure, high-contrast image that is free of false color, making it ideal for discerning subtle cloud bands on Jupiter or resolving tight double stars.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the Fluorostar 156 perform on faint details in the Orion Nebula (M42)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Fluorostar 156's combination of 156mm aperture and high-contrast optics makes it an exceptional tool for M42. Visually, you can expect to resolve the E and F stars in the Trapezium cluster under good seeing conditions. For imaging, the 1217mm focal length perfectly frames the nebula's core while the sharp optics will capture the faint, intricate structures of the surrounding nebulosity with stunning clarity.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the 1217mm focal length of the Fluorostar 156 suitable for imaging smaller galaxies like the Whirlpool Galaxy (M51)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, the 1217mm focal length is an excellent match for medium-to-small deep-sky objects like M51, the Hercules Cluster (M13), or the Ring Nebula (M57). It provides enough image scale to resolve spiral arms, dust lanes, and individual stars in globular clusters, especially when paired with a modern astronomy camera with small pixels.\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\u003e156mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e1217mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/7.8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Design\u003c\/td\u003e\n\u003ctd\u003eAir-Spaced Triplet Apochromat\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eGlass Composition\u003c\/td\u003e\n\u003ctd\u003eFPL-53 \u0026amp; Lanthanum Elements\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003e3.7\" Rack \u0026amp; Pinion\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eObjective Cell Construction\u003c\/td\u003e\n\u003ctd\u003eSteel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAvailable Accent Colors\u003c\/td\u003e\n\u003ctd\u003eRed, Gold, Space Grey\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\"\u003eFluorostar 156 OTA\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\"\u003e3.7\" Rack \u0026amp; Pinion Focuser\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 Cover\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\"\u003eCNC Tube Rings\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 3\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 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":"Red","offer_id":44967228080413,"sku":"WO-A-F156RD-RP37","price":10653.0,"currency_code":"CAD","in_stock":true},{"title":"Gold","offer_id":44967228014877,"sku":"WO-A-F156GD-RP37","price":12417.0,"currency_code":"CAD","in_stock":true},{"title":"Grey","offer_id":44967228047645,"sku":"WO-A-F156TG-RP37","price":12417.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-FLT156-1.jpg?v=1722277379"},{"product_id":"william-optics-gran-turismo-71-apo-triplet","title":"William Optics Gran Turismo 71 APO Triplet","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e71mm Triplet Apochromatic Lens\u003c\/li\u003e\n\u003cli\u003e419mm Focal Length at f\/5.9\u003c\/li\u003e\n\u003cli\u003e44mm Full-Frame Image Circle\u003c\/li\u003e\n\u003cli\u003e2.5\" Rack \u0026amp; Pinion Focuser\u003c\/li\u003e\n\u003cli\u003eOTA Weight: 2.95 kg (6.5 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 Gran Turismo 71 APO Triplet\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Gran Turismo 71 APO Triplet combines a 71mm aperture with a 419mm focal length in a fast f\/5.9 optical design. Its triplet objective lens, featuring FPL-53 glass, delivers sharp, high-contrast images free of false color, illuminating a full-frame 44mm image circle. Weighing just 2.95 kg, the GT71 is engineered for premium wide-field astrophotography on portable, lightweight tracking mounts.\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\u003eTriplet APO Optics: 419mm at f\/5.9 with FPL-53 Glass\u003c\/h3\u003e\n\u003cp\u003eThe core of the GT71 is its air-spaced triplet apochromatic lens. This design uses an FPL-53 glass element to virtually eliminate chromatic aberration, ensuring star colors are rendered accurately and details are resolved with high contrast. The native 419mm focal length at f\/5.9 provides a versatile field of view, ideal for capturing large nebulae and star clusters while maintaining a manageable image scale for 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\u003eImaging-Ready Mechanics: 2.5\" R\u0026amp;P Focuser and 44mm Image Circle\u003c\/h3\u003e\n\u003cp\u003eBuilt for modern astrophotography, the Gran Turismo 71 is equipped with a heavy-duty 2.5\" rack-and-pinion focuser. This focuser provides 93mm of travel and can handle heavy imaging trains without slipping, while being directly compatible with electronic focusers like the ZWO EAF. The optical system is designed to produce a flat, well-illuminated 44mm image circle, fully covering full-frame sensors from edge to edge with the addition of an optional flattener.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCamera Compatibility:\u003c\/strong\u003e The 44mm image circle supports Full Frame, APS-C, and M4\/3 sensors, offering flexibility for your current and future cameras.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOptional Reducers:\u003c\/strong\u003e Choose the FLAT GT 1.0x for edge-to-edge correction at the native 419mm focal length, or the FLAT 6AIII 0.8x reducer to transform the scope into a faster f\/4.7 system for even wider fields.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCamera Angle Adjuster:\u003c\/strong\u003e A 360° camera angle adjuster is included, allowing for precise framing of your target without altering focus.\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\u003eGrab-and-Go Design: 2.95 kg with Vixen\/Arca-Swiss Dovetail\u003c\/h3\u003e\n\u003cp\u003eThe entire optical tube assembly weighs only 2.95 kg (6.5 lbs), making the GT71 an ideal choice for portable setups like the Sky-Watcher Star Adventurer or iOptron SkyGuider Pro. Its adjustable tube length, from 392mm to 470mm, allows for compact storage and travel. The integrated dovetail bar features both a Vixen-style rail for astronomy mounts and an Arca-Swiss profile for direct attachment to standard photographic tripods, adding to its field versatility.\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\"\u003eCan the William Optics GT71 be used with a full-frame camera?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The Gran Turismo 71 is designed with a \u003cstrong\u003e44mm image circle\u003c\/strong\u003e, which is large enough to fully illuminate a standard full-frame sensor (typically 43mm diagonal) without vignetting. For optimal edge-of-field star shapes, pairing it with a dedicated flattener like the FLAT GT 1.0x or the FLAT 6AIII 0.8x reducer is required.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat kind of mount do I need for the Gran Turismo 71?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWith an OTA weight of only \u003cstrong\u003e2.95 kg (6.5 lbs)\u003c\/strong\u003e, the GT71 is exceptionally versatile. It performs well on robust star trackers like the Sky-Watcher Star Adventurer GTi or small equatorial mounts in the EQ3\/EQM-35 class. For more serious imaging with autoguiding, a mount from the HEQ5\/CEM26 class is recommended.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the GT71 perform on the North American Nebula (NGC 7000) with the 0.8x reducer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe GT71 is an excellent choice for this target. With the optional \u003cstrong\u003eFLAT 6AIII 0.8x reducer\u003c\/strong\u003e, the focal length becomes approximately 335mm at f\/4.7. Paired with an APS-C sensor, this combination can easily frame the entire North American Nebula and the adjacent Pelican Nebula (IC 5070) in a single shot with high resolution.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the GT71 suitable for visual astronomy on objects like the Orion Nebula (M42)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. While optimized for imaging, the GT71's triplet APO lens provides superb, high-contrast views for visual use. On the Orion Nebula (M42), you can expect sharp, pinpoint stars across the Trapezium cluster and clear views of the surrounding nebulosity. With a low-power, wide-field eyepiece, the \u003cstrong\u003e419mm focal length\u003c\/strong\u003e will frame the entire nebula beautifully.\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 GT71's f\/5.9 focal ratio?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAn \u003cstrong\u003ef\/5.9 focal ratio\u003c\/strong\u003e is considered \"fast\" in astronomical terms. This allows the telescope to collect a significant amount of light in a shorter period compared to slower f\/8 or f\/10 systems. For imagers, this means you can capture more signal and detail in your sub-exposures, reducing total integration time.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat adapters are included with the William Optics Gran Turismo 71?