{"product_id":"takahashi-toa-645-flattener-0-99x-for-toa-130ns-nfb","title":"Takahashi TOA-645 Flattener 0.99x for TOA-130NS\/NFB","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe TOA-645 Flattener is Takahashi's large-format field corrector for the TOA-130NS and TOA-130NFB, holding the focal length essentially unchanged at 990mm f\/7.6 while opening the corrected image circle to 60mm — large enough for today's bigger CMOS sensors. Two lens elements in two groups thread between M72 x 1 male and female interfaces, in a compact 78mm diameter, 42mm long, 265 g housing.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you own a TOA-130NS or TOA-130NFB and are imaging with a large-format CMOS sensor where the older 67-series flatteners and the 40mm-circle TOA-35FL fall short of full corner coverage.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e60mm corrected image circle:\u003c\/strong\u003e built for large modern CMOS sensors rather than the 40mm circle of the TOA-35FL.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNear-unity focal ratio change:\u003c\/strong\u003e 1000mm f\/7.7 native becomes 990mm f\/7.6 — correction with almost no reach traded away.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTight spot diagrams:\u003c\/strong\u003e Takahashi publishes 1 micron RMS on-axis, rising to 5 microns at the full 60mm diameter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM72 x 1 threads on both sides,\u003c\/strong\u003e in a compact 78mm x 42mm housing at 265 g.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eWhere the TOA-35FL corrects the TOA-130NS\/NFB to a 40mm circle, the TOA-645 uses two lens elements in two groups to hold correction out to 60mm, addressing the larger sensor formats that have become common since the earlier 67-series flatteners were designed. Takahashi states the newer design performs nearly aberration-free with today's smaller pixel pitches, where the older flatteners show their age.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eFull-frame and medium-format CMOS deep-sky imaging on the TOA-130NS or TOA-130NFB, where corner correction across a 60mm circle is required.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eTakahashi publishes this flattener for the TOA-130NS\/NFB.\u003c\/p\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope\u003c\/th\u003e\n\u003cth\u003eNative\u003c\/th\u003e\n\u003cth\u003eWith TOA-645FL\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\u003eTOA-130NS \/ TOA-130NFB\u003c\/td\u003e\n\u003ctd\u003e1000mm f\/7.7\u003c\/td\u003e\n\u003ctd\u003e990mm f\/7.6\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\u003eThe TOA-150B takes the same optical design in a separate kit, part TKA32587S, which Ontario Telescope lists separately — the two are not interchangeable at the mechanical level despite sharing the optical formula. For smaller-sensor use, the 40mm-circle TOA-35FL is also available. Full spacing detail is in the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eNot interchangeable with the TOA-150B kit:\u003c\/strong\u003e that telescope uses its own TOA-645 flattener kit (TKA32587S) rather than this TOA-130-specific part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eBuilt for imaging:\u003c\/strong\u003e the corrected field has no benefit for eyepiece observing.\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 between M72 x 1 interfaces with a fixed 56.2mm back focus, so there is no spacing to calculate.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eFull-frame and large-format CMOS deep-sky imaging on the TOA-130NS or TOA-130NFB.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow is this different from the TOA-35FL?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThe TOA-35FL corrects a 40mm image circle; the TOA-645 corrects out to 60mm for larger sensors, at nearly the same resulting focal length.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes this fit my TOA-150B?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThe TOA-150B uses its own TOA-645 flattener kit rather than this part; send us your telescope model and sensor size and we will confirm which flattener you need.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe TOA-645 Flattener corrects the TOA-130NS\/NFB to a 60mm image circle at essentially its native 990mm f\/7.6, built for the large CMOS sensors that have outgrown the older 40mm-circle flatteners.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047124750447,"sku":"TAK-TKA31587S","price":958.1,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tka31587s-1_3.jpg?v=1786914538","url":"https:\/\/ontariotelescope.com\/products\/takahashi-toa-645-flattener-0-99x-for-toa-130ns-nfb","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}