{"product_id":"askar-focal-plane-adjuster","title":"Askar Focal Plane Adjuster","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eCorrects focal plane tilt without altering back focus\u003c\/li\u003e\n\u003cli\u003eMaintains a constant 18mm optical thickness\u003c\/li\u003e\n\u003cli\u003eProvides a ±1° adjustment range\u003c\/li\u003e\n\u003cli\u003eFeatures M54 female front threads and M48 male rear threads\u003c\/li\u003e\n\u003cli\u003eIncludes M54 to M48 adapter for expanded compatibility\u003c\/li\u003e\n\u003cli\u003eUnique spherical adjustment mechanism for precise, simple control\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 Focal Plane Adjuster\u003c\/h2\u003e\n\u003cp\u003eThe Askar Focal Plane Adjuster corrects sensor tilt across a ±1° range using a unique spherical design that maintains a constant 18mm optical path. It connects via M54 female and M48 male threads, includes an M54-to-M48 adapter, and features 5-arcminute graduations for precise, repeatable adjustments without altering critical back 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\u003eSpherical Adjustment: Correct Tilt Without Changing Back Focus\u003c\/h3\u003e\n\u003cp\u003eSensor tilt is a primary cause of elongated stars at the edge of an image, especially with large-format cameras. Traditional push-pull adjusters can correct tilt, but the adjustment process itself often changes the distance between the corrector and sensor, disrupting the calculated back focus. The Askar Focal Plane Adjuster solves this with a unique spherical mechanism that pivots the focal plane without changing the optical path length, ensuring your back focus remains constant throughout the adjustment process.\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\u003e18mm Profile \u0026amp; M54\/M48 Threads for Seamless Compatibility\u003c\/h3\u003e\n\u003cp\u003eEngineered with a precise 18mm thickness, this adjuster is designed for easy integration into existing imaging trains. For users of specific Sharpstar and Askar telescopes (including the APO series, ASKAR V, 71F, and 50EDPH), the 18mm body directly replaces the standard M48 filter thread ring, requiring no recalculation of back focus. The unit features a female M54 front thread and a male M48 rear thread, and an included M54-to-M48 adapter ring converts the front thread for maximum compatibility with a wide range of correctors and accessories.\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\u003ePrecision Control: ±1° Range with 5' Graduations\u003c\/h3\u003e\n\u003cp\u003eAchieving a perfectly flat field requires fine control. The Askar Focal Plane Adjuster offers a ±1° tilt range, which is more than sufficient to correct for common alignment issues in focusers and camera sensors. The adjustment is made by simply rotating the handle, eliminating the need for tools or repeated disassembly of your imaging train. Laser-engraved markings at 5-arcminute intervals allow you to make deliberate, repeatable adjustments to achieve perfect star shapes across your entire 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\u003eAskar Spherical Adjuster vs. Traditional Push-Pull Designs\u003c\/h3\u003e\n\u003cp\u003eWhile three-point push-pull tilt plates are a common solution, they present a significant trade-off. Their primary disadvantage is that adjusting one screw affects the overall optical distance, forcing you to constantly re-evaluate back focus.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePush-Pull Adjusters:\u003c\/strong\u003e These require a delicate balance of loosening and tightening opposing screws. This action physically moves the camera mounting plate forward or backward, altering the precise spacing your flattener or reducer requires.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAskar Spherical Adjuster:\u003c\/strong\u003e This design pivots the entire optical assembly around a central point. The adjustment handle smoothly changes the tilt angle without any change in the front-to-back thickness, preserving your back focus and simplifying the entire process of achieving a perfectly flat imaging plane.\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\"\u003eHow does the Askar Focal Plane Adjuster work without changing back focus?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Askar Focal Plane Adjuster uses a \u003cstrong\u003eunique spherical adjustment design\u003c\/strong\u003e. Instead of pushing and pulling the mounting plate, which alters its distance, this mechanism pivots the entire assembly around a central point. This allows you to change the tilt angle by up to ±1° without affecting the 18mm optical thickness, preserving your critical back focus distance.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eMy stars are sharp in the center but elongated in one corner of my full-frame sensor. Can the Askar Focal Plane Adjuster fix this?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, this is the exact problem the Askar Focal Plane Adjuster is designed to solve. Elongated stars in the corners are a classic sign of sensor tilt, where the camera sensor is not perfectly perpendicular to the telescope's optical axis. By making small, precise adjustments with this device, you can correct the tilt and achieve sharp, round stars across the entire field of view.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eI have an Askar FRA400 refractor and a ZWO camera. How do I install the Focal Plane Adjuster?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eInstallation is straightforward. The Askar Focal Plane Adjuster has a thickness of 18mm, designed to replace the M48 filter ring at the rear of many Sharpstar\/Askar flatteners and reducers. Simply unthread the existing ring from your optical train and thread the adjuster in its place. Because the thickness is identical, your back focus calculation does not change.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat are the connection threads on the Askar Focal Plane Adjuster?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe adjuster comes with two native thread types and an adapter for flexibility:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFront (Telescope Side):\u003c\/strong\u003e Female M54x0.75 thread.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRear (Camera Side):\u003c\/strong\u003e Male M48x0.75 thread.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncluded Adapter:\u003c\/strong\u003e An M54 to M48 adapter ring is included, allowing you to convert the front M54 female thread into an M48 female thread.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDo I need any tools to use the Askar Focal Plane Adjuster?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, the Askar Focal Plane Adjuster is designed for tool-free operation. All tilt adjustments are made by simply rotating the knurled handle. This allows you to make fine corrections without disassembling your imaging train or fumbling with hex keys in the dark.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the adjustment range of the Askar Focal Plane Adjuster?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe adjuster provides a tilt adjustment range of \u003cstrong\u003e±1°\u003c\/strong\u003e. For precise and repeatable changes, the body is marked with graduations every \u003cstrong\u003e5 arcminutes\u003c\/strong\u003e (5'). This range is more than sufficient for correcting typical tilt issues found in most amateur astrophotography setups.\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\u003eOptical 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±1°\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAdjustment Scale\u003c\/td\u003e\n\u003ctd\u003e5' (arcminutes) per graduation\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFront Thread (Telescope Side)\u003c\/td\u003e\n\u003ctd\u003eM54x0.75 Female\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRear Thread (Camera Side)\u003c\/td\u003e\n\u003ctd\u003eM48x0.75 Male\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eIncluded Adapter\u003c\/td\u003e\n\u003ctd\u003eM54 Male to M48 Female (converts front thread)\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 Focal Plane Adjuster\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eM54 to M48 Adapter\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=\"#[Manual-URL]\" 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":52851346506013,"sku":"ASK-ASKARFPA","price":260.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Askar-Focal-Plane-Adjuster-1_2bd7f8a7-1e46-4eb1-a2ce-927c048d5234.jpg?v=1788401908","url":"https:\/\/davidastro.com\/fr\/products\/askar-focal-plane-adjuster","provider":"David Astro","version":"1.0","type":"link"}