{"product_id":"starizona-m42-extension-7mm","title":"Starizona M42 Extension - 7mm","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eAdds 7mm of spacing\u003c\/li\u003e\n\u003cli\u003eM42 Male and Female Threads\u003c\/li\u003e\n\u003cli\u003eEssential for Correcting Back Focus\u003c\/li\u003e\n\u003cli\u003eRigid, Single-Piece 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\u003eStarizona M42 Extension - 7mm\u003c\/h2\u003e\n\u003cp\u003eThe Starizona M42 Extension adds a precise 7mm of spacing to any imaging train using standard M42 male\/female threads. This component is a simple, rigid solution for achieving the exact back focus distance required by your camera and optical corrector, ensuring your optical system performs as designed.\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\u003eAchieving 7mm of Critical Back Focus\u003c\/h3\u003e\n\u003cp\u003eEvery field flattener, coma corrector, or focal reducer has a specific, optimal distance to the camera sensor—known as back focus. Deviating from this distance can introduce image-degrading aberrations like elongated stars at the edge of the field. This 7mm extension is a fundamental tool for fine-tuning that critical spacing.\u003c\/p\u003e\n\u003cp\u003eWhen assembling your camera, filter wheel, and off-axis guider, you often end up just a few millimeters short of the ideal back focus. The Starizona M42 Extension - 7mm bridges that gap. It threads securely between any two M42 components, adding a fixed length to dial in your spacing and achieve a perfectly flat, sharp field of view from corner to corner.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\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 purpose of the Starizona M42 Extension - 7mm?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIts sole purpose is to add exactly \u003cstrong\u003e7mm\u003c\/strong\u003e of length to an M42-threaded imaging train. This is done to help achieve the precise back focus distance required by a focal reducer, field flattener, or coma corrector for optimal imaging performance.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat threads does the Starizona 7mm Extension use?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe extension uses standard \u003cstrong\u003eM42 threads\u003c\/strong\u003e. It has male threads on one side and female threads on the other, allowing it to be inserted between any two compatible M42 accessories, such as a camera T-ring and a filter wheel.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow long is this Starizona M42 extension tube?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis extension tube provides exactly \u003cstrong\u003e7mm\u003c\/strong\u003e of additional length. Starizona manufactures M42 extensions in various lengths to meet different spacing requirements.\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\u003eThread Type\u003c\/td\u003e\n\u003ctd\u003eM42 (Male\/Female)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eExtension Length\u003c\/td\u003e\n\u003ctd\u003e7mm\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\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eStarizona M42 Extension - 7mm\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\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/starizona-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eStarizona Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Starizona","offers":[{"title":"Default Title","offer_id":68045007847709,"sku":"STZ-EXTM42-7","price":6.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Starizona-M42-Extension-1_77446dd0-9c27-404d-a499-3c86be4daa13.jpg?v=1794410554","url":"https:\/\/davidastro.com\/en-int\/products\/starizona-m42-extension-7mm","provider":"David Astro","version":"1.0","type":"link"}