{"product_id":"baader-planetarium-m54-extension-tube-7-5-mm","title":"Baader Planetarium M54 Extension Tube – 7.5 mm","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eProvides 7.5 mm of Fixed Extension\u003c\/li\u003e\n\u003cli\u003eM54 x 0.75 Male and Female Threads\u003c\/li\u003e\n\u003cli\u003eEssential for Correcting Back Focus\u003c\/li\u003e\n\u003cli\u003eMatte Black Interior to Reduce Reflections\u003c\/li\u003e\n\u003cli\u003eMaintains Rigidity 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\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 – 7.5 mm\u003c\/h2\u003e\n      \u003cp\u003eThis M54 Extension Tube provides a fixed, non-flexing 7.5 mm of spacing, a critical component for achieving the precise back focus required by field flatteners, coma correctors, and focal reducers. It is designed for modern imaging trains that utilize the large M54 standard to connect full-frame cameras and large-format accessories without vignetting.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eAchieving Precise 7.5 mm Back Focus with M54 Threads\u003c\/h3\u003e\n      \u003cp\u003eAchieving sharp, coma-free stars from corner to corner depends entirely on setting the exact distance between your corrector lens and sensor plane. This M54 extension tube adds exactly 7.5 mm to your imaging train, allowing you to precisely dial in the required back focus. Using a fixed-length tube provides a more rigid and tilt-free connection than many variable extension systems, which is crucial for maintaining optical alignment.\u003c\/p\u003e\n      \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eM54 x 0.75 Threads:\u003c\/strong\u003e Connects seamlessly with a wide range of full-frame cameras, filter wheels, and off-axis guiders that use this large-aperture standard.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eAnti-Reflection Design:\u003c\/strong\u003e The interior is blackened and baffled to absorb stray light, preventing internal reflections from degrading image contrast.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eSolid Mechanical Connection:\u003c\/strong\u003e Machined from aluminum, this spacer ensures your camera and corrector remain perfectly parallel, preventing sensor tilt that can ruin an otherwise perfect image.\u003c\/li\u003e\n      \u003c\/ul\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n\n\u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the primary use for this M54 Extension Tube – 7.5 mm?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eIts primary purpose is to set the correct \u003cstrong\u003eback focus\u003c\/strong\u003e distance in an astrophotography imaging train. Most focal reducers and field flatteners require a specific spacing to the camera sensor (typically 55 mm), and this 7.5 mm tube is used to fill a small, precise gap to achieve that target distance.\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 7.5 mm M54 extension for my specific setup?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYou need to calculate your current back focus and compare it to what your corrector requires. Add up the optical path length of all components behind your corrector (e.g., filter wheel, off-axis guider, camera flange distance). If the total is, for example, 47.5 mm and your corrector needs 55 mm, this 7.5 mm extension tube is the perfect component to make up the difference.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eCan I stack the 7.5 mm M54 extension tube with other spacers?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes, you can stack multiple extension tubes. However, for maximum rigidity and to minimize the potential for sensor tilt, it is always best to use a single extension tube of the correct length whenever possible. Stacking several small spacers can introduce slight misalignments.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhy use a fixed 7.5 mm M54 tube instead of a variable spacer?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eA fixed extension tube like this one offers superior rigidity. Variable spacers, while flexible, can sometimes introduce a small amount of tilt or flexure into the imaging train, especially with heavier cameras. A fixed tube provides a solid, stable, and repeatable connection, which is critical for consistent, sharp results.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWill this M54 extension tube 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 thread standard is specifically designed to provide a large, clear aperture to fully illuminate full-frame sensors (36x24 mm) without vignetting. This extension tube maintains that clear aperture throughout its length, ensuring the light cone from your corrector reaches the entire sensor.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eIs the 7.5 mm M54 extension tube compatible with imaging trains on Schmidt-Cassegrain telescopes?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes, absolutely. Many focal reducers designed for SCTs, such as the Celestron f\/7 reducer for EdgeHD models, use M54 threads and require precise back focus. This extension tube is an ideal component for building out the correct spacing between the reducer and your camera.\u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\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\u003eOuter Connection (eyepiece\/-camera-sided)\u003c\/td\u003e\n\u003ctd\u003eM54 x 0.75\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInner Connection (lens sided)\u003c\/td\u003e\n\u003ctd\u003eM54 x 0.75\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\n\u003cli\u003e\n  \u003cul class=\"DAV-grid\"\u003e\n    \n  \u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"Default Title","offer_id":52913164878109,"sku":"BAA-2958707","price":49.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-M54-Extension-Tube-7-5-mm-1_e99b1d20-55b9-4b1f-a325-22ef31dfe79f.jpg?v=1789086987","url":"https:\/\/davidastro.com\/products\/baader-planetarium-m54-extension-tube-7-5-mm","provider":"David Astro","version":"1.0","type":"link"}