{"product_id":"takahashi-starbase-ke-20mm-kellner-eyepiece","title":"Takahashi Starbase KE-20mm Kellner Eyepiece","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Starbase KE-20mm is a 20mm Kellner eyepiece from Takahashi's Starbase accessory line, built around a straightforward 2-groups, 3-element optical design. It delivers a 45° apparent field of view and 14mm of eye relief, and weighs 77g. It threads into any standard 1.25” focuser, diagonal, or binoviewer using the same barrel convention as the rest of the Takahashi eyepiece range.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you want a low-power, wide-field eyepiece for a Takahashi refractor or reflector — for scanning star fields, framing open clusters, or getting a bright, comfortable finder-style view before switching to higher power. It also works as a second eyepiece alongside a shorter-focal-length Starbase or TPL for a two-eyepiece kit covering low and high power.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eKellner optical design:\u003c\/strong\u003e 2 groups, 3 elements — a simple, well-corrected layout for the center and mid-field of the view.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e45° apparent field of view:\u003c\/strong\u003e a generous window at 20mm focal length, wider than the eyepieces bundled with most starter refractors.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e14mm eye relief:\u003c\/strong\u003e comfortable for observing without eyeglasses.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e77g weight:\u003c\/strong\u003e light enough not to unbalance a small refractor's focuser.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Kellner design pairs a plano-convex field lens with a cemented achromatic eye lens, a configuration that keeps cost down while holding up well at the center of the field — exactly where a low-power, wide-view eyepiece spends most of its time. At 20mm focal length and f-ratios typical of Takahashi apochromats, the KE-20mm stays undemanding on the eye and forgiving of minor eye placement, which is what the 14mm eye relief figure is doing for you.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eOn a Takahashi FS-60CB (355mm, f\/5.9) the KE-20mm gives roughly 18x — a true wide-field, grab-and-go view of large open clusters and Milky Way star fields. On a TSA-120 (900mm, f\/7.5) the same eyepiece yields about 45x, a comfortable low-power view for scanning before you move to a shorter focal length for detail. Divide any Takahashi tube's focal length by 20mm to get the magnification on your own setup.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eMost of the Starbase and Takahashi eyepiece lines use the 1.25” (31.7mm) barrel standard, which fits every Takahashi focuser, star diagonal, and 2″-to-1.25” adapter in the current catalog.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eNot parfocal with the rest of the range:\u003c\/strong\u003e expect to refocus when you swap eyepieces.\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 drops into any 1.25” focuser or diagonal and is ready to use immediately.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eLow-power, wide-field visual observing — star fields, open clusters, and framing before you switch to a shorter eyepiece for detail.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes it work for astrophotography?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIt's built for visual use. For imaging, a dedicated camera train and adapter suited to your telescope's back focus is the better route — see our \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e if you're setting one up.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat telescopes does it fit?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eAny Takahashi refractor or reflector with a standard 1.25” focuser or diagonal.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eA 20mm Kellner eyepiece with a 45° field and 14mm of eye relief — a wide, comfortable, low-power view for any Takahashi tube with a 1.25” focuser. If you're building out a full eyepiece set and want help matching focal lengths to your telescope, send us your setup and we'll work it out with you.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047072649327,"sku":"TAK-SBP08070","price":64.35,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/sbp08070_3.jpg?v=1786912635","url":"https:\/\/ontariotelescope.com\/products\/takahashi-starbase-ke-20mm-kellner-eyepiece","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}