{"product_id":"baader-planetarium-m54-extension-tube-5-mm","title":"Baader Planetarium M54 Extension Tube – 5 mm","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e\n\u003cstrong\u003e5 mm Fixed Extension:\u003c\/strong\u003e Adds a precise, non-flexing 5 mm of optical path length to your imaging train.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM54 Thread Standard:\u003c\/strong\u003e Connects seamlessly with M54 threaded accessories, common in full-frame imaging trains.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRigid Construction:\u003c\/strong\u003e Provides a solid, tilt-free connection that is often more stable than variable-length adapters.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInternal Baffling:\u003c\/strong\u003e Features a matte-black interior to absorb stray light and maximize image contrast.\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\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 – 5 mm\u003c\/h2\u003e\n      \u003cp\u003eThe M54 Extension Tube adds exactly 5 mm of fixed spacing to any optical train using the M54 thread standard, making it an essential component for achieving the precise back focus required by modern field flatteners and focal reducers. By filling a small gap in your imaging train, this 5 mm ring ensures your corrector-to-sensor distance is set correctly, eliminating elongated stars at the edge of the frame.\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\u003eAchieve Critical Back Focus with 5 mm of Precision Spacing\u003c\/h3\u003e\n      \u003cp\u003eMost flatteners and reducers require a specific distance to the sensor, typically 55 mm, to deliver a perfectly flat field. This 5 mm extension tube is the ideal solution for bridging the final gap when your camera and other accessories don't add up to the exact spacing needed. Its fixed-length, rigid design prevents the flexure and tilt that can compromise image quality in adjustable spacers, ensuring your optical alignment remains perfect.\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\u003eM54 Threads: A Wide 54 mm Path for Full-Frame Sensors\u003c\/h3\u003e\n        \u003cp\u003eFor imagers using full-frame or other large-format sensors, the M54 thread standard is critical for preventing vignetting. Unlike smaller M42 or M48 threads that can constrict the light cone, the larger 54 mm diameter of this extension provides an unobstructed path to the sensor. This ensures even illumination from corner to corner, preserving the faint details in wide-field targets like the Andromeda Galaxy (M31) or the North America Nebula (NGC 7000).\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\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 the M54 Extension Tube – 5 mm?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eIts primary use is to add a precise \u003cstrong\u003e5 mm\u003c\/strong\u003e of length to an M54-threaded imaging train. This is crucial for achieving the exact back focus distance (typically 55 mm) required by field flatteners, coma correctors, and focal reducers to ensure sharp, point-like 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\"\u003eWhy would I use a fixed 5 mm M54 extension tube instead of a variable spacer?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eA fixed 5 mm extension tube offers superior \u003cstrong\u003erigidity and stability\u003c\/strong\u003e. Variable spacers can sometimes introduce slight tilt or flexure into the optical train, which can degrade image quality, especially with heavy cameras. When you know you need exactly 5 mm, a fixed tube provides a more robust and reliable connection.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWill this 5 mm 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, quite the opposite. This extension uses the \u003cstrong\u003eM54 standard\u003c\/strong\u003e specifically to prevent vignetting on large sensors, including full-frame (36x24 mm) and larger formats. The wide diameter ensures the light cone from the telescope is not clipped before it reaches the sensor corners.\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 this 5 mm M54 extension tube for my imaging 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. Start with the required spacing for your flattener\/reducer (e.g., 55 mm). Then, subtract the flange distance of your camera (e.g., 17.5 mm for a ZWO camera) and the thickness of any other accessories like filter wheels or off-axis guiders. If the remaining gap is 5 mm, this extension is the perfect solution.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eCan I stack multiple 5 mm M54 extension tubes?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes, you can stack multiple extensions to achieve different lengths (e.g., two tubes for 10 mm of spacing). However, for longer distances, it is generally recommended to use a single extension of the correct length to minimize the number of threaded connections and potential for tilt.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eMy flattener requires 55 mm of back focus and my ASI camera has 17.5 mm. How does this 5 mm M54 tube help?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eIn a common ZWO imaging train, you might have a 17.5 mm camera flange, a 21 mm off-axis guider, and a 16.5 mm M48-M54 adapter, totaling 55 mm. If you replace the 16.5 mm adapter with an 11 mm version to get closer to the sensor, you create a 5.5 mm gap. This 5 mm extension tube would then be used to get you to 54.5 mm, which is often well within the tolerance for sharp stars.\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  \u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cp\u003eThis product is covered by a standard 1-year warranty against manufacturing defects.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"Default Title","offer_id":52913164124445,"sku":"BAA-2958705","price":49.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-M54-Extension-Tube-5-mm-1_8828b94c-b114-45bf-bd1c-aad173252428.jpg?v=1789086978","url":"https:\/\/davidastro.com\/fr-us\/products\/baader-planetarium-m54-extension-tube-5-mm","provider":"David Astro","version":"1.0","type":"link"}