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe GT71 includes two visual adapters. The first is an \u003cstrong\u003eM63 to 2\" adapter\u003c\/strong\u003e, allowing you to attach standard 2\" diagonals and eyepieces. The second is a \u003cstrong\u003e2\" to 1.25\" adapter\u003c\/strong\u003e, which steps down the connection to accommodate 1.25\" 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\u003eTriplet APO Prime Lens\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e71 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e419 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/5.9\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eImage Circle\u003c\/td\u003e\n\u003ctd\u003e44 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003e2.5\" R\u0026amp;P Focuser Compatible with EAF\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Travel\u003c\/td\u003e\n\u003ctd\u003e93 mm\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\u003eOptional Flattener\/Reducer\u003c\/td\u003e\n\u003ctd\u003eFLAT GT 1.0x, FLAT 6AIII 0.8x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDovetail Type\u003c\/td\u003e\n\u003ctd\u003eVixen \u0026amp; Arca-Swiss Compatible\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Length\u003c\/td\u003e\n\u003ctd\u003e392 mm (retracted) - 470 mm (extended)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOTA Weight\u003c\/td\u003e\n\u003ctd\u003e2.95 kg \/ 6.5 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\"\u003eGran Turismo 71 APO OTA\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 2\" Visual Back 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\"\u003e2\" to 1.25\" Visual Back 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\"\u003e360° Camera Angle Adjuster (CAA63)\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; Dovetail 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\"\u003eLens Cap\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":44967229260061,"sku":"WO-A-F71GTII-RD","price":1515.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-GT71-1.jpg?v=1722276408"},{"product_id":"william-optics-zenithstar-61ii-apo","title":"William Optics Zenithstar 61II APO","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e61mm Aperture Apochromatic Doublet Refractor\u003c\/li\u003e\n\u003cli\u003eOhara FPL-53 ED Glass Element\u003c\/li\u003e\n\u003cli\u003eFast f\/5.9 Focal Ratio for Wide-Field Imaging\u003c\/li\u003e\n\u003cli\u003eIncludes Flat61A Field Flattener\u003c\/li\u003e\n\u003cli\u003e2-inch Dual-Speed Rack \u0026amp; Pinion Focuser\u003c\/li\u003e\n\u003cli\u003eIntegrated Bahtinov Mask in Lens Cap\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\u003eDownloads\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 Zenithstar 61II APO Refractor\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Zenithstar 61II APO packages a color-free FPL-53 glass doublet and a precise 2-inch dual-speed focuser into a compact, portable optical tube. Designed as a complete wide-field imaging solution, this f\/5.9 refractor includes the essential Flat61A field flattener, delivering an instrument ready for demanding astrophotography right out of its included soft case.\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\u003eFPL-53 APO Doublet for Apochromatic Imaging\u003c\/h3\u003e\n\u003cp\u003eAt the core of the Zenithstar 61II is an air-spaced doublet objective featuring a genuine Ohara FPL-53 ED glass element. This apochromatic design virtually eliminates chromatic aberration, ensuring stars are rendered as sharp, high-contrast points of light without distracting purple fringing. The result is cleaner raw data with truer color fidelity, whether you're imaging emission nebulae or capturing the subtle hues in a star cluster.\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\u003eField-Ready Portability and CNC Mechanicals\u003c\/h3\u003e\n\u003cp\u003eEngineered for the traveling imager, the Z61II is built from CNC-machined aluminum for a rigid yet lightweight frame that holds collimation. The scope includes a Vixen-style dovetail for compatibility with a wide range of popular mounts, and a unique saddle handle bar that simplifies transport while also serving as a mounting point for guide scopes or other accessories. A custom-fit soft carrying case protects the instrument during travel to your favorite dark-sky site.\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\u003eImaging-Ready with a 2-Inch Focuser and Flat61A Flattener\u003c\/h3\u003e\n\u003cp\u003eWilliam Optics delivers the Z61II as a complete imaging system, not just an optical tube. The 2-inch dual-speed focuser provides the fine adjustment needed for critical focus, a process made simple by the Bahtinov mask cleverly integrated into the lens cap. Crucially, the package includes the matched Flat61A field flattener, which corrects for field curvature to ensure your images have sharp, pinpoint stars from the center to the corners of the frame—an essential component often sold separately.\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\"\u003eIs the William Optics Zenithstar 61II ready for astrophotography out of the box?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003e\u003cstrong\u003eYes.\u003c\/strong\u003e The Zenithstar 61II is packaged as a complete imaging solution. It includes the essential \u003cstrong\u003eFlat61A field flattener\u003c\/strong\u003e to ensure sharp stars across your sensor, a precise \u003cstrong\u003e2-inch dual-speed focuser\u003c\/strong\u003e for accurate adjustments, and an integrated \u003cstrong\u003eBahtinov mask\u003c\/strong\u003e in the lens cap for achieving critical focus easily.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the FPL-53 glass in the Zenithstar 61II benefit imaging?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Ohara \u003cstrong\u003eFPL-53 ED glass\u003c\/strong\u003e element provides apochromatic (APO) color correction. This minimizes chromatic aberration, or false color, which can appear as purple halos around bright stars. For imagers, this means sharper stars, higher contrast, and more accurate color data directly from the camera.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat makes the Zenithstar 61II a good portable or travel telescope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Z61II is designed for portability. Its compact size, lightweight CNC-machined aluminum body, and included padded soft carrying case make it easy to transport. It's an ideal \"grab-and-go\" scope for taking to dark sky sites or on trips.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow would the Zenithstar 61II frame a large target like the North American Nebula (NGC 7000)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Zenithstar 61II's wide field of view is perfectly suited for large deep-sky objects. When paired with a camera using an APS-C or smaller sensor, it can easily capture the entirety of massive targets like the North American Nebula (NGC 7000) or the Andromeda Galaxy (M31) in a single frame.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Zenithstar 61II for visual observing on a small tracking mount?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. While optimized for imaging, the Z61II is also an excellent visual instrument. Its light weight and Vixen dovetail make it a perfect match for portable tracking mounts like the Sky-Watcher Star Adventurer. With a 2-inch diagonal and a low-power, wide-field eyepiece, it provides stunning, expansive views of the Milky Way.\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 saddle handle bar on the Zenithstar 61II?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe handle bar serves two functions. It provides a secure and balanced grip for carrying the telescope and placing it on a mount. It also features a Vixen-style saddle, allowing you to mount accessories like a small guide scope or a red dot finder directly on top of the optical tube.\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\u003eAvailable Options\u003c\/td\u003e\n\u003ctd\u003eGrey, Gold\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\"\u003eZenithstar 61 II APO OTA\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\"\u003eFlat61A Field Flattener\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 with 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\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eVixen-Style Dovetail 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\"\u003eLens Cap with Integrated Bahtinov Mask\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 Carrying 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\u003cli\u003e\n\u003cul class=\"DAV-grid\"\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":"Grey","offer_id":44967230898461,"sku":"WO-A-Z61IITG","price":962.0,"currency_code":"CAD","in_stock":true},{"title":"Gold","offer_id":51501958594845,"sku":"WO-A-Z61IIGD","price":962.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/WO-Z-61-II-Grey-1.jpg?v=1722104068"},{"product_id":"william-optics-fluorostar-91","title":"William Optics Fluorostar 91","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e91mm Aperture Apochromatic Triplet\u003c\/li\u003e\n\u003cli\u003eFPL-53 Glass for Superior Color Correction\u003c\/li\u003e\n\u003cli\u003eStrehl Ratio Exceeding 0.95\u003c\/li\u003e\n\u003cli\u003e3.3\" Dual-Speed Rack \u0026amp; Pinion Focuser\u003c\/li\u003e\n\u003cli\u003e360° Field Rotator for Image Framing\u003c\/li\u003e\n\u003cli\u003eIntegrated Bahtinov Mask in Lens Cap\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 Fluorostar 91 APO Triplet Refractor\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Fluorostar 91 refractor combines a 91mm FPL-53 triplet objective with apochromatic correction, delivering images that demonstrate a Strehl ratio exceeding 0.95. Its robust 3.3\" rack and pinion focuser supports heavy imaging trains without flexure, while the 4.2 kg base tube weight ensures portability for demanding use in the field.