{"product_id":"william-optics-p-flat-132","title":"William Optics Ultra Flat 132 (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\u003eProvides a flat field for Full Frame, APS-C, and M4\/3 sensors\u003c\/li\u003e\n\u003cli\u003e3-element, 3-group optical design\u003c\/li\u003e\n\u003cli\u003eConnects to telescope via M92 thread\u003c\/li\u003e\n\u003cli\u003eConnects to camera train via M54 thread\u003c\/li\u003e\n\u003cli\u003eWeighs 2.42 lbs (1096 g)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\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 132 (0.79x Reducer)\u003c\/h2\u003e\n\u003cp\u003eThe Ultra Flat 132 (0.79x Reducer) is the dedicated optical corrector for the William Optics Fluorostar 132, transforming the telescope into a faster, wider astrograph. This corrector provides a 0.79x focal reduction and flattens the image field for sensors up to full-frame format. Its 3-element, 3-group lens design ensures sharp stars across the entire frame, while the robust M92 telescope-side thread and 2.42 lb weight guarantee a rigid, flex-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\u003e0.79x Reduction: Transform Your FLT132 into an f\/5.45 Astrograph\u003c\/h3\u003e\n\u003cp\u003eBy applying a 0.79x reduction factor, this flattener-reducer converts the FLT132's native f\/6.9 focal ratio to a significantly faster f\/5.45. This speed increase allows you to capture the same amount of signal in nearly half the time, dramatically improving efficiency during short imaging nights. The corresponding wider field of view lets you frame large celestial targets, such as the Andromeda Galaxy (M31) or the Veil Nebula complex, in a single shot.\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, 3-Group Design: A Flat Field for Full-Frame Sensors\u003c\/h3\u003e\n\u003cp\u003eEngineered to correct for field curvature, this unit ensures your images have pinpoint stars from the center to the corners of the sensor. The 3-element, 3-group optical formula is optimized to provide a corrected image circle large enough for full-frame cameras, as well as smaller APS-C and M4\/3 formats. This eliminates the frustration of elongated stars at the edge of the field, a critical requirement for producing high-quality astrophotographs.\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\u003eM92 \u0026amp; M54 Threads: 137.5mm of Precisely Corrected Optical Path\u003c\/h3\u003e\n\u003cp\u003eThe Ultra Flat 132 ensures a secure, perfectly aligned connection to your imaging train. It attaches directly to the FLT132 focuser via a male M92 x 1 thread, preventing tilt or sag. The camera side features a standard M54 x 0.75 female thread, providing a solid interface for filter wheels, off-axis guiders, and cameras. For optimal optical correction, the total distance from the reducer's M54 shoulder to the camera sensor must be precisely set, accounting for the unit's 137.5 mm optical length.\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\u003eNative f\/6.9 vs. Reduced f\/5.45: Choosing the Right Focal Length\u003c\/h3\u003e\n\u003cp\u003eDeciding whether to image with the Ultra Flat 132 reducer depends entirely on your target. While the reducer offers significant advantages in speed and field of view, the native focal length of the telescope retains its own utility.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eNative f\/6.9 Imaging:\u003c\/strong\u003e The telescope's native focal length provides higher magnification and resolution. This is ideal for smaller targets like the Whirlpool Galaxy (M51), the Ring Nebula (M57), or planetary details where image scale is more important than field of view.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReduced f\/5.45 Imaging:\u003c\/strong\u003e The 0.79x reducer provides a wider field and cuts exposure times nearly in half. This is the clear choice for large emission nebulae like the North American Nebula (NGC 7000) or for creating mosaics of the Milky Way's core.\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 back focus is required for the Ultra Flat 132 reducer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Ultra Flat 132 reducer has a specified \u003cstrong\u003eoptical length of 137.5 mm\u003c\/strong\u003e. This is the total distance required from the reducer's M54 thread shoulder to the camera sensor for optimal field correction. You must account for the optical path length of any filters, adapters, and the camera's own internal back focus to achieve this precise spacing.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the Ultra Flat 132 compatible with telescopes other than the William Optics Fluorostar 132?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. This reducer is optically designed and mechanically threaded specifically for the William Optics Fluorostar 132 telescope. Its \u003cstrong\u003eM92 x 1 telescope thread\u003c\/strong\u003e and corrective optics are matched to that telescope's specific focal length and optical characteristics. Using it on other telescopes will not produce a corrected image.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the 0.79x reduction of the Ultra Flat 132 affect my exposure times?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e0.79x\u003c\/strong\u003e reduction makes the telescope optically faster, reducing the required exposure time for a given signal level. An f\/6.9 system becomes f\/5.45, which gathers light approximately 1.6 times faster. This means an 8-minute sub-exposure at the native focal length can be achieved in about 5 minutes with the reducer.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Ultra Flat 132 reducer fully illuminate my full-frame camera?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The Ultra Flat 132 is designed to provide a corrected and illuminated image circle that covers \u003cstrong\u003eFull Frame, APS-C, and M4\/3\u003c\/strong\u003e sensors. You can use it with large-format astronomy cameras or full-frame DSLRs\/mirrorless cameras without significant vignetting or distorted stars in the corners.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the Ultra Flat 132 reducer help when imaging the Andromeda Galaxy (M31) with an FLT132?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Andromeda Galaxy is a very large target. At the native focal length of the FLT132, you can only capture its bright core. The \u003cstrong\u003e0.79x reducer\u003c\/strong\u003e widens the field of view enough to frame the entire galaxy, including its faint outer arms and companion galaxies M32 and M110, in a single shot with a full-frame sensor.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eI'm using an M54 filter wheel with the Ultra Flat 132 reducer. How do I achieve the correct spacing?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003eM54 x 0.75\u003c\/strong\u003e camera-side thread is your starting point. You need to calculate the total length of your imaging train (filter wheel thickness, camera sensor depth, any off-axis guider) and add M54 spacers as needed to reach the total required \u003cstrong\u003e137.5 mm optical length\u003c\/strong\u003e. Remember to account for the 1\/3 optical path addition for any glass filters in the light path.\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\u003e0.79x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCamera Format\u003c\/td\u003e\n\u003ctd\u003eFull Frame, APS-C, M4\/3\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLens Design\u003c\/td\u003e\n\u003ctd\u003e3 Elements in 3 Groups\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Length\u003c\/td\u003e\n\u003ctd\u003e137.5 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTelescope Thread\u003c\/td\u003e\n\u003ctd\u003eM92 x 1 x 6.5 mm (Male)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCamera Thread\u003c\/td\u003e\n\u003ctd\u003eM54 x 0.75 x 4 mm (Female)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e1096 g \/ 2.42 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 Flat 132 (0.79x Reducer)\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":52853690695965,"sku":"WO-P-FLAT-132","price":1068.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/WilliamOptics-Ultra-Flat-132-0-79x-Reducer-1_ffef41c7-3bfa-4948-8ce7-5113ff2d4fa0.jpg?v=1788457808","url":"https:\/\/davidastro.com\/en-eu\/products\/william-optics-p-flat-132","provider":"David Astro","version":"1.0","type":"link"}