{"product_id":"svbony-sv109-m48-variable-extension-tube-24-35mm","title":"SVBONY SV109 M48 Variable Extension Tube 24-35mm","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eVariable Extension Range: 24mm to 35mm\u003c\/li\u003e\n\u003cli\u003eThread Type: M48x0.75 Male \u0026amp; Female\u003c\/li\u003e\n\u003cli\u003eReplaces Multiple Fixed Spacer Rings\u003c\/li\u003e\n\u003cli\u003eInternal Anti-Reflection Baffling\u003c\/li\u003e\n\u003cli\u003eLightweight Anodized Aluminum Construction\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\u003eSvbony SV109 M48 Variable Extension Tube 24-35mm\u003c\/h2\u003e\n\u003cp\u003eThe Svbony SV109 M48 Variable Extension Tube provides a continuous adjustment range from 24mm to 35mm, solving critical back focus spacing for field flatteners and focal reducers. With standard M48x0.75 threads, this single accessory replaces an entire set of fixed spacers, allowing you to precisely dial in the exact distance your imaging train requires for perfectly sharp stars.\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 24mm to 35mm of Critical Back Focus\u003c\/h3\u003e\n\u003cp\u003eGetting the spacing right for a field flattener or focal reducer is non-negotiable for sharp, round stars across your entire sensor. The Svbony SV109 replaces a whole set of fixed spacer rings with a single, adjustable unit, providing a continuous range from 24mm to 35mm. This 11mm of precise travel lets you dial in the exact back focus your optical train needs without the tedious process of unthreading and stacking different components.\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\u003eM48 Anodized Aluminum Build with Internal Baffling\u003c\/h3\u003e\n\u003cp\u003eConstructed from lightweight yet durable anodized aluminum, the SV109 maintains rigidity in your imaging setup. It features standard M48x0.75 male and female threads, ensuring broad compatibility with 2-inch format accessories like filter wheels and camera adapters. To maximize image contrast, the entire interior surface is threaded, creating an effective light baffle that traps stray reflections and prevents them from reaching your sensor.\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 main purpose of the Svbony SV109 Variable Extension Tube?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe primary purpose of the Svbony SV109 is to precisely set the distance between a field flattener or focal reducer and the camera sensor. It provides a \u003cstrong\u003e24mm to 35mm adjustable range\u003c\/strong\u003e to achieve the exact back focus required for a flat imaging field, eliminating the need for multiple fixed-length spacers.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I adjust the length of the SV109 extension tube?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYou adjust the length by twisting the two barrels of the extender. This helical mechanism provides smooth, continuous adjustment across its \u003cstrong\u003e11mm range\u003c\/strong\u003e. Once you find the correct spacing, the friction holds its position securely for your imaging session.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Svbony SV109 work with my 2-inch filters and accessories?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The SV109 uses the standard \u003cstrong\u003eM48x0.75 thread\u003c\/strong\u003e, which is the common thread size for 2-inch filters, filter wheels, off-axis guiders, and camera adapters designed for full-frame or large-sensor astronomical imaging.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy does the SV109 have internal threads?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe internal threading acts as an effective light baffle. This design scatters and absorbs any stray light that enters the tube, preventing it from causing internal reflections that can \u003cstrong\u003ereduce contrast\u003c\/strong\u003e and introduce artifacts in your astrophotos.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eMy reducer needs 55mm of back focus. Can I use the SV109 to get there from my camera's 20mm flange distance?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, this is an ideal use case. If you need 35mm of spacing (55mm total minus your camera's 20mm), you can set the SV109 to its maximum extension of \u003cstrong\u003e35mm\u003c\/strong\u003e to achieve the correct distance. This single accessory provides the exact spacing required without needing any other parts.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eI'm imaging the Andromeda Galaxy (M31) with a small refractor and a flattener. Why is the SV109 better than fixed rings?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhen imaging a large target like the Andromeda Galaxy (M31), achieving a perfectly flat field is essential. The SV109 allows for micro-adjustments in spacing (e.g., setting it to 28.5mm) that are impossible with fixed rings. This fine control lets you perfectly tune the flattener's distance for your specific telescope, ensuring \u003cstrong\u003esharp stars across the entire frame\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\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\/svbony-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eSVBONY 1-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"SVBONY","offers":[{"title":"Default Title","offer_id":52861259579677,"sku":"SV-F9180B","price":17.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/SVBONY-SV109-M48-Variable-Extension-Tube-24-35mm-for-Telescope-1_e82cc8cd-c8df-427d-a20a-47daab065457.jpg?v=1788660662","url":"https:\/\/davidastro.com\/en-us\/products\/svbony-sv109-m48-variable-extension-tube-24-35mm","provider":"David Astro","version":"1.0","type":"link"}