{"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":2198.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/William-Optics-UltraCat-76-WIFD-1.jpg?v=1768578903","url":"https:\/\/davidastro.com\/fr-us\/products\/william-optics-ultracat-76-f-4-8-wifd","provider":"David Astro","version":"1.0","type":"link"}