{"title":"Askar Adapters","description":"\u003cp\u003eAskar adapters connect Askar telescopes and lenses to cameras and help set the correct backfocus in the imaging train. The M54\/M48 T-rings fit mirrorless bodies: Canon EOS-R, Sony E-mount and Nikon Z. The M54\/M48 backfocus adjuster lets you fine-tune the distance between the sensor and the corrector.\u003c\/p\u003e\u003cp\u003eAn M42-M48 photo adapter is also available for the FMA180 lens. Check the thread on the telescope side before choosing an adapter.\u003c\/p\u003e","products":[{"product_id":"askar-m54-m48-t-ring-for-canon-eos-r","title":"Askar M54\/M48 T-Ring for Canon EOS-R","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eSecurely adapts Canon EOS-R mirrorless camera bodies\u003c\/li\u003e\n\u003cli\u003eConnects to M54x0.75 and M48x0.75 threaded correctors\u003c\/li\u003e\n\u003cli\u003eIntegrated rotational adjuster for fine backfocus control\u003c\/li\u003e\n\u003cli\u003ePrecision CNC-machined for rigidity and perfect alignment\u003c\/li\u003e\n\u003cli\u003eLaser-engraved scale for repeatable spacing adjustments\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 M54\/M48 T-Ring for Canon EOS-R\u003c\/h2\u003e\n\u003cp\u003eThe Askar M54\/M48 T-Ring for Canon EOS-R provides a solid, direct-thread connection between your camera and your telescope's M54 or M48 corrector, incorporating a fine adjustment mechanism to precisely set the critical backfocus distance required for sharp stars across a full-frame sensor.\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 Canon EOS-R to M54\/M48 Connection\u003c\/h3\u003e\n\u003cp\u003eThis adapter provides a rigid, flex-free link between your Canon EOS-R camera and the large-format correctors found on modern astrographs. By threading directly to the M54 or M48 threads on your flattener or reducer, it eliminates the potential for tilt that can occur with multi-part adapter chains, ensuring your camera sensor remains perfectly orthogonal to the optical axis.\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\u003eIntegrated Backfocus Adjustment for Perfect Stars\u003c\/h3\u003e\n\u003cp\u003eAchieving the precise backfocus distance specified by your field flattener or reducer is critical for sharp stars at the edge of the frame. This Askar T-Ring features an integrated rotational adjuster that allows you to make minute changes to your sensor spacing without guesswork or stacks of shims. A laser-engraved scale provides a clear reference for repeatable results, and two locking screws secure your setting once it's dialed in perfectly.\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 Askar M54\/M48 T-Ring for Canon EOS-R used for?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis adapter connects a \u003cstrong\u003eCanon EOS-R mount mirrorless camera\u003c\/strong\u003e to a telescope's field flattener or reducer that has either \u003cstrong\u003eM54x0.75\u003c\/strong\u003e or \u003cstrong\u003eM48x0.75\u003c\/strong\u003e male threads. It also includes a built-in mechanism to make fine adjustments to the backfocus, which is the critical distance between the corrector lens and the camera sensor.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhich Askar telescopes is this Canon EOS-R adapter designed for?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis adapter is ideal for any Askar astrograph or other telescope that uses a field flattener or reducer with an M54 or M48 threaded output. It is particularly useful for full-frame imaging with refractors like the Askar FRA series or PHQ apos, ensuring a wide, unvignetted illumination of the Canon R sensor.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy is backfocus adjustment so critical when imaging with a Canon EOS-R on a refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eField flatteners and focal reducers are designed to work at a very specific distance from the camera sensor, often with a tolerance of less than a millimeter. If this distance is off, stars in the corners of your images of targets like the Pleiades (M45) will appear elongated or out of focus. This adapter's built-in adjustment allows you to precisely dial in that spacing for perfectly sharp stars across the entire full-frame sensor of your Canon EOS-R.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I use the adjustment feature on this Askar T-ring?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eTo adjust the backfocus, you first loosen the two small locking screws on the side of the adapter. You can then rotate the main body of the adapter to increase or decrease the spacing. The laser-engraved scale provides a reference for how much you have adjusted. Once you achieve perfect focus in the corners of your test images, you tighten the locking screws to fix the position.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill this adapter work with my Canon EF-mount DSLR camera?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. This adapter is specifically designed for the \u003cstrong\u003eCanon RF mount\u003c\/strong\u003e used on EOS-R series mirrorless cameras. It will not fit Canon DSLRs that use the older EF or EF-S mount.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat's the benefit of connecting to M54 threads instead of a standard M42 T-ring?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eA standard M42 T-ring has a smaller inner diameter, which can cause vignetting (darkening of the corners) on full-frame sensors like the one in a Canon EOS-R. The larger \u003cstrong\u003eM54 thread\u003c\/strong\u003e provides a wider light path, ensuring the entire sensor is fully illuminated by the corrector, which is essential for capturing clean, evenly lit wide-field images.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\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\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Askar_M54-M48_Backfocus_Adjuster_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDownload Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\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\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":46869946302749,"sku":"ASK-ASKADA54CA","price":60.