{"product_id":"baader-planetarium-m54-extension-tube-40-mm","title":"Baader Planetarium M54 Extension Tube – 40 mm","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eProvides 40mm of fixed extension\u003c\/li\u003e\n\u003cli\u003eStandard M54 x 0.75 threads\u003c\/li\u003e\n\u003cli\u003eMale and female threads for easy integration\u003c\/li\u003e\n\u003cli\u003eRigid design prevents flexure in the imaging train\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\u003eM54 Extension Tube – 40 mm\u003c\/h2\u003e\n\u003cp\u003eThis M54 Extension Tube provides a fixed, non-flexing 40mm of spacing, essential for setting the correct back focus in a threaded imaging train. Designed for M54 accessories, it ensures your flattener or reducer is positioned at the precise distance required for a flat field from edge to edge.\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\u003eAchieve Precise 40mm Back Focus with M54 Threads\u003c\/h3\u003e\n\u003cp\u003eAchieving the manufacturer-specified back focus is critical for astrophotography, and this 40mm extension tube is a simple, rigid solution for hitting that mark. It features male M54 threads on one side and female on the other, allowing it to connect seamlessly between your camera, filter wheel, or off-axis guider.\u003c\/p\u003e\n\u003cp\u003eThe M54 thread standard provides a large, robust connection that prevents both vignetting on larger sensors and flexure that can tilt your camera sensor. This single 40mm tube is often a more stable solution than stacking multiple smaller extensions, which can introduce potential points of tilt or rotation.\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 M54 Extension Tube – 40 mm primarily used for?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis extension tube is used to add exactly \u003cstrong\u003e40mm of length\u003c\/strong\u003e to an M54-threaded imaging train. Its primary purpose is to help achieve the precise back focus distance required by optical correctors like field flatteners and focal reducers, ensuring sharp stars across the entire sensor.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I know if I need a 40mm extension for my imaging setup?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYou need to calculate the total back focus required by your flattener or reducer (typically 55mm, but check your specific model) and then subtract the back focus consumed by your camera, off-axis guider, and filter wheel. If the remaining distance needed is 40mm, this extension is the correct component.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eAre the threads on this 40mm M54 tube male or female?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eLike most extension tubes, this component has \u003cstrong\u003emale M54 threads on one end and female M54 threads on the other\u003c\/strong\u003e. This allows it to be inserted between two other M54 accessories, such as connecting a flattener to a filter wheel.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I stack this 40mm M54 tube with other extensions?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, you can stack this with other M54 extensions to achieve a custom length. However, for maximum stability and to minimize potential tilt, it is always best to use a single extension tube that is as close as possible to your required distance.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill this 40mm M54 extension cause vignetting with my full-frame camera?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. The M54 standard (54mm diameter) is specifically designed to provide a large, unvignetted light path for full-frame sensors (42mm diagonal) and even some larger formats. This extension will not be the limiting factor for illumination in a properly designed full-frame imaging train.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the thread pitch of the M54 threads on this 40mm extension?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile not specified, the standard thread pitch for M54 accessories in astronomy is \u003cstrong\u003e0.75mm (M54x0.75)\u003c\/strong\u003e. This extension is designed to be compatible with equipment from major brands that use this common standard.\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\u003eLength\u003c\/td\u003e\n\u003ctd\u003e40 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThread Type\u003c\/td\u003e\n\u003ctd\u003eM54 x 0.75\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.01 (5 mm, 7.5 mm, 10 mm)\u003cbr\u003e0.02 (15 mm)\u003cbr\u003e0.04 (30 mm)\u003cbr\u003e0.05 (40 mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInner Diameter \/ Clear Aperture (mm)\u003c\/td\u003e\n\u003ctd\u003e51 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOuter Diameter\u003c\/td\u003e\n\u003ctd\u003e59 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eType of Adapter\u003c\/td\u003e\n\u003ctd\u003eExtension\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical length (mm)\u003c\/td\u003e\n\u003ctd\u003e5 (5 mm)\u003cbr\u003e7.5 (7.5 mm)\u003cbr\u003e10 (10 mm)\u003cbr\u003e15 (15 mm)\u003cbr\u003e30 (30 mm)\u003cbr\u003e40 (40 mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAdapters Family\u003c\/td\u003e\n\u003ctd\u003eM54 System\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\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"Default Title","offer_id":52913168744733,"sku":"BAA-2958740","price":59.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-M54-Extension-Tube-40-mm-1_1e5d5d64-c3c9-44c5-a683-935ab5036ef5.jpg?v=1789087021","url":"https:\/\/davidastro.com\/fr-us\/products\/baader-planetarium-m54-extension-tube-40-mm","provider":"David Astro","version":"1.0","type":"link"}