\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\u003e91mm FPL-53 Triplet Optics: Strehl Ratio \u0026gt; 0.95 for High-Contrast Imaging\u003c\/h3\u003e\n\u003cp\u003eAt the core of the Fluorostar 91 is an air-spaced triplet objective featuring premium FPL-53 glass. This design virtually eliminates chromatic aberration, producing tack-sharp stars with pure color rendition. With a guaranteed Strehl ratio of over 0.95, this optic delivers maximum contrast, making it ideal for resolving fine planetary detail and capturing faint nebulosity against a dark sky background.\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\u003e3.3\" Rack \u0026amp; Pinion Focuser with 360° Field Rotator\u003c\/h3\u003e\n\u003cp\u003eEngineered for astrophotography, the FLT91 is equipped with a heavy-duty 3.3\" rack and pinion focuser. The dual-speed mechanism allows for coarse and fine adjustments, critical for achieving perfect focus with a camera. The entire focuser assembly includes a 360° field rotator for precise image framing, and the optical train terminates in a 2\" Rotolock adapter that provides a secure, self-centering grip on diagonals and 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\u003eImaging-Focused Design: Integrated Bahtinov Mask \u0026amp; 4.2 kg Tube Weight\u003c\/h3\u003e\n\u003cp\u003eEvery feature of the Fluorostar 91 is designed with the imager in mind. The lens cap contains an integrated Bahtinov mask, simplifying the process of achieving critical focus. An integrated saddle handle provides a secure grip and a mounting point for guide scopes or other accessories. Weighing only 4.2 kg (5.6 kg fully equipped), the FLT91 is easily managed by mid-sized equatorial mounts, creating a powerful yet portable deep-sky imaging system that comes protected in its own soft carry case.\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 makes the William Optics Fluorostar 91 an \"apochromatic triplet\"?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Fluorostar 91 is an \u003cstrong\u003eapochromatic triplet\u003c\/strong\u003e because it uses a three-element objective lens, including one element made from high-performance \u003cstrong\u003eFPL-53 glass\u003c\/strong\u003e. This combination brings the red, green, and blue wavelengths of light to the same focal point, eliminating distracting color fringing (chromatic aberration) for sharp, high-contrast images.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the 360° rotator on the FLT91 help with astrophotography?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e360° field rotator\u003c\/strong\u003e allows you to change the orientation of your camera without loosening any screws or affecting focus. This is essential for composing your shot, letting you frame celestial objects like the Veil Nebula or the Rho Ophiuchi cloud complex perfectly within your sensor's field of view.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhich field flatteners are compatible with the Fluorostar 91?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe William Optics FLT91 is designed to be compatible with several William Optics flatteners, allowing for precise back-focus adjustments and a corrected field for various sensor sizes. Recommended models include:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eFlat 6AIII\u003c\/li\u003e\n\u003cli\u003eFlat 68III\u003c\/li\u003e\n\u003cli\u003eUltra Flat 91\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 Fluorostar 91 perform on emission nebulae like the North American Nebula (NGC 7000)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe FLT91's FPL-53 optics provide excellent color correction, especially in the red end of the spectrum where hydrogen-alpha emissions from nebulae like NGC 7000 are dominant. This results in tight, well-defined stars without the blue or violet halos that can plague lesser refractors, allowing the faint details of the nebula to stand out.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the William Optics FLT91 for high-magnification planetary viewing of Jupiter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAbsolutely. The high Strehl ratio (\u003cstrong\u003e\u0026gt; 0.95\u003c\/strong\u003e) of the Fluorostar 91 ensures maximum contrast and sharpness. When seeing conditions are good, you can push the magnification to view fine details like the cloud bands of Jupiter, the Cassini Division in Saturn's rings, and subtle surface features on Mars.\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 integrated Bahtinov mask in the FLT91's lens cap?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe integrated \u003cstrong\u003eBahtinov mask\u003c\/strong\u003e is a focusing aid that creates a distinct diffraction pattern around a bright star. When the central spike is perfectly centered between the other two, you have achieved critical focus. This built-in tool saves time and removes the guesswork from focusing, ensuring your astrophotos are as sharp as possible.\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\u003eApochromatic Triplet Refractor\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAperture\u003c\/td\u003e\n\u003ctd\u003e91mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eObjective Glass\u003c\/td\u003e\n\u003ctd\u003eFPL-53\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eStrehl Ratio\u003c\/td\u003e\n\u003ctd\u003e\u0026gt; 0.95\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003e3.3\" Dual-Speed Rack \u0026amp; Pinion\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eField Rotator\u003c\/td\u003e\n\u003ctd\u003e360°\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eConnection\u003c\/td\u003e\n\u003ctd\u003e2\" Rotolock Adapter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFeatures\u003c\/td\u003e\n\u003ctd\u003eIntegrated Saddle Handle, Built-in Bahtinov Mask\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight (Tube Only)\u003c\/td\u003e\n\u003ctd\u003e4.2 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight (Fully Equipped)\u003c\/td\u003e\n\u003ctd\u003e5.6 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAvailable Colors\u003c\/td\u003e\n\u003ctd\u003eGrey, Gold, Red\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/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":"Grey","offer_id":44967782088989,"sku":"WO-T-FLT-91SG-RP33","price":3033.0,"currency_code":"CAD","in_stock":true},{"title":"Gold","offer_id":44967782023453,"sku":"WO-T-FLT-91GD-RP33","price":2877.0,"currency_code":"CAD","in_stock":true},{"title":"Red","offer_id":44967782056221,"sku":"WO-T-FLT-91RD-RP33","price":2877.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Williamo-Optics-FLT91-1.jpg?v=1722276083"},{"product_id":"william-optics-fluorostar-120","title":"William Optics Fluorostar 120","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e120mm Aperture\u003c\/li\u003e\n\u003cli\u003eFPL-53 Triplet Apochromatic Optics\u003c\/li\u003e\n\u003cli\u003e3.3\" Rack \u0026amp; Pinion Focuser\u003c\/li\u003e\n\u003cli\u003eBuilt-in Camera Angle Rotator\u003c\/li\u003e\n\u003cli\u003eIntegrated Bahtinov Mask\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 Fluorostar 120 Triplet APO Refractor\u003c\/h2\u003e\n      \u003cp\u003eThe William Optics Fluorostar 120 refractor combines a 120mm apochromatic triplet objective made with FPL-53 glass and a robust 3.3\" rack and pinion focuser for high-contrast, color-free astrophotography. Its imaging train begins with a native M92 thread and includes adapters for a 2\" RotoLock and a 1.25\" visual back, ensuring broad compatibility with your cameras and 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\u003eA 120mm FPL-53 Triplet for Pure-Color Imaging\u003c\/h3\u003e\n      \u003cp\u003eAt the heart of the Fluorostar 120 lies an air-spaced triplet objective featuring premium FPL-53 glass. This apochromatic design provides outstanding correction of chromatic aberration, eliminating the false color halos around bright stars that can compromise contrast and detail in lesser refractors. The result is a pristine, high-contrast image with pinpoint stars on a dark background, essential for capturing the subtle colors of nebulae and galaxies.\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\u003eThe 3.3\" Rack \u0026amp; Pinion Focuser and Rotator System\u003c\/h3\u003e\n      \u003cp\u003eBuilt to handle heavy imaging loads, the heavy-duty 3.3\" rack and pinion focuser provides a rigid, zero-flexure platform for large cameras, filter wheels, and off-axis guiders. A built-in rotator allows you to frame your target perfectly without loosening the camera. The robust build necessary to support a full imaging rig means this is not a lightweight instrument; you will need a substantial mount to carry it effectively.\u003c\/p\u003e\n      \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eNative Connection:\u003c\/strong\u003e The focuser drawtube terminates in a secure M92 thread.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003e2-Inch Adapter:\u003c\/strong\u003e An included adapter steps the connection down to a William Optics 2\" RotoLock, a self-centering system for accessories.