{"product_id":"takahashi-fsq-106edx4-0-72x-645rd-qe-reducer","title":"Takahashi FSQ-106EDX4 0.72x 645RD QE Reducer","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe 645RD QE 0.72x Reducer is Takahashi's medium-format focal reducer for the FSQ-106EDX4, cutting its focal length by 0.72x to reach 380mm at f\/3.6. Four large-diameter lenses deliver a Φ60mm image circle with Takahashi's published figures putting relative illumination above 70% at the periphery and above 90% across a full-frame sensor.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis reducer suits FSQ-106EDX4 owners shooting with medium-format or large full-frame cameras who want a faster focal ratio for wide, deep-sky fields — large nebula complexes, galaxy clusters, and Milky Way mosaics.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e4 lenses in 4 groups:\u003c\/strong\u003e large-diameter elements sized for a 60mm image circle.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e0.72x reduction:\u003c\/strong\u003e takes the FSQ-106EDX4 to 380mm at f\/3.6.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBroad-spectrum multilayer coatings:\u003c\/strong\u003e minimize reflections and ghosting while maximizing transmission across visible wavelengths.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM72x0.75 male input thread:\u003c\/strong\u003e installs directly on the FSQ-106EDX4's camera train.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe reducer measures 74.2mm in total length and sets a back focus of 56.2mm, matching the metal back distance published for this configuration. See the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e for the full spacing chain.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eWide-field deep-sky imaging on the FSQ-106EDX4 with medium-format or large full-frame sensors; nebula and galaxy field imaging where the full Φ60mm circle is put to use; general astrophotography where f\/3.6 shortens exposure times against the FSQ-106EDX4's native configuration.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope\u003c\/th\u003e\n\u003cth\u003eResulting focal length\u003c\/th\u003e\n\u003cth\u003eResulting focal ratio\u003c\/th\u003e\n\u003cth\u003eImage circle\u003c\/th\u003e\n\u003cth\u003eBack focus\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFSQ-106EDX4\u003c\/td\u003e\n\u003ctd\u003e380mm\u003c\/td\u003e\n\u003ctd\u003ef\/3.6\u003c\/td\u003e\n\u003ctd\u003eΦ60mm\u003c\/td\u003e\n\u003ctd\u003e56.2mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003cp\u003eThis reducer is specific to the FSQ-106EDX4 — the similarly-named 645 Reducer-CA 0.72x serves the CCA-250 instead, and the two aren't interchangeable between telescopes.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eAt 200g,\u003c\/strong\u003e it's a light addition to the imaging train, though it's worth accounting for once your camera and any filters are attached and the whole assembly is balanced on the focuser.\u003c\/p\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 onto the FSQ-106EDX4's M72x0.75 interface, and the 56.2mm back focus figure is fixed once it's installed.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eWide-field deep-sky astrophotography on the FSQ-106EDX4 with medium-format and large full-frame sensors.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it work for visual observing?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it's built to deliver a flat photographic image circle rather than a visual eyepiece path.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat else do I need with it?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYour camera's own adapter to complete the connection at the 56.2mm back focus figure.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eA medium-format 0.72x reducer that takes the FSQ-106EDX4 to 380mm at f\/3.6 across a Φ60mm image circle, at a 56.2mm back focus and a published weight of 200g.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047117508719,"sku":"TAK-TKA36580L","price":3274.7,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tka36580l_2_6.jpg?v=1786914208","url":"https:\/\/ontariotelescope.com\/products\/takahashi-fsq-106edx4-0-72x-645rd-qe-reducer","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}