{"product_id":"takahashi-2-7-flattener-for-takahashi-toa-130s","title":"Takahashi TOA-35FL 2.7\" Flattener for TSA-120\/TOA-130\/TOA-150B","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe TOA-35FL is Takahashi's 2.7-inch field flattener for the TSA-120 and TOA-130\/150 triplet apochromats. It threads onto a 2-inch drawtube and presents a 2-inch female output, correcting the field to a 40mm image circle with essentially no edge distortion, at a published weight of 200 g.\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 TSA-120, TOA-130NS\/NFB, or TOA-150B and are imaging with a CCD or CMOS sensor up to full-frame, where corner star shape needs correcting that the native triplet design does not fully address on its own.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eShared across three telescopes:\u003c\/strong\u003e the same part flattens the field on the TSA-120, TOA-130NS\/NFB, and TOA-150B, each with its own resulting focal length.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e40mm corrected image circle:\u003c\/strong\u003e covers virtually all common CCD and CMOS sensor sizes without edge-of-field distortion.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e117.5mm back focus\u003c\/strong\u003e held constant across all three host telescopes.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompact 2-inch in-line design:\u003c\/strong\u003e 60mm diameter, 74mm long, 200g.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe TOA and TSA triplet apochromats are corrected for a flat visual field but benefit from a dedicated flattener when imaging across a full sensor. The TOA-35FL sits between the 2-inch drawtube and the camera train, trimming the focal length by a small, telescope-specific amount while holding the 40mm image circle and 117.5mm back focus fixed regardless of which of the three host telescopes it is mounted on.\u003c\/p\u003e\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/TKA31582_TOA-35FL_schema.png?v=1786913972\" alt=\"Dimensional diagram of the Takahashi TOA-35FL 2.7 inch Flattener\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eFull-frame and APS-C deep-sky imaging on the TSA-120, TOA-130NS\/NFB, or TOA-150B where flat corner stars are required across the sensor.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eTakahashi publishes this flattener for three telescopes.\u003c\/p\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope\u003c\/th\u003e\n\u003cth\u003eNative\u003c\/th\u003e\n\u003cth\u003eWith TOA-35FL\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\u003eTSA-120\u003c\/td\u003e\n\u003ctd\u003e900mm f\/7.5\u003c\/td\u003e\n\u003ctd\u003e880mm f\/7.3\u003c\/td\u003e\n\u003ctd\u003eΦ40mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\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\u003e980mm f\/7.5\u003c\/td\u003e\n\u003ctd\u003eΦ40mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTOA-150B\u003c\/td\u003e\n\u003ctd\u003e1100mm f\/7.3\u003c\/td\u003e\n\u003ctd\u003e1080mm f\/7.2\u003c\/td\u003e\n\u003ctd\u003eΦ40mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003cp\u003eFor sensors larger than 40mm, Takahashi's TOA-645 flattener line covers TOA-130 and TOA-150B with a 60mm image circle instead — see the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e for the full spacing picture.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003e40mm image circle, not full-format:\u003c\/strong\u003e larger sensors needing a 60mm circle should look to the TOA-645 flattener line instead of this part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eBuilt for imaging:\u003c\/strong\u003e the flattened field has no benefit for eyepiece observing, where the native triplet field is already flat enough.\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 onto the 2-inch drawtube and presents a fixed 117.5mm back focus on the camera side, 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\u003eFlat-field deep-sky imaging on the TSA-120, TOA-130NS\/NFB, or TOA-150B.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it fit sensors larger than APS-C?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIts 40mm image circle covers most full-frame sensors; for larger formats, Takahashi's TOA-645 flattener (60mm circle) is the better match — send us your sensor size and we will confirm which one you need.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the same part used on all three telescopes?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes — one flattener, with a slightly different resulting focal length on each host telescope.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe TOA-35FL is a single 2.7-inch flattener that corrects the field to a 40mm image circle at a fixed 117.5mm back focus across the TSA-120, TOA-130NS\/NFB, and TOA-150B.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047117836399,"sku":"TAK-TKA31582","price":659.23,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/TKA31582_1.jpg?v=1786914243","url":"https:\/\/ontariotelescope.com\/products\/takahashi-2-7-flattener-for-takahashi-toa-130s","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}