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003e1.25-Inch Adapter:\u003c\/strong\u003e For visual use or smaller guide cameras, a final adapter provides a standard 1.25\" visual back.\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\u003eIntegrated Design: From M92 Threads to a Losmandy Plate\u003c\/h3\u003e\n      \u003cp\u003eThe Fluorostar 120 is engineered with practical features that streamline your imaging sessions. An integrated, patented Bahtinov Mask, built into the lens cap, is significantly lighter than traditional metal masks and makes achieving critical focus simple. The CNC-machined saddle handle bar not only provides a secure grip but also accepts Vixen-style mounting for guidescopes like the William Optics Uniguide. The entire optical tube assembly is secured by a sturdy Losmandy-style dovetail plate for a solid connection to your equatorial mount.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\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\"\u003eWhat makes the Fluorostar 120's FPL-53 triplet design ideal for astrophotography?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe \u003cstrong\u003eFPL-53 glass\u003c\/strong\u003e in the Fluorostar 120's triplet lens system provides excellent correction of chromatic aberration. This means stars appear as sharp, color-pure points of light without distracting purple or blue halos, resulting in higher contrast and more natural-looking astrophotos.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the integrated Bahtinov mask on the Fluorostar 120 simplify focusing?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe patented Bahtinov Mask is built directly into the lens cap of the Fluorostar 120. To use it, you simply uncap the telescope, aim at a bright star, and adjust focus until the central diffraction spike is perfectly centered between the other two. This provides a fast, precise, and repeatable method for achieving critical focus every time you set up.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat kind of imaging train can the Fluorostar 120's 3.3\" focuser support?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe heavy-duty \u003cstrong\u003e3.3\" rack and pinion focuser\u003c\/strong\u003e is designed to handle significant weight without slipping or flexing. It can easily support a full astrophotography setup, including a cooled astronomy camera, a large filter wheel, and an off-axis guider, ensuring your entire imaging train remains stable throughout the night.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the Fluorostar 120 perform when imaging the hydrogen-alpha regions in the Cygnus Loop (Veil Nebula)?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe Fluorostar 120's apochromatic optics excel at imaging emission nebulae like the Veil Nebula. The high-contrast views and excellent color correction allow the fine, filamentary details of the hydrogen-alpha structures to be captured with exceptional clarity against a dark sky background, especially when paired with narrowband filters.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat are the benefits of the Fluorostar 120's rotator when framing a large target like 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 built-in camera angle rotator on the Fluorostar 120 lets you adjust the orientation of your camera without having to loosen any other components in the imaging train. This is crucial for large targets like M31, as it allows you to precisely align the galaxy's long axis with your camera sensor's diagonal for the most compelling composition.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat mounting hardware is included with the William Optics Fluorostar 120?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe William Optics Fluorostar 120 comes with essential mounting hardware for immediate setup. This includes a CNC-machined handle that doubles as a Vixen-style saddle for accessories, mounting rings, and a Losmandy-style dovetail plate for secure attachment to a compatible equatorial mount.\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\u003eAvailable Options\u003c\/td\u003e\n\u003ctd\u003eRed, Gold, Space Gray\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\"\u003eM92 Rotator 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\"\u003eM92 to 2\" RotoLock 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\"\u003e2\" to 1.25\" Visual Back Adapter\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":44967917682973,"sku":"WO-A-F120RD-RP33","price":4965.0,"currency_code":"CAD","in_stock":true},{"title":"Gold","offer_id":44967917650205,"sku":"WO-A-F120GD-RP33","price":4965.0,"currency_code":"CAD","in_stock":true},{"title":"Space Gray","offer_id":44967917715741,"sku":"WO-A-F120TG-RP33","price":4965.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-FLT120-1.jpg?v=1722276874"},{"product_id":"william-optics-gran-turismo-wifd-81","title":"William Optics Gran Turismo WIFD 81","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e81mm Aperture Triplet Apochromatic Refractor\u003c\/li\u003e\n\u003cli\u003eFPL-53 Ohara Glass for Superior Color Correction\u003c\/li\u003e\n\u003cli\u003eWilliam Optics Internal Focusing Design (WIFD)\u003c\/li\u003e\n\u003cli\u003eIncluded Dual-Side Vixen\/Arca-Swiss Mounting Plate\u003c\/li\u003e\n\u003cli\u003eIntegrated Bahtinov Mask Focusing Aid\u003c\/li\u003e\n\u003cli\u003ePadded Soft Carry Case for Transport and Storage\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 Gran Turismo WIFD 81 Apochromatic Refractor\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Gran Turismo WIFD 81 combines an 81mm triplet objective with a robust M92 threaded connection for a stable, zero-flexure imaging train. The included M92 to M63 adapter ensures compatibility with a wide range of correctors and cameras, making this apochromat a versatile core for any astrophotography setup.\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\u003e81mm FPL-53 Triplet: Apochromatic Optics for Pure Color\u003c\/h3\u003e\n\u003cp\u003eAt the heart of the Gran Turismo 81 is an air-spaced triplet objective featuring premium FPL-53 glass from Ohara, Japan. This design achieves apochromatic correction, virtually eliminating chromatic aberration for true-to-life color and razor-sharp stars. You see no distracting purple fringing on bright stars like Vega or Sirius, only clean, high-contrast detail whether you're observing visually or imaging deep-sky objects.\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 \u0026amp; M92 Adapter: A Zero-Flexure Imaging Platform\u003c\/h3\u003e\n\u003cp\u003eThe proprietary William Optics Internal Focusing Design (WIFD) provides an exceptionally smooth and stable focusing mechanism critical for astrophotography. Unlike traditional focusers that move a drawtube, the WIFD moves the lens assembly internally, meaning your camera and imaging train remain fixed. This design eliminates sag and tilt, preserving perfect alignment even with heavy equipment attached to the M92 threaded rear port.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncluded Hardware:\u003c\/strong\u003e The telescope arrives ready for the field with mounting rings, a sturdy handle bar, and a versatile dual-side plate compatible with both Vixen and Arca-Swiss style saddles.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFocusing Perfected:\u003c\/strong\u003e A Bahtinov mask is cleverly integrated into the lens cap, providing a simple and precise way to achieve critical focus every time.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImaging Train Note:\u003c\/strong\u003e For serious astrophotography, a dedicated field flattener is required to achieve a perfectly flat field across the entire sensor. This is an optional accessory and is not included with the optical tube.\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 Gran Turismo WIFD 81 ideal for astrophotography?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003eGran Turismo WIFD 81\u003c\/strong\u003e is built for imaging. Its core strengths are the FPL-53 triplet lens for color-free images and the WIFD internal focuser. The WIFD prevents focuser sag and tilt, which is a common issue with external focusers when using heavy cameras and filter wheels.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow would the GT81 WIFD perform on a target like the Andromeda Galaxy (M31)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003eGT81 WIFD\u003c\/strong\u003e is an excellent wide-field instrument for large targets like the Andromeda Galaxy (M31) or the North American Nebula (NGC 7000). With a compatible field flattener, you can capture these expansive objects in a single frame with sharp stars from edge to edge.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eI have a mount with a Vixen-style saddle. Do I need to buy a new dovetail for the GT81 WIFD?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, you do not. The \u003cstrong\u003eGT81 WIFD\u003c\/strong\u003e includes a dual-side mounting plate that is compatible with both standard Vixen-style saddles and Arca-Swiss saddles, offering broad compatibility with most astronomical mounts right 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 benefit of the FPL-53 glass in the Gran Turismo 81's triplet lens?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003e\u003cstrong\u003eFPL-53\u003c\/strong\u003e is a high-grade, extra-low dispersion (ED) glass that provides superior correction of chromatic aberration, or \"color fringing.