{"product_id":"william-optics-p-flat-156","title":"William Optics Ultra Flat 156 (0.79x Reducer)","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eReduces focal ratio by a factor of 0.79x\u003c\/li\u003e\n\u003cli\u003eDesigned for Medium Format, Full Frame, and APS-C sensors\u003c\/li\u003e\n\u003cli\u003e3-element, 3-group optical design\u003c\/li\u003e\n\u003cli\u003eRequires 75.5mm of optical length (back focus)\u003c\/li\u003e\n\u003cli\u003eConnects to focusers via an M92 x 1 thread\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\u003eUltra Flat 156 (0.79x Reducer)\u003c\/h2\u003e\n\u003cp\u003eThe Ultra Flat 156 reducer shortens your telescope's focal length by a factor of 0.79x, using a 3-element, 3-group optical design to deliver wider fields of view for sensors up to Medium Format. It establishes a precise 75.5mm optical length from its M54 camera-side thread and connects to the focuser via a robust M92 x 1 thread. Weighing 1202 g (2.65 lbs), this reducer is built to support large, modern CMOS and CCD cameras without flexure.\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\u003e0.79x Reduction: Faster Imaging and Wider Fields of View\u003c\/h3\u003e\n\u003cp\u003eThis reducer transforms your telescope's imaging characteristics by reducing its effective focal length. A 0.79x reduction factor not only expands your field of view to capture larger celestial objects but also accelerates your imaging sessions. By concentrating the same amount of light onto a smaller area, it effectively makes your telescope faster, allowing you to gather more signal in less time.\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-Element Design: A Flat Field for Medium Format and Larger Sensors\u003c\/h3\u003e\n\u003cp\u003eEngineered with a 3-element optical formula arranged in 3 distinct groups, the Ultra Flat 156 is designed to deliver a flat, well-corrected image plane across very large sensors. It provides full illumination for Medium Format, Full Frame, APS-C, and M4\/3 camera formats. This ensures that you can utilize the full potential of modern, large-format astronomy cameras, achieving 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\u003eMechanical Integration: M92 Threads and 75.5mm Optical Length\u003c\/h3\u003e\n\u003cp\u003eThe Ultra Flat 156 is designed for robust, threaded connections within the imaging train. It features an M92 x 1 male thread for attachment to a compatible focuser and an M54 x 0.75 male thread on the camera side. Achieving critical focus requires a precise optical length of 75.5mm from the reducer's shoulder to the camera sensor. At 2.65 lbs (1202 g), its substantial build demands a high-capacity focuser and careful attention to mount balancing.\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 primary function of the Ultra Flat 156 reducer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Ultra Flat 156 serves two main purposes: it reduces your telescope's focal length by a factor of \u003cstrong\u003e0.79x\u003c\/strong\u003e, which provides a wider field of view, and it flattens the image plane to ensure sharp stars across large camera sensors.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat cameras are compatible with the Ultra Flat 156 reducer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis reducer is designed to illuminate a wide range of sensor sizes, including \u003cstrong\u003eMedium Format, Full Frame, APS-C, and M4\/3\u003c\/strong\u003e. It connects to the camera or filter wheel via a standard \u003cstrong\u003eM54 x 0.75\u003c\/strong\u003e male thread.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I achieve the correct 75.5mm spacing for the Ultra Flat 156?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe required \u003cstrong\u003e75.5mm optical length\u003c\/strong\u003e, or back focus, is measured from the shoulder of the reducer's M54 thread to your camera's sensor. You will need to use a combination of M54 extension rings and adapters to precisely match this distance for your specific camera setup.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat kind of telescope focuser does the Ultra Flat 156 connect to?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Ultra Flat 156 features an \u003cstrong\u003eM92 x 1\u003c\/strong\u003e male thread on the telescope side. It is designed to thread directly into a focuser drawtube with a matching M92 female thread for a secure, tilt-free connection.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eI have a full-frame camera like a ZWO ASI6200MM. Will the Ultra Flat 156 fully illuminate its sensor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The Ultra Flat 156 is specified to cover sensors up to \u003cstrong\u003eMedium Format\u003c\/strong\u003e, which is larger than the sensor in a full-frame camera. It will provide a flat, well-corrected, and fully illuminated field for your full-frame camera, ensuring no vignetting or distorted stars at the edges.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eGiven its 2.65 lbs weight, what should I consider when adding the Ultra Flat 156 to my setup?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe significant weight of \u003cstrong\u003e1202 g (2.65 lbs)\u003c\/strong\u003e requires careful consideration. First, ensure your focuser can handle the load without slipping or tilting. Second, you will need to re-balance your telescope on the mount after installing the reducer and camera to prevent tracking errors and strain on the motors.\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\u003eFlattener Power\u003c\/td\u003e\n\u003ctd\u003e0.79 x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLens Type\u003c\/td\u003e\n\u003ctd\u003e3 Groups 3 Elements\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCamera Format Compatibility\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\u003eOptical Length (Back Focus)\u003c\/td\u003e\n\u003ctd\u003e75.5 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTelescope Side Thread\u003c\/td\u003e\n\u003ctd\u003eM92 x 1 x 6.5 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCamera Side Thread\u003c\/td\u003e\n\u003ctd\u003eM54 x 0.75 x 4 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e1202 g \/ 2.65 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\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eWarranty information for this product is not available.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":52853690761501,"sku":"WO-P-FLAT-156","price":1474.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/WilliamOptics-Ultra-Flat-156-0-79x-Reducer-1_3261d2a8-0892-45a4-b3d2-bc9c9e63c550.jpg?v=1788457819","url":"https:\/\/davidastro.com\/fr\/products\/william-optics-p-flat-156","provider":"David Astro","version":"1.0","type":"link"}