{"product_id":"player-one-m42f-m42m-20mm-extender","title":"Player One M42F-M42M 20mm Extender","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Player One M42F-M42M 20mm Extender is a machined aluminium spacer that adds 20 mm of length between M42 × 0.75 (T-thread) components. It carries M42 × 0.75 female threads on one end and M42 × 0.75 male threads on the other, so it threads in line without changing the thread standard. It is used to build up spacing in an M42 imaging train — typically to reach a required backfocus distance.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you are assembling an M42-threaded imaging train and need a known 20 mm step to reach the backfocus your camera, filter drawer, or corrector calls for.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFixed 20 mm spacing:\u003c\/strong\u003e adds a precise 20 mm of length in a single component.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM42 × 0.75 threads:\u003c\/strong\u003e female one end, male the other — the common T-thread \/ M42 standard.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAluminium 6061-T6:\u003c\/strong\u003e machined aluminium body, light and rigid.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMechanical only:\u003c\/strong\u003e no optical elements and no electronic connection.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBackfocus spacing:\u003c\/strong\u003e add 20 mm toward a corrector, flattener, or camera backfocus figure.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM42 train building:\u003c\/strong\u003e insert a known step between M42-threaded parts.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility \u0026amp; Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eBoth ends use the M42 × 0.75 thread standard — female on one side, male on the other. It passes the M42 thread straight through and does not convert to another standard. Backfocus is a sum of every part in the train; if you are working out how much spacing you need, send us your camera, filter, and corrector setup and we will work it out with you.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMechanical adapter only:\u003c\/strong\u003e it adds length and carries the thread — there are no optics and no electronic communication through it.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFixed length:\u003c\/strong\u003e the 20 mm step is not adjustable.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread standard:\u003c\/strong\u003e both ends are M42 × 0.75; it does not convert M42 to any other thread.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it threads directly in line between two M42 components and needs no tools or adjustment.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much length does it add?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003e20 mm.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it change the thread size?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo. Both ends are M42 × 0.75, so it keeps the M42 (T-thread) standard on both sides.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it have any optics?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo. It is a mechanical spacer with no optical elements and no electronic connection.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eIn short: a machined aluminium 20 mm spacer with M42 × 0.75 threads on both ends, made to set a known step of backfocus in an M42 imaging train.\u003c\/p\u003e","brand":"Player One Astronomy","offers":[{"title":"Default Title","offer_id":53834275815535,"sku":"M42F-M42M-20","price":33.6,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/M42F-M42M-20mm-Extender2-1024x575.png?v=1784239621","url":"https:\/\/ontariotelescope.com\/products\/player-one-m42f-m42m-20mm-extender","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}