\" This means light of all colors comes to the same sharp focus, resulting in higher contrast, truer star colors, and finer visible detail compared to standard doublet or ED glass designs.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes the William Optics GT81 WIFD come with a field flattener?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, a field flattener is a required but \u003cstrong\u003eoptional accessory\u003c\/strong\u003e for astrophotography. While the telescope provides a sharp central image, a flattener is necessary to correct the natural field curvature of the optics and ensure pinpoint stars across the entire sensor of a DSLR or dedicated astronomy camera.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is \"WIFD\" and why is it better than a traditional focuser?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003e\u003cstrong\u003eWIFD\u003c\/strong\u003e stands for William Optics Internal Focusing Design. Instead of an external drawtube that extends and retracts, the WIFD moves the objective lens internally. This creates a sealed, rigid system with zero image shift or tilt, providing a more stable and reliable platform for focusing, especially with the weight of an imaging setup.\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\u003e81mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Design\u003c\/td\u003e\n\u003ctd\u003eApochromatic Triplet\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eGlass Type\u003c\/td\u003e\n\u003ctd\u003eFPL-53 Ohara Glass\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Design\u003c\/td\u003e\n\u003ctd\u003eWIFD (William Optics Internal Focusing Design)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAvailable Colors\u003c\/td\u003e\n\u003ctd\u003eRed, Gold, Grey\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\"\u003eGran Turismo 81 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\"\u003eM92 to M63 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 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\"\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":"Red","offer_id":44968075034909,"sku":"WO-T-GT-81RD-WIFD","price":3033.0,"currency_code":"CAD","in_stock":true},{"title":"Gold","offer_id":48966030000413,"sku":"WO-T-GT-81GD-WIFD","price":3033.0,"currency_code":"CAD","in_stock":true},{"title":"Grey","offer_id":48966030033181,"sku":"WO-T-GT-81SG-WIFD","price":3033.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-GT81-WIFD-1.jpg?v=1722276662"},{"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-pleiades-68-astrograph-f-3-8-7-element-wifd","title":"William Optics Pleiades 68 Astrograph F\/3.8 7-Element WIFD","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e68mm Aperture 7-Element Astrograph\u003c\/li\u003e\n\u003cli\u003eFast f\/3.8 Focal Ratio\u003c\/li\u003e\n\u003cli\u003e260mm Focal Length\u003c\/li\u003e\n\u003cli\u003e48mm Full-Frame Image Circle\u003c\/li\u003e\n\u003cli\u003eWeighs only 2.98 kg (6.57 lbs)\u003c\/li\u003e\n\u003cli\u003eWIFD Focuser with EAF Compatibility\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 Pleiades 68 Astrograph F\/3.8 7-Element WIFD\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Pleiades 68 Astrograph combines a fast f\/3.8 optical system with a 68mm aperture to capture vast deep-sky targets in a single frame. Its 7-element design, incorporating three Super ED glass elements, delivers a flat, color-corrected 48mm image circle without requiring an external flattener. With a wide 260mm focal length and an OTA weight of just 2.98 kg, this astrograph is engineered for imagers seeking a portable, high-speed instrument that fully illuminates full-frame sensors.\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\u003ePleiades 68 Optics: A 7-Element, f\/3.8 Design with 3 Super ED Elements\u003c\/h3\u003e\n\u003cp\u003eThis astrograph is built around a sophisticated 7-element optical formula specifically for imaging. The f\/3.8 focal ratio dramatically reduces exposure times, allowing you to collect more data on faint nebulae and galaxies in a single night. Three Super ED glass elements are used to minimize chromatic aberration, ensuring star colors are rendered accurately and pinpoint sharp across the entire field.\u003c\/p\u003e\n\u003cp\u003eThe 260mm focal length provides an expansive field of view ideal for large targets like the Andromeda Galaxy (M31) or the Rho Ophiuchi cloud complex. Because the optical correction is integrated, you don't need to purchase or calculate spacing for a separate flattener, simplifying your imaging train and eliminating a potential source of tilt.\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\u003e48mm Image Circle and WIFD Focuser: Full-Frame Illumination and Stability\u003c\/h3\u003e\n\u003cp\u003eThe Pleiades 68 delivers a corrected and illuminated 48mm image circle, exceeding the requirements of full-frame (36x24mm) sensors and providing ample coverage for APS-C and M4\/3 cameras. This ensures your images are free from vignetting and maintain consistent star shapes from the center to the corners of the frame.\u003c\/p\u003e\n\u003cp\u003eFocusing is managed by the robust William Optics Internal Focuser Design (WIFD), a rack-and-pinion system that moves the optics internally. This design prevents sag and flexure common with heavy camera payloads, maintaining critical focus throughout an imaging session. The focuser is fully compatible with popular electronic auto-focusers (EAF) for automated, repeatable precision.\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\u003eField-Ready at 2.98 kg: Integrated Rotator, Tilt Adjuster, and Adapters\u003c\/h3\u003e\n\u003cp\u003eEngineered for portability and immediate use, the Pleiades 68 OTA weighs only 2.98 kg (6.57 lbs). The package includes a complete set of accessories to build a rigid imaging train right out of the box. An integrated camera angle rotator allows for precise framing, while the included tilt adjuster lets you dial in perfect sensor orthogonality.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eVersatile Mounting:\u003c\/strong\u003e The dual-side Vixen and Arca-Swiss dovetail plate provides native compatibility with a wide range of equatorial mounts and tripod heads.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncluded Adapters:\u003c\/strong\u003e M63 to M48 and M63 to M54 adapters are supplied, ensuring you can connect most dedicated astronomy cameras and DSLRs\/mirrorless cameras with the appropriate T-ring.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eComplete Kit:\u003c\/strong\u003e The astrograph ships in a soft carry case and includes a handle bar, mounting ring, riser blocks, and a Bahtinov mask cap for achieving perfect focus.\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 Pleiades 68 need a separate field flattener?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. The \u003cstrong\u003ePleiades 68\u003c\/strong\u003e is a 7-element astrograph with an integrated flattener in its optical design. It is engineered to produce a flat field across its entire \u003cstrong\u003e48mm image circle\u003c\/strong\u003e without any additional corrective optics.\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 camera with the Pleiades 68 Astrograph?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The Pleiades 68 is designed for full-frame cameras. Its \u003cstrong\u003e48mm image circle\u003c\/strong\u003e provides full illumination for standard 36x24mm sensors, ensuring you can capture images without vignetting. The included M48 and M54 adapters accommodate common connections for full-frame astronomy cameras and DSLRs\/mirrorless bodies.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the 260mm focal length of the Pleiades 68 frame 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 \u003cstrong\u003e260mm focal length\u003c\/strong\u003e, when paired with a full-frame sensor, provides a very wide field of view (approximately 7.8° x 5.2°). This is perfectly suited for framing enormous emission nebulae like the North American Nebula (NGC 7000) and the Veil Nebula complex in their entirety, with room to spare.\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 Pleiades 68?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe William Optics Internal Focuser Design (WIFD) moves the optical elements internally rather than moving the camera externally. This offers two main advantages:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eNo Sag:\u003c\/strong\u003e It creates a more rigid imaging train that is less susceptible to flexure, especially with heavy cameras and filter wheels.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFixed Length:\u003c\/strong\u003e The overall length of the optical tube does not change during focusing, which can help with balance and clearance on some mounts.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eIt is also compatible with EAF systems for automated focusing.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat does the included tilt adjuster for the Pleiades 68 do?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe tilt adjuster allows you to make micro-adjustments to the angle of your camera sensor relative to the optical axis. This is crucial for achieving perfectly sharp stars across the entire frame, as it corrects for any slight tilt that may exist in your camera or focuser connection.