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/ASK-ASKADA54CA.jpg?v=1697573160"},{"product_id":"askar-m42-m48-photo-adapter-for-fma180","title":"Askar M42-M48 Photo Adapter for FMA180","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eConnects M48 (2-inch) accessories to the Askar FMA180\u003c\/li\u003e\n\u003cli\u003eConverts the native M42x0.75 T-thread to a larger M48x0.75 thread\u003c\/li\u003e\n\u003cli\u003eEngineered for a precise fit with the FMA180 optical train\u003c\/li\u003e\n\u003cli\u003eEnables the use of full-frame camera adapters and 2-inch filter wheels\u003c\/li\u003e\n\u003cli\u003eMachined from metal for a secure, non-flexing connection\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\u003eM42-M48 Photo Adapter for FMA180\u003c\/h2\u003e\n\u003cp\u003eThis M42-M48 photo adapter is the essential component for connecting larger format imaging accessories to your Askar FMA180 astrograph. It directly converts the FMA180's standard M42x0.75 T-thread output to the wider M48x0.75 thread common on 2-inch filter wheels, filter drawers, and full-frame camera T-rings.\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\u003eM42 to M48 Conversion for the Askar FMA180\u003c\/h3\u003e\n\u003cp\u003eThe Askar FMA180's native M42 rear thread is ideal for many cameras, but it can become a bottleneck for imagers using full-frame sensors or 2-inch filter systems. This adapter solves that problem by providing a secure, correctly spaced M48 connection point, which helps minimize vignetting and allows you to integrate your existing M48 accessories into the FMA180's imaging train without compromise.\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 purpose of the M42-M48 adapter for the FMA180?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIts main function is to convert the Askar FMA180's standard M42 T-thread to a larger M48 thread. This allows you to attach accessories that use the M48 standard, such as 2-inch filter drawers or T-rings for full-frame DSLR and mirrorless cameras.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill this FMA180 adapter work with other telescopes?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, this adapter is specifically designed for the Askar FMA180. It is machined to ensure not only a correct thread fit but also to maintain the precise back focus required by the FMA180's optical design. Using a generic adapter could lead to spacing errors and degraded image quality.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat kind of accessories can I attach to my FMA180 with this adapter?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis adapter opens up compatibility with a wide range of M48-threaded accessories. Common examples include:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e2-inch Filter Wheels and Drawers:\u003c\/strong\u003e For convenient multi-filter imaging sessions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull-Frame Camera Adapters:\u003c\/strong\u003e M48 T-rings are preferred for larger sensors to reduce vignetting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOff-Axis Guiders (OAGs):\u003c\/strong\u003e Many larger OAGs use M48 threads for a more rigid connection.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes this M42-M48 adapter change the back focus of the FMA180?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis adapter is engineered to be a part of the FMA180's intended imaging train. Its optical length is factored into the system's design. You must still ensure that your camera sensor is placed at the correct back focus distance as measured from the rear flange of this adapter.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs this the same as a generic M42 to M48 step-up ring?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile it serves a similar function, it is not the same. This is a purpose-built adapter designed to integrate mechanically and optically with the Askar FMA180. A generic step-up ring may not provide the correct mechanical stability or spacing for astrophotography.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I install the M42-M48 adapter on the Askar FMA180?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eInstallation is straightforward. You typically unthread the existing M42 adapter or extension from the rear of the FMA180's focuser or optical train. Then, you carefully thread the M42-M48 adapter in its place, ensuring it is snug but not overtightened.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\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\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":52851339919645,"sku":"ASK-ASKARM4248","price":23.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Askar-M42-M48-photo-adapter-for-FMA180-1_a1088701-2d55-4de5-9520-c65b197de60a.jpg?v=1788401805"},{"product_id":"askar-backfocus-adjuster","title":"Askar M54\/M48 Backfocus Adjuster","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eProvides ±2mm of fine backfocus adjustment\u003c\/li\u003e\n\u003cli\u003eTotal optical length adjustable from 16mm to 20mm\u003c\/li\u003e\n\u003cli\u003eHigh-precision 0.05mm increments\u003c\/li\u003e\n\u003cli\u003eAvailable with M54 or M48 male camera-side threads\u003c\/li\u003e\n\u003cli\u003eCNC machined with laser-etched reference scale\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 M54\/M48 Backfocus Adjuster\u003c\/h2\u003e\n\u003cp\u003eThe Askar M54\/M48 Backfocus Adjuster provides a critical ±2mm of fine-tuning for your imaging train, allowing you to dial in spacing between 16mm and 20mm. Each increment on the laser-etched scale corresponds to a 0.05mm adjustment, ensuring you can achieve perfect star shapes across the entire frame. Available in two versions with either M54 or M48 male threads, this CNC-machined adjuster is the solution for eliminating stubborn backfocus errors.