{"product_id":"takahashi-starbase-or-18mm-orthoscopic-eyepiece","title":"Takahashi Starbase OR-18mm Orthoscopic Eyepiece","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Starbase OR-18mm is an 18mm orthoscopic eyepiece from Takahashi's Starbase accessory line, built on a 4-elements-in-2-groups design that keeps distortion low, particularly toward the center of the field. It has a 45° apparent field of view, 13mm of eye relief, and a 1.25” (31.7mm) barrel that fits standard Takahashi focusers and diagonals. Optical coatings are fully multi-coated throughout.\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 sharp, low-distortion eyepiece at a moderate focal length — for lunar terrain, double stars, and planetary detail on nights when a mid-power view suits the seeing better than the highest-power eyepiece in your case.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eOrthoscopic 4-element, 2-group design:\u003c\/strong\u003e favors low distortion and center sharpness over the widest possible field.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e45° apparent field of view:\u003c\/strong\u003e a moderate window that keeps the target centered without much drifting during unguided visual sessions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e13mm eye relief:\u003c\/strong\u003e workable for observers who wear glasses.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFully multi-coated optics:\u003c\/strong\u003e reduces internal reflections and improves contrast.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.25” (31.7mm) barrel:\u003c\/strong\u003e the Takahashi standard, fits existing focusers and diagonals without an adapter.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical \/ Mechanical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eOrthoscopic eyepieces trade field width for correction at the center of the view — the four-element, two-group layout used here is chosen specifically to hold that correction with low distortion, which is why orthoscopics remain a common choice for high-contrast planetary and lunar observing even though wider-field designs have become more common elsewhere in the eyepiece market. At 18mm, the OR-18mm sits toward the low-power end of the Starbase orthoscopic range.\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 OR-18mm gives about 20x, a comfortable low-power view for star fields and lunar overviews. On a TSA-120 (900mm, f\/7.5) the same eyepiece yields roughly 50x — a solid all-purpose magnification for the Moon, brighter planets, and double stars. Divide any Takahashi tube's focal length by 18mm for the magnification on your own setup.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe 1.25” (31.7mm) barrel fits any Takahashi focuser, star diagonal, or 2″-to-1.25” adapter already in the current lineup, so it slots into an existing eyepiece case without any extra hardware.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eNot parfocal:\u003c\/strong\u003e Takahashi lists this eyepiece as non-parfocal, so a small refocus is needed when you switch to it from another eyepiece.\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 directly into a 1.25” focuser or diagonal.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is it best used for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eModerate-power visual observing — lunar detail, double stars, and planets, with the low-distortion correction orthoscopic designs are known for.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow does it differ from the Starbase KE eyepieces?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThe KE (Kellner) eyepieces use a simpler 3-element design and lean toward wider, lower-power views; the OR (orthoscopic) eyepieces use a 4-element design tuned for sharper, more distortion-free images at the center of the field.\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\u003eAn 18mm orthoscopic eyepiece with a 45° field, 13mm eye relief, and the standard 1.25” barrel — a sharp, moderate-power choice for lunar and planetary detail. If you're putting together 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":54047073304687,"sku":"TAK-SBP08050","price":70.07,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/sbp08050_3.jpg?v=1786912668","url":"https:\/\/ontariotelescope.com\/products\/takahashi-starbase-or-18mm-orthoscopic-eyepiece","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}