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat kind of mount is required for the 3.83 kg Pleiades 68?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWith a total weight of \u003cstrong\u003e3.83 kg (8.44 lbs)\u003c\/strong\u003e including rings and dovetail, the Pleiades 68 is very lightweight. It can be carried easily by portable star trackers and smaller equatorial mounts in the 20-25 lb payload class, such as a Sky-Watcher HEQ5 or iOptron CEM26, making it an excellent choice for a mobile imaging setup.\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\u003e7-Element Astrograph\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLens Elements\u003c\/td\u003e\n\u003ctd\u003e3x Super ED Glass\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e68 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e260 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eImage Circle\u003c\/td\u003e\n\u003ctd\u003e48 mm\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\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003eWIFD Rack \u0026amp; Pinion, EAF Compatible\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Travel\u003c\/td\u003e\n\u003ctd\u003e45 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\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 \/ Arca-Swiss Dual Type\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Length\u003c\/td\u003e\n\u003ctd\u003e366 mm - 410 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOTA Weight\u003c\/td\u003e\n\u003ctd\u003e2.98 kg (6.57 lbs)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTotal Weight\u003c\/td\u003e\n\u003ctd\u003e3.83 kg (8.44 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\"\u003ePleiades 68 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\"\u003eCamera Angle 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\"\u003eTilt Adjuster\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\"\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\"\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":"Default Title","offer_id":48603138654493,"sku":"WO-T-P-68BU","price":3033.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Pleiades-68-perspective-1_a547ae6a-4742-4cbd-aba3-6ce858e67b9b.webp?v=1717690953"},{"product_id":"william-optics-pleiades-111-astrograph-f-4-8-7-element-wifd","title":"William Optics Pleiades 111 Astrograph F\/4.8 7-element WIFD","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e111mm Aperture 7-Element Astrograph\u003c\/li\u003e\n\u003cli\u003e528mm Focal Length at a fast f\/4.8\u003c\/li\u003e\n\u003cli\u003e45mm Image Circle for Full-Frame Sensors\u003c\/li\u003e\n\u003cli\u003eWilliam Optics Internal Focus Design (WIFD)\u003c\/li\u003e\n\u003cli\u003eIntegrated Rotator and Tilt Adjuster\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 Pleiades 111 Astrograph F\/4.8 7-element WIFD\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Pleiades 111 Astrograph integrates a 7-element optical system into a 111mm aperture to deliver a perfectly flat 45mm image circle without an external flattener. Its fast f\/4.8 focal ratio at a 528mm focal length is engineered for serious astrophotographers, capturing expansive deep-sky targets with full-frame cameras. The entire optical train weighs 10.31 kg and features the William Optics Internal Focus Design (WIFD) for absolute stability with heavy imaging loads.\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\u003eSeptuplet f\/4.8 Optics: A 45mm Flat-Field Imaging System\u003c\/h3\u003e\n\u003cp\u003eThe core of the Pleiades 111 is its 7-element apochromatic lens system, which incorporates three Super ED glass elements to achieve exceptional color correction. This sophisticated design produces a native 45mm image circle that is perfectly flat, eliminating the need for a separate flattener and simplifying your imaging train. At a fast f\/4.8, you can collect more light in less time, revealing faint nebulosity and detail in distant galaxies.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eNo Flattener Required:\u003c\/strong\u003e The Petzval-like optical formula corrects for field curvature internally, ensuring sharp, pinpoint stars across a full-frame sensor.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e111mm Aperture at 528mm:\u003c\/strong\u003e This combination provides a wide field of view, ideal for framing large targets like the Andromeda Galaxy (M31) or the North American Nebula (NGC 7000).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSuper ED Glass:\u003c\/strong\u003e Three low-dispersion elements minimize chromatic aberration, resulting in high-contrast images with pure, vibrant star colors.\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\u003eWIFD Focuser: 35mm of Stable, Internal-Focus Travel\u003c\/h3\u003e\n\u003cp\u003eWilliam Optics' innovative Internal Focus Design (WIFD) eliminates the primary source of flexure in traditional refractors: the moving drawtube. By moving the lens assembly internally over a 35mm travel range, the focuser body remains fixed and rigid. This design maintains perfect optical alignment and supports heavy camera packages without sagging, ensuring consistent focus and round stars throughout your imaging session.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eZero Image Shift:\u003c\/strong\u003e The internal rack-and-pinion mechanism provides smooth, precise focus adjustments without any lateral movement of the image.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEAF Compatible:\u003c\/strong\u003e The WIFD focuser is fully compatible with popular electronic auto-focusers, enabling automated and repeatable focusing routines.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRigid and Compact:\u003c\/strong\u003e With no external drawtube, the telescope maintains a more compact and stable profile as it slews across the sky.\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\u003eIntegrated Rotator and Tilt Adjuster: Precision Camera Framing\u003c\/h3\u003e\n\u003cp\u003eThe Pleiades 111 is built for precision from the focuser to the sensor. An integrated camera angle rotator allows you to frame your target perfectly without loosening any connections in your imaging train. To achieve flawless corner-to-corner sharpness, a built-in tilt adjuster lets you dial in the orthogonality of your camera sensor to the optical axis, correcting for any minor tilt in your setup.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e360° Camera Rotation:\u003c\/strong\u003e Easily compose your images by rotating the entire camera and filter wheel assembly with a smooth, lockable mechanism.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncluded Adapters:\u003c\/strong\u003e The astrograph ships with both M48 and M54 camera adapters, providing direct, threaded connections for most modern astronomy cameras and DSLRs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLosmandy-Style Dovetail:\u003c\/strong\u003e A robust Losmandy-D dovetail plate provides a secure connection to your equatorial mount, capable of handling the 10.31 kg total weight.\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 to buy a separate flattener for the Pleiades 111 Astrograph?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. The William Optics Pleiades 111 has a 7-element optical design that corrects for field curvature internally. It produces a native \u003cstrong\u003e45mm flat image circle\u003c\/strong\u003e without requiring 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\"\u003eWhat are the advantages of the WIFD internal focuser on the Pleiades 111?\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 lens assembly internally rather than using an external drawtube. This offers two key advantages:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncreased Rigidity:\u003c\/strong\u003e It prevents focuser sag, which is critical when using heavy cameras, filter wheels, and off-axis guiders.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConsistent Collimation:\u003c\/strong\u003e By keeping the camera and accessories fixed, it maintains perfect optical alignment as you focus.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the Pleiades 111's 528mm focal length frame large targets like the Andromeda Galaxy (M31)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e528mm focal length\u003c\/strong\u003e paired with a full-frame sensor provides a wide field of view, approximately 3.9° x 2.6°. This is perfectly suited for capturing the entire Andromeda Galaxy (M31), including its faint outer arms and satellite galaxies M32 and M110, in a single frame.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the f\/4.8 focal ratio of the Pleiades 111 good for narrowband imaging?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, the fast \u003cstrong\u003ef\/4.8 focal ratio\u003c\/strong\u003e is a significant advantage for narrowband imaging. It allows you to gather signal on faint emission nebulae, like the Cygnus Loop or the Heart Nebula (IC 1805), much faster than with slower f\/6 or f\/7 systems, reducing your total exposure time for each filter.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat kind of mount is required for the William Optics Pleiades 111?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Pleiades 111 has a total weight of \u003cstrong\u003e10.31 kg (22.73 lbs)\u003c\/strong\u003e when fully assembled with rings and dovetail. For stable astrophotography, you should use a German Equatorial Mount with a payload capacity of at least 40 lbs (18 kg) to ensure precise tracking and guiding.