{"product_id":"explore-scientific-2-inch-dual-speed-rack-pinion-focuser-apo","title":"Explore Scientific 2-inch Dual-Speed Rack and Pinion Focuser for Apochromatic Refractors","description":"\u003ch2\u003eProduct Overview\u003c\/h2\u003e\u003cp\u003eThe Explore Scientific Rack \u0026amp; Pinion Focuser is a dual-speed 2-inch focuser for apochromatic refractors, combining a coarse focus knob with 10:1 micro-focusing for fine adjustment. It comes with a 1.25-inch compression ring eyepiece adapter, and three set screws hold an eyepiece, adapter or barrelled accessory securely in place. Explore Scientific publishes a weight of 2.0 lb, a 2-inch diameter and a length of 120.7 mm.\u003c\/p\u003e\u003ch2\u003eWho It's For\u003c\/h2\u003e\u003cp\u003eThis suits an observer or imager who wants finer focus control than a single-speed focuser allows. At high magnification and at fast focal ratios the depth of focus is small enough that a coarse knob overshoots; a 10:1 reduction gives you the resolution to land on best focus and stay there. It is equally useful as a replacement for a worn focuser and as an upgrade to a working but coarse one.\u003c\/p\u003e\u003ch2\u003eKey Features \u0026amp; Design\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eDual-speed operation with both a coarse focus knob and 10:1 micro-focusing knobs\u003c\/li\u003e\n\u003cli\u003eLarge knurled dials that stay easy to grip in cold weather or with gloves on\u003c\/li\u003e\n\u003cli\u003eThree set screws securing eyepieces, adapters and barrelled accessories\u003c\/li\u003e\n\u003cli\u003e1.25-inch compression ring eyepiece adapter included\u003c\/li\u003e\n\u003cli\u003e2-inch barrel accepting the full range of 2-inch eyepieces and accessories\u003c\/li\u003e\n\u003cli\u003e2.0 lb, 120.7 mm long\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eOptical and Mechanical Design\u003c\/h2\u003e\u003cp\u003eA rack-and-pinion mechanism drives the draw tube through a toothed rack, and the 10:1 reduction stage gears that motion down so a full turn of the fine knob moves the tube a tenth as far as the coarse knob would. That is the whole point at f\/6 and faster, where the range of acceptable focus is a fraction of a millimetre. The 1.25-inch adapter uses a compression ring rather than a screw pressing directly on the barrel, so eyepiece barrels are not marked or pushed off axis.\u003c\/p\u003e\u003ch2\u003eRecommended Uses\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eReplacing or upgrading the focuser on an apochromatic refractor\u003c\/li\u003e\n\u003cli\u003eHigh-magnification lunar, planetary and double star observing\u003c\/li\u003e\n\u003cli\u003eAstrophotography where focus needs to be set precisely and repeatably\u003c\/li\u003e\n\u003cli\u003eAny setup where the existing focuser is too coarse to reach best focus reliably\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eCompatibility and Accessory Notes\u003c\/h2\u003e\u003cp\u003eThis focuser is specified by Explore Scientific for their apochromatic refractors. It takes 2-inch accessories directly and 1.25-inch accessories through the included compression ring adapter. Explore Scientific also offers rack-and-pinion extension tubes if your imaging train or diagonal needs more back focus to reach a sharp image. Because focuser fit depends on the back cell of your particular telescope, send us the model and we will confirm compatibility before shipping.\u003c\/p\u003e\u003ch2\u003eGood to Know Before You Order\u003c\/h2\u003e\u003cp\u003eFit varies by telescope back cell, so a quick check with us saves a return — tell us the make and model and we will confirm. The included adapter covers 1.25-inch eyepieces, so an existing eyepiece set in either barrel size works from day one. If you reach the end of the draw tube travel without hitting focus, an extension tube is the usual remedy and we stock them.\u003c\/p\u003e\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to fit?\u003c\/strong\u003e On a matching back cell it is a hand-tool job. Confirming your telescope's back cell first is the important part, and we are happy to do that with you.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat does dual-speed actually change?\u003c\/strong\u003e The 10:1 knob moves the draw tube a tenth as far per turn as the coarse knob, so you can settle on exact focus instead of rocking back and forth past it.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use 1.25-inch eyepieces?\u003c\/strong\u003e Yes. The 1.25-inch compression ring adapter is included.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill it hold a camera?\u003c\/strong\u003e It handles a light imaging train. For a heavy cooled camera with a filter wheel on a large refractor, the 3-inch self-centering focuser is the better match at a 17 lb rating.\u003c\/p\u003e\u003ch2\u003eBottom Line\u003c\/h2\u003e\u003cp\u003eA dual-speed 2-inch focuser with 10:1 fine control, a 1.25-inch adapter in the box and knobs you can work with gloves on. A straightforward improvement in focus precision on an apochromatic refractor. Send us your telescope model and we will confirm the fit.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":53956050944111,"sku":"FOCEDAPO-RP","price":415.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/pinion_focuser_1_7e1c6252-dc40-461b-8557-dbd73c8183f1.jpg?v=1785953886","url":"https:\/\/ontariotelescope.com\/products\/explore-scientific-2-inch-dual-speed-rack-pinion-focuser-apo","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}