{"product_id":"takahashi-foa-60-extender-1-7xr","title":"Takahashi FOA-60 Extender 1.7XR","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe FOA-60 Extender 1.7XR converts Takahashi's FOA-60 Ortho Apochromat to the same 900mm f\/15.0 configuration published for the dedicated FOA-60Q optical tube, with the image circle opening to 88mm and back focus extending to 208.1mm. It is built into the optical path the same way the FOA-60Q's factory objective is, rather than mounting on the drawtube as a Barlow would.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you already own the FOA-60 and want the FOA-60Q's long-focal-length performance — high-resolution lunar and planetary imaging and high-power visual observing — without buying a second optical tube.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eConverts FOA-60 to FOA-60Q spec:\u003c\/strong\u003e 530mm f\/8.8 becomes 900mm f\/15.0, matching Takahashi's own FOA-60Q tube exactly.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e88mm image circle\u003c\/strong\u003e at the extended focal length, with 208.1mm back focus.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePreserves the FOA-60's correction:\u003c\/strong\u003e Takahashi states the resulting system holds a Strehl ratio above 99% across nearly the full visible spectrum.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSupports high magnification:\u003c\/strong\u003e Takahashi rates it for visual magnifications up to 300x while keeping the image clean.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe FOA-60's 60mm fluorite doublet objective is built for correction quality over field width; the 1.7XR extender lengthens the light path to 900mm at f\/15.0 — identical to the factory FOA-60Q configuration — while the doublet's inherent correction keeps the Strehl ratio high through the extended path. This is the same route Takahashi uses to build the FOA-60Q itself, applied to an FOA-60 already in the field.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eHigh-resolution lunar and planetary imaging, and high-magnification visual observing of the Moon, planets, and double stars, on an FOA-60.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eTakahashi publishes this pairing for the FOA-60 specifically.\u003c\/p\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eTelescope\u003c\/th\u003e\n\u003cth\u003eNative\u003c\/th\u003e\n\u003cth\u003eWith EX 1.7xR\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\u003eFOA-60\u003c\/td\u003e\n\u003ctd\u003e530mm f\/8.8\u003c\/td\u003e\n\u003ctd\u003e900mm f\/15.0\u003c\/td\u003e\n\u003ctd\u003eΦ88mm\u003c\/td\u003e\n\u003ctd\u003e208.1mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003cp\u003eThe resulting figures match Takahashi's own FOA-60Q optical tube exactly. It is not combined with the FOA-60 0.93x Flattener, which serves the opposite, wide-field configuration of the same tube. See the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e for general spacing reference.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eNot combined with the 0.93x Flattener:\u003c\/strong\u003e the two accessories serve opposite configurations of the FOA-60 and are not used together.\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 installs into the optical path the same way the FOA-60Q's factory objective assembly does, with the resulting 208.1mm back focus fixed by the conversion.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eHigh-resolution lunar and planetary imaging and high-power visual observing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes this make my FOA-60 an FOA-60Q?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eOptically, yes — the resulting focal length, ratio, image circle, and back focus match Takahashi's FOA-60Q tube exactly.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I still use the FOA-60 at its native focal length afterward?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThe extender is a conversion rather than a drop-in accessory; if you want to switch back and forth between native and extended configurations, send us your setup and we will confirm what that involves.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe FOA-60 Extender 1.7XR turns an FOA-60 into the optical equivalent of Takahashi's FOA-60Q — 900mm at f\/15.0 with an 88mm image circle and 208.1mm of back focus, for high-resolution lunar and planetary work.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047122686063,"sku":"TAK-TKA28595","price":829.4,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/TKA28595_1.jpg?v=1786914498","url":"https:\/\/ontariotelescope.com\/products\/takahashi-foa-60-extender-1-7xr","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}