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat do the included tilt and rotator adapters on the Pleiades 111 do?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThese are critical tools for advanced imaging. The \u003cstrong\u003erotator\u003c\/strong\u003e allows you to change the orientation of your camera to perfectly frame your target without changing focus. The \u003cstrong\u003etilt adjuster\u003c\/strong\u003e lets you make micro-adjustments to the angle of your camera sensor to ensure it is perfectly perpendicular to the light path, guaranteeing sharp stars across the entire field of view.\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\u003e7-Element Astrograph with 3x Super ED Glass Elements\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAperture\u003c\/td\u003e\n\u003ctd\u003e111 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e528 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\u003e45 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\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Travel\u003c\/td\u003e\n\u003ctd\u003e35 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\u003eCamera Support\u003c\/td\u003e\n\u003ctd\u003eFull Frame, APS-C, M4\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eIncluded Camera Adapters\u003c\/td\u003e\n\u003ctd\u003eM48, M54\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDovetail\u003c\/td\u003e\n\u003ctd\u003eLosmandy-D Style\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Length (Retracted\/Extended)\u003c\/td\u003e\n\u003ctd\u003e645 mm - 785 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOTA Weight\u003c\/td\u003e\n\u003ctd\u003e7.95 kg \/ 17.53 lbs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTotal Weight (inc. rings\/dovetail)\u003c\/td\u003e\n\u003ctd\u003e10.31 kg \/ 22.73 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\"\u003eTilt Adjuster\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\"\u003eCamera Angle 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\"\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\"\u003eM54 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\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":48603506409757,"sku":"WO-T-P-111BU","price":5793.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Pleiades-111-pers-2.webp?v=1717694571"},{"product_id":"william-optics-pleiades-181-astrograph-f-5-5-7-element-wifd","title":"William Optics Pleiades 181 Astrograph F\/5.5 7-element with 3 ED glasses","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e181mm Aperture, 998mm Focal Length\u003c\/li\u003e\n\u003cli\u003eFast f\/5.5 Focal Ratio\u003c\/li\u003e\n\u003cli\u003e7-Element Optical Design with 3 Super ED Glass Elements\u003c\/li\u003e\n\u003cli\u003e55mm Corrected Image Circle\u003c\/li\u003e\n\u003cli\u003e4.1-inch Rack \u0026amp; Pinion Focuser\u003c\/li\u003e\n\u003cli\u003eIntegrated Petzval design requires no additional flattener\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 Pleiades 181 Astrograph f\/5.5\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Pleiades 181 is a dedicated imaging instrument built around a 7-element optical design that delivers a massive 55mm corrected image circle. Its 181mm objective and fast f\/5.5 focal ratio are corrected by three Super ED glass elements, providing a flat, color-pure field across medium format sensors without requiring an external flattener. With a robust 4.1-inch Rack \u0026amp; Pinion focuser and a total weight of 18.7 kg, this astrograph is engineered from the ground up for serious, large-format astrophotography.\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 7-Element, 181mm Optical System for Flat-Field Imaging\u003c\/h3\u003e\n\u003cp\u003eThe Pleiades 181 combines a large 181mm aperture with a 998mm focal length, resulting in a fast f\/5.5 system ideal for capturing faint detail in nebulae and galaxies. The optical core is a 7-element Petzval-like design that includes three Super ED glass elements to virtually eliminate chromatic aberration, ensuring stars remain tight, color-neutral points of light.\u003c\/p\u003e\n\u003cp\u003eBecause the field-correcting elements are integrated into the main optical train, the Pleiades 181 produces a natively flat field. This eliminates the need to purchase and correctly space a separate flattener, simplifying your imaging train and guaranteeing optimal correction right out of the box.\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 Medium Format Sensors\u003c\/h3\u003e\n\u003cp\u003eEngineered specifically for large-format imaging, the Pleiades 181 illuminates a corrected 55mm image circle. This provides complete, unvignetted coverage for medium format sensors and easily accommodates full-frame, APS-C, and M4\/3 cameras with room to spare.\u003c\/p\u003e\n\u003cp\u003eThe expansive corrected field allows you to frame the largest deep-sky objects without compromise and gives you significant flexibility in composing your shots. For imagers using full-frame or smaller sensors, the edge-to-edge correction ensures perfectly round stars across the entire frame, even on the most demanding, high-resolution 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\u003eEngineered for Imaging: 4.1-inch Focuser and Integrated Adapters\u003c\/h3\u003e\n\u003cp\u003eTo handle the weight of modern imaging packages, the Pleiades 181 is equipped with a heavy-duty 4.1-inch Rack \u0026amp; Pinion focuser. With 43mm of precise focus travel and native compatibility with popular electronic auto-focusers (EAF), it provides a rigid, repeatable platform for achieving critical focus, even with heavy cameras and filter wheels.\u003c\/p\u003e\n\u003cp\u003eThe astrograph includes a complete set of adapters to streamline camera connection. The package contains M68, M54, and M48 adapters, along with a built-in rotator for framing and a tilt adjuster for perfecting sensor alignment. This comprehensive solution ensures you can connect and optimize your imaging train immediately.\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\u003eRobust Mechanical Design: 18.7 kg Total Weight and Ergonomic Handling\u003c\/h3\u003e\n\u003cp\u003eThe Pleiades 181 is a substantial instrument, with an optical tube assembly weight of 15 kg (33.07 lbs) and a total equipped weight of 18.7 kg (41.23 lbs). This requires a high-capacity equatorial mount to ensure stability and tracking accuracy. The telescope comes with a standard Losmandy-style dovetail plate for secure mounting.\u003c\/p\u003e\n\u003cp\u003eTo aid in handling and setup, the design incorporates William Optics' signature features, including the innovative Cosmos Steering Wheel for easier lifting and positioning. The tube extends from a retracted length of 1231mm to 1496mm with the dew shield in place, providing excellent stray light and moisture protection for the objective lens.\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 class of mount is required for the Pleiades 181 astrograph?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWith a total weight of \u003cstrong\u003e18.7 kg (41.23 lbs)\u003c\/strong\u003e, the Pleiades 181 requires a high-payload equatorial mount. For reliable imaging, a mount with a rated instrument capacity of at least 60-70 lbs (27-32 kg) is strongly recommended to ensure stability and precise tracking with a full camera and guide scope setup.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes the William Optics Pleiades 181 require a separate field flattener?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. The Pleiades 181 uses an integrated \u003cstrong\u003e7-element Petzval-type design\u003c\/strong\u003e where the correcting lenses are part of the main optical assembly. It produces a natively flat \u003cstrong\u003e55mm image circle\u003c\/strong\u003e without the need for any additional flattener or reducer.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I connect my camera to the Pleiades 181 focuser?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Pleiades 181 includes a comprehensive adapter system to connect most modern astronomy cameras. The package comes with:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eM68, M54, and M48 Camera Adapters:\u003c\/strong\u003e These three common thread sizes cover the majority of dedicated astronomy cameras and filter wheels.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCamera Rotator:\u003c\/strong\u003e Allows for easy framing of your target without loosening the camera.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTilt Adjuster:\u003c\/strong\u003e Enables fine-tuning of the sensor plane to achieve perfect corner-to-corner focus.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the advantage of the Pleiades 181's 55mm image circle for 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 Pleiades 181's oversized \u003cstrong\u003e55mm image circle\u003c\/strong\u003e ensures that the entire sensor is not just illuminated, but fully corrected. This provides excellent star shapes and even brightness from the center to the extreme corners of a full-frame image, preventing vignetting and optical distortions that can appear at the edge of a smaller image circle.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan the Pleiades 181 be used for visual astronomy?