{"product_id":"mcr0015-mewlon-cr-extender-1-5x","title":"Takahashi Mewlon CR Extender 1.5x","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Mewlon CR Extender 1.5x is Takahashi's magnifying extender for the CCA-250 and the Mewlon-250CRS and Mewlon-300CRS Cassegrains. Depending on the host telescope it stretches the native focal length by roughly 1.5x, reaching as far as f\/15.1 on the Mewlon-250CRS for high-resolution planetary and lunar work.\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 CCA-250, Mewlon-250CRS, or Mewlon-300CRS and want the longest reach those telescopes can offer — high-resolution lunar and planetary imaging, or high-power visual observing, beyond their already long native focal ratios.\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 one part, with the resulting focal length and ratio set by which Cassegrain it is mounted on.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e44mm image circle\u003c\/strong\u003e on the Mewlon-250CRS and Mewlon-300CRS; 40mm on the CCA-250.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e117.5mm back focus\u003c\/strong\u003e held constant across all three telescopes.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLong-ratio result:\u003c\/strong\u003e from f\/7.5 on the CCA-250 up to f\/15.1 on the Mewlon-250CRS.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe CCA-250, Mewlon-250CRS, and Mewlon-300CRS are already long-focus Cassegrain designs; the EX CR1.5x extends each further rather than correcting or reducing. Because the multiplier interacts with the native focal ratio of each telescope, the resulting f-ratio differs meaningfully across the line — f\/7.5 on the CCA-250's faster native f\/5.0, up to f\/15.1 on the Mewlon-250CRS's f\/10.0 — while the back focus stays fixed at 117.5mm on all three.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eHigh-resolution lunar and planetary imaging, and double-star and high-power visual observing, on the CCA-250, Mewlon-250CRS, or Mewlon-300CRS.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eTakahashi publishes this extender 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 EX CR1.5x\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\u003eCCA-250\u003c\/td\u003e\n\u003ctd\u003e1250mm f\/5.0\u003c\/td\u003e\n\u003ctd\u003e1880mm 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\u003eMewlon-250CRS\u003c\/td\u003e\n\u003ctd\u003e2500mm f\/10.0\u003c\/td\u003e\n\u003ctd\u003e3780mm f\/15.1\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMewlon-300CRS\u003c\/td\u003e\n\u003ctd\u003e2960mm f\/9.9\u003c\/td\u003e\n\u003ctd\u003e4475mm f\/14.9\u003c\/td\u003e\n\u003ctd\u003eΦ44mm\u003c\/td\u003e\n\u003ctd\u003e117.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003cp\u003eThe same three telescopes also take the companion Reducer-CR 0.73x, which Ontario Telescope carries separately, for the opposite trade-off. 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\u003eLong focal ratios reduce image brightness per unit time:\u003c\/strong\u003e f\/15.1 on the Mewlon-250CRS trades exposure speed for resolution, which suits planetary lucky-imaging more than faint deep-sky targets.\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 to the rear cell with a fixed 117.5mm back focus on all three host telescopes, so there is no spacing to work out.\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, on the CCA-250 or Mewlon CRS line.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the same part fit all three telescopes?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes — one extender, with a different resulting focal length and ratio depending on the host.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs there an opposite option for wider fields?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes — the Reducer-CR 0.73x fits the same three telescopes and reduces rather than extends; send us your target list and we can help you pick between them.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Mewlon CR Extender 1.5x stretches the CCA-250, Mewlon-250CRS, and Mewlon-300CRS to their longest published focal ratios — up to f\/15.1 — for high-resolution lunar and planetary work.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047119605871,"sku":"TAK-TKA82595","price":696.41,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tka82595_2_6.jpg?v=1786914378","url":"https:\/\/ontariotelescope.com\/products\/mcr0015-mewlon-cr-extender-1-5x","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}