{"product_id":"askar-0-75x-71f-reducer","title":"Askar 0.75x 71F Reducer","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e0.75x Reduction Factor\u003c\/li\u003e\n\u003cli\u003eTransforms Askar 71F to f\/5.2\u003c\/li\u003e\n\u003cli\u003eNew Focal Length: 369mm\u003c\/li\u003e\n\u003cli\u003eStandard 55mm Back Focus\u003c\/li\u003e\n\u003cli\u003eTriplet Optical Design\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\u003eAskar 0.75x 71F Reducer\u003c\/h2\u003e\n\u003cp\u003eThe Askar 0.75x 71F Reducer transforms the Askar 71F refractor into a faster f\/5.2 imaging system with a new focal length of 369mm. This triplet reducer provides a standard 55mm back focus for easy camera integration and weighs just 0.23kg.\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 Faster Askar 71F: The 0.75x Reduction to f\/5.2\u003c\/h3\u003e\n\u003cp\u003eBy reducing the native focal ratio of the Askar 71F to f\/5.2, this corrector significantly shortens required exposure times, allowing you to gather more signal on faint targets in a single session. The resulting 369mm focal length creates a wider field of view, ideal for framing large emission nebulae like the North American Nebula (NGC 7000) or sprawling star clusters. Its triplet optical design is engineered specifically to maintain image sharpness across 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\u003eFull-Frame Correction with 55mm Standard Back Focus\u003c\/h3\u003e\n\u003cp\u003eThis reducer is also a dedicated field flattener, designed to produce sharp stars out to the corners of full-frame sensors. Imaging integration is straightforward thanks to a standard 55mm back focus, measured from the base of its M48 male thread, simplifying connection to your DSLR or dedicated astronomy camera. The design also incorporates threads for standard 2-inch filters, allowing you to use light pollution or narrowband filters without adding extra spacing to your imaging train.\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 benefit of using the Askar 0.75x Reducer with my 71F telescope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe primary benefit is speed. It reduces the focal ratio to f\/5.2, which cuts your exposure times significantly compared to the native f\/7 ratio. This allows you to collect more data on faint objects in less time.\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 Askar 71F 0.75x Reducer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe reducer provides a standard \u003cstrong\u003e55mm back focus\u003c\/strong\u003e from the base of its M48 male thread. You will need to use a combination of M48 spacers and adapters to place your camera's sensor at exactly this distance to achieve a flat field.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs this Askar 0.75x reducer suitable for imaging the Andromeda Galaxy (M31) with a full-frame camera on the 71F?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The reduced focal length of \u003cstrong\u003e369mm\u003c\/strong\u003e provides a wide field of view that is excellent for large targets like the Andromeda Galaxy (M31) or the Heart and Soul Nebulae. The reducer is designed to flatten the field for full-frame sensors, ensuring sharp stars across the entire frame.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes the Askar 0.75x 71F Reducer also work as a field flattener?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, it is a reducer-flattener. Its \u003cstrong\u003etriplet optical design\u003c\/strong\u003e corrects for field curvature, ensuring that stars are sharp from the center to the edges of the image, which is critical for astrophotography.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use 2-inch filters with the Askar 0.75x Reducer on my 71F?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The reducer's connection system is designed to accommodate standard 2-inch (M48x0.75) filters. You can thread them directly into the imaging train, making it easy to use narrowband or light pollution filters for targets like the Orion Nebula (M42).\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the image circle of the Askar 0.75x 71F Reducer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe reducer is designed as a full-frame corrector. It effectively illuminates and flattens the field for camera sensors up to a 35mm format (43mm diagonal), making it compatible with a wide range of DSLRs and dedicated astronomy cameras.\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\u003eReduction Factor\u003c\/td\u003e\n\u003ctd\u003e0.75x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eReduced Focal Length (with 71F)\u003c\/td\u003e\n\u003ctd\u003e369mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eReduced Focal Ratio (with 71F)\u003c\/td\u003e\n\u003ctd\u003ef\/5.2\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Design\u003c\/td\u003e\n\u003ctd\u003eTriplet\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBack Focus\u003c\/td\u003e\n\u003ctd\u003e55mm (from the base of M48 male thread)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRear Thread\u003c\/td\u003e\n\u003ctd\u003eM59*1\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e0.23kg\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\"\u003eAskar 0.75x 71F 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\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/www.sharpstar-optics.com\/download_list_1\/7.html\" target=\"_blank\"\u003e\u003csvg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewbox=\"0 0 640 512\" class=\"DAV-img-box\"\u003e\u003cpath fill=\"#0047a7\" d=\"M128 32C92.7 32 64 60.7 64 96l0 256 64 0 0-256 384 0 0 256 64 0 0-256c0-35.3-28.7-64-64-64L128 32zM19.2 384C8.6 384 0 392.6 0 403.2C0 445.6 34.4 480 76.8 480l486.4 0c42.4 0 76.8-34.4 76.8-76.8c0-10.6-8.6-19.2-19.2-19.2L19.2 384z\"\u003e\u003c\/path\u003e\u003c\/svg\u003e \n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDownload Software \u0026amp; Drivers\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/askar-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eAskar 1-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Askar","offers":[{"title":"Default Title","offer_id":49200895263005,"sku":"ASK-ASKAR71R","price":208.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Askar-Reducer-71F-1.jpg?v=1727375509","url":"https:\/\/davidastro.com\/fr-us\/products\/askar-0-75x-71f-reducer","provider":"David Astro","version":"1.0","type":"link"}