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile the Pleiades 181 is optically optimized as an astrograph for imaging, it can be used visually. However, its integrated correcting lenses and focuser design may make it difficult to reach focus with some standard eyepieces and diagonals. Its primary strength and intended application is deep-sky astrophotography.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the Pleiades 181's f\/5.5 focal ratio impact 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\/5.5 focal ratio\u003c\/strong\u003e allows you to collect a significant amount of light in a shorter period compared to slower f\/8 or f\/10 systems. When imaging a large target like the Andromeda Galaxy (M31), this means you can capture the faint outer spiral arms and dust lanes with shorter individual sub-exposures, improving your signal-to-noise ratio and reducing the demands on your mount's tracking.\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\u003e7-Element Astrograph\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLens Elements\u003c\/td\u003e\n\u003ctd\u003e3x Super ED Glass\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e181 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e998 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/5.5\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\u003e4.1” Rack \u0026amp; Pinion Focuser\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Travel\u003c\/td\u003e\n\u003ctd\u003e43 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEAF Compatible\u003c\/td\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFlattener Required\u003c\/td\u003e\n\u003ctd\u003eNo, integrated design\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 (M4\/3); FUJI X\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDovetail\u003c\/td\u003e\n\u003ctd\u003eLosmandy Style\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Length (Retracted\/Extended)\u003c\/td\u003e\n\u003ctd\u003e1231 mm \/ 1496 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOTA Weight\u003c\/td\u003e\n\u003ctd\u003e15 kg \/ 33.07 lbs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTotal Weight (w\/ rings \u0026amp; dovetail)\u003c\/td\u003e\n\u003ctd\u003e18.7 kg \/ 41.23 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\"\u003ePleiades 181 Optical Tube Assembly\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\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\"\u003eCamera Angle 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 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\"\u003eM54 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\"\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\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":48603569291549,"sku":"WO-T-P-181RD","price":27597.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/FLT-180-pers-2.webp?v=1717695854"},{"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-zenithstar-81-wifd-telescope","title":"William Optics Zenithstar 81 WIFD Telescope","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003ePatented William Optics Internal Focus Design (WIFD)\u003c\/li\u003e\n\u003cli\u003eRigid M92 Rear Thread with M63 Adapter Included\u003c\/li\u003e\n\u003cli\u003eVixen\/Arca-Swiss Dual-Sided Mounting Plate\u003c\/li\u003e\n\u003cli\u003eIntegrated Handle Bar and Mounting Rings\u003c\/li\u003e\n\u003cli\u003eSoft Padded Carry Case for Transport and Storage\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\u003eDownloads\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 Zenithstar 81 WIFD Telescope\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Zenithstar 81 WIFD Telescope delivers exceptional optical stability for astrophotography by eliminating drawtube sag with its patented internal focusing mechanism. The robust rear M92 thread, which converts to M63 with the included adapter, provides a solid, flex-free connection for heavy cameras and complex imaging trains.\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 Patented WIFD: A Revolution in Internal Focusing\u003c\/h3\u003e\n\u003cp\u003eWilliam Optics' innovative Internal Focus Design (WIFD) is the centerpiece of the Zenithstar 81. Unlike traditional focusers that move an external drawtube, the WIFD moves the optics internally, ensuring the camera and other accessories remain fixed. This design completely prevents the image shift and tilt that can ruin long exposures, especially when using heavy filter wheels or off-axis guiders.\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\u003eAstrophotography-Ready Mechanics from Case to Mount\u003c\/h3\u003e\n\u003cp\u003eThis telescope is engineered for immediate use in the field. It arrives with a pre-installed dual-side mounting plate compatible with both Vixen-style and Arca-Swiss saddles, offering broad mount compatibility. The package also includes a sturdy mounting ring, a combination handle bar and guidescope saddle, and a high-quality soft carry case for safe transport to your dark-sky site.\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\u003eAn Expandable Optical System for Reducers and Guiders\u003c\/h3\u003e\n\u003cp\u003eThe Zenithstar 81 WIFD is designed as the core of a flexible imaging system. While its native optics provide sharp, high-contrast views, it is fully compatible with optional accessories like the Flat6aIII focal reducer for a wider field of view. The integrated handle bar also serves as a saddle for the optional UniGuide series of guidescopes, creating a compact and rigid platform for precise tracking during long-exposure astrophotography.\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 Zenithstar 81 WIFD's internal focuser?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe primary advantage of the \u003cstrong\u003eWilliam Optics Internal Focus Design (WIFD)\u003c\/strong\u003e is the elimination of focuser sag and tilt. By moving the optics internally and keeping the camera stationary, it provides a completely rigid imaging train that maintains perfect optical alignment, which is critical for sharp stars edge-to-edge when using heavy cameras and accessories.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Zenithstar 81 WIFD with my existing Vixen-style mount?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The Zenithstar 81 WIFD includes a dual-sided mounting plate that is compatible with both \u003cstrong\u003eVixen-style\u003c\/strong\u003e and \u003cstrong\u003eArca-Swiss\u003c\/strong\u003e saddles, allowing you to attach it to a wide variety of astronomical mounts and camera tripods without needing to purchase additional hardware.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat do I need to start guiding the Zenithstar 81 WIFD for long exposures on the Andromeda Galaxy (M31)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eTo guide the Zenithstar 81 WIFD, you will need a guidescope, such as the optional William Optics UniGuide, and a guide camera. The telescope's integrated handle bar is designed to mount a guidescope directly, creating a solid, parallel setup for accurate tracking of celestial objects like the Andromeda Galaxy (M31).\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes the Zenithstar 81 WIFD come with everything I need to attach it to a mount?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, the package includes the essential mounting hardware. It comes with a mounting ring and a dual-sided Vixen\/Arca-Swiss plate, allowing you to secure it to most common astronomical mounts right out of the box.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the internal focuser on the Zenithstar 81 WIFD handle heavy imaging trains?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe internal focuser is exceptionally well-suited for heavy imaging trains. Because the camera and accessories are threaded directly to the rigid M92 rear port of the telescope tube, their weight is not supported by a moving drawtube. This design prevents flexure, ensuring the sensor remains perfectly orthogonal to the light path regardless of the setup's weight or orientation.\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 M92 to M63 adapter for the Zenithstar 81 WIFD?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Zenithstar 81 WIFD features a large M92 native rear thread for maximum stability. The included \u003cstrong\u003eM92 to M63 adapter\u003c\/strong\u003e allows you to connect a wide range of accessories, including many field flatteners and reducers that use the more common M63 thread standard, providing greater flexibility for building your imaging train.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eAvailable Options\u003c\/td\u003e\n\u003ctd\u003eGold, Red\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\"\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\"\u003eM92→M63 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\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eNo downloads available for this product.\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":"Gold","offer_id":51292718235933,"sku":"WO-T-ZS-81GD-WIFD","price":1515.0,"currency_code":"CAD","in_stock":true},{"title":"Red","offer_id":51292718203165,"sku":"WO-T-ZS-81RD-WIFD","price":1398.0,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Z-81-WIFD-perspective-gold.jpg?v=1779207603"},{"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-telescopes.oembed","provider":"David Astro","version":"1.0","type":"link"}