{"product_id":"william-optics-ad-m80-54-m48","title":"William Optics 54mm Flattener Extender for GT81 WIFD","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eProvides a precise 54mm of optical length\u003c\/li\u003e\n\u003cli\u003eConnects the FLAT68III flattener to M48 imaging trains\u003c\/li\u003e\n\u003cli\u003eDesigned specifically for the William Optics Gran Turismo 81 WIFD\u003c\/li\u003e\n\u003cli\u003eInput Thread: M80 x 0.75 female\u003c\/li\u003e\n\u003cli\u003eOutput Thread: M48 x 0.75 male\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\u003e54mm Flattener Extender for GT81 WIFD\u003c\/h2\u003e\n\u003cp\u003eThe William Optics 54mm Flattener Extender is a purpose-built adapter that provides exactly 54 mm of optical length for imagers using the GT81 WIFD telescope and FLAT68III flattener. This single component connects the flattener's M80 x 0.75 female thread to the standard M48 x 0.75 male thread of your camera or filter wheel, creating a rigid, tilt-free 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\u003eThe 54mm Spacer for FLAT68III on the GT81 WIFD\u003c\/h3\u003e\n\u003cp\u003eAchieving a perfectly flat field with the Gran Turismo 81 WIFD and FLAT68III flattener requires precise back focus. This 54mm extender is the critical component for reaching the standard 55mm back focus distance required by most astronomy cameras, with the final 1mm typically accounted for within the camera body itself. It replaces guesswork and spacer stacking with a single, correct-length solution.\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\u003eSecure M80 to M48 Threaded Connection\u003c\/h3\u003e\n\u003cp\u003eThis extender features a female M80 x 0.75 thread that securely attaches to the FLAT68III, ensuring a wide, stable connection point. The male M48 x 0.75 output thread is the universal standard for 2-inch filters and full-frame imaging accessories. By using a single, machined piece instead of multiple generic spacers, you eliminate potential sources of flexure and tilt that can degrade corner star shapes.\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 do I need this specific 54mm Flattener Extender for my GT81 WIFD?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis 54mm extender is engineered to provide the exact spacing required between the William Optics FLAT68III flattener and your camera sensor when used with the Gran Turismo 81 WIFD telescope. This ensures you achieve the specified 55mm back focus for a flat field and sharp stars corner-to-corner.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the 54mm Flattener Extender help achieve the standard 55mm back focus?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe total back focus of 55mm is a combination of this extender and the internal optical path of your camera. This adapter provides \u003cstrong\u003e54 mm\u003c\/strong\u003e of the required distance. The remaining \u003cstrong\u003e1 mm\u003c\/strong\u003e is typically the distance from the M48 thread flange on your camera to the sensor plane itself, a common specification for dedicated astronomy cameras.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the advantage of using this single 54mm Flattener Extender over stacking M48 spacers?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA single, solid extender provides a much more rigid and stable connection. Stacking multiple smaller spacers can introduce flexure or tilt into the imaging train, which can lead to elongated stars in the corners of your images. This purpose-built extender guarantees alignment and stability.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill this 54mm Flattener Extender work with my full-frame camera and 2\" filter wheel on the GT81 WIFD?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The output thread is M48 x 0.75, which is the standard for connecting to most 2\" filter wheels and full-frame camera adapters. You must ensure your total back focus, including the filter wheel and any other adapters, adds up to the required 55mm from the flattener's flange.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use this 54mm Flattener Extender with a different telescope, like a ZenithStar?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, this extender is specifically calculated for the focal length and optical design of the William Optics GT81 WIFD when paired with the FLAT68III flattener. Using it on another telescope will likely result in incorrect spacing and poor image quality, as different telescopes require different back focus distances.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat are the thread sizes for the 54mm Flattener Extender?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe extender has two threads:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eLight-In Side (attaches to flattener):\u003c\/strong\u003e M80 x 0.75 female thread\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLight-Out Side (attaches to camera):\u003c\/strong\u003e M48 x 0.75 male thread\u003c\/li\u003e\n\u003c\/ul\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 Length\u003c\/td\u003e\n\u003ctd\u003e54 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInput Thread (Flattener Side)\u003c\/td\u003e\n\u003ctd\u003eM80 x 0.75\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOutput Thread (Camera Side)\u003c\/td\u003e\n\u003ctd\u003eM48 x 0.75\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\"\u003e54mm Flattener Extender for GT81 WIFD\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":52853690859805,"sku":"WO-AD-M80-54-M48","price":68.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/WilliamOptics-54mm-Flattener-Extender-for-GT81-WIFD-1_f1df95df-d7df-4d6c-8c8d-5db8ff55af7b.jpg?v=1788457843","url":"https:\/\/davidastro.com\/en-eu\/products\/william-optics-ad-m80-54-m48","provider":"David Astro","version":"1.0","type":"link"}