\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\u003eEliminate Spacing Errors with 0.05mm Precision Control\u003c\/h3\u003e\n\u003cp\u003ePerfect backfocus is non-negotiable for achieving sharp stars corner-to-corner, but tiny errors from filter thicknesses or manufacturing tolerances can compromise your results. This adjuster provides a total of 4mm of travel, adjustable in 0.05mm increments, allowing you to methodically find the exact spacing your flattener or reducer requires. The CNC-machined body includes a clear, printed scale for repeatable settings and two locking screw holes to fix the position once you've achieved perfect focus.\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\u003eAn M54 Input with 2 Output Options: M54 or M48\u003c\/h3\u003e\n\u003cp\u003eBoth versions of the Askar Backfocus Adjuster feature a female M54x0.75 thread on the telescope side, making them compatible with a wide range of modern correctors. The choice depends on your camera-side connection. Select the M54 male thread version for full-frame cameras and native M54 accessories, or the M48 male thread version to connect to the common 2-inch filter thread standard found on most dedicated astronomy cameras and filter wheels.\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\"\u003eHow do I use the Askar Backfocus Adjuster to find the correct spacing?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eStart with your theoretically correct backfocus distance, accounting for the adjuster's minimum 16mm length. Take a test image and examine the star shapes in the corners. Rotate the adjuster in small, \u003cstrong\u003e0.05mm increments\u003c\/strong\u003e and take new test images until the corner stars are perfectly round. Once set, use the two fixing screws to lock the position.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhich version of the Askar Backfocus Adjuster do I need?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eBoth versions accept an \u003cstrong\u003eM54x0.75 female\u003c\/strong\u003e thread from your telescope or corrector. The choice depends on the next item in your imaging train:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eM54 Version:\u003c\/strong\u003e Choose this if your camera, OAG, or filter wheel has female M54 threads.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM48 Version:\u003c\/strong\u003e Choose this if your camera or filter wheel uses the standard male M48 (2-inch filter) thread.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eMy flattener needs 55mm of backfocus, but my train is 53.5mm. Can the Askar Adjuster fix this?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, the Askar Backfocus Adjuster cannot fill a gap that large on its own. Its adjustment range is 16mm to 20mm. You would first need to add extension tubes to get close to the required 55mm, and then use the adjuster to fine-tune the final millimeter or two with its ±2mm range.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I lock the position on the Askar Backfocus Adjuster?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe adjuster features two holes for fixing screws. Once you have rotated the barrel to the desired backfocus distance, you can insert and tighten small screws (not included) into these holes to prevent any further rotation, securing your setting for the rest of your imaging session.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Askar M54 Adjuster help with elongated stars on my full-frame camera when imaging M31?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, most likely. Elongated stars in the corners of a full-frame sensor, especially on a large target like the Andromeda Galaxy (M31), are a classic sign of incorrect backfocus. The Askar M54 adjuster is ideal for this, allowing you to make tiny, precise changes to the spacing until those corner stars become sharp and round.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the minimum optical path length of the Askar Backfocus Adjuster?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe minimum optical path length added by the adjuster is \u003cstrong\u003e16mm\u003c\/strong\u003e when it is fully retracted. It can be extended up to a maximum of \u003cstrong\u003e20mm\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\u003eFront Thread (Telescope Interface)\u003c\/td\u003e\n\u003ctd\u003eM54x0.75 Female\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRear Thread (Camera Interface)\u003c\/td\u003e\n\u003ctd\u003eM54x0.75 Male or M48x0.75 Male (model dependent)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNominal Thickness\u003c\/td\u003e\n\u003ctd\u003e18mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAdjustment Range\u003c\/td\u003e\n\u003ctd\u003e±2mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTotal Optical Path\u003c\/td\u003e\n\u003ctd\u003e16mm - 20mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAdjustment Precision\u003c\/td\u003e\n\u003ctd\u003e0.05mm per increment\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eConstruction\u003c\/td\u003e\n\u003ctd\u003eCNC Machined Aluminum\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLocking Mechanism\u003c\/td\u003e\n\u003ctd\u003e2x Fixing Screw Holes\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\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Askar_M54-M48_Backfocus_Adjuster_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDownload Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eAskar M54\/M48 Backfocus Adjuster\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:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Askar_M54-M48_Backfocus_Adjuster_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDownload Manual\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":52851345326365,"sku":"ASK-ASKARBA48","price":199.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Askar-M54-M48-Backfocus-Adjuster-1_fbaf3b22-71f1-4061-807a-daaef6d9090f.jpg?v=1788401884"}],"url":"https:\/\/davidastro.com\/collections\/askar-adapters.oembed","provider":"David Astro","version":"1.0","type":"link"}