{"product_id":"takahashi-toe-5-5mm-eyepiece","title":"Takahashi TOE 5.5mm Eyepiece","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe TOE 5.5 mm is a high-power planetary eyepiece from Takahashi's TOE line, built for lunar, planetary and double-star observing. It gives a 58° apparent field with 15 mm of eye relief, from six elements in four groups — more glass than a classic orthoscopic, arranged to widen the field and push the eye point back without giving up the contrast an ortho is chosen for.\u003c\/p\u003e\u003cp\u003eAt 5.5 mm it is a high-power eyepiece: the number you reach for on a night of good seeing, when a telescope's aperture and the atmosphere both support pushing magnification.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you observe planets, the Moon and double stars and want high magnification without losing the contrast that separates orthoscopic-class eyepieces from wider, more complex designs. The 58° field is moderate by wide-field standards — wide enough that a planet does not drift out of view quickly on an undriven mount, narrow enough that the design can stay well corrected at high power.\u003c\/p\u003e\u003cp\u003eIt is a visual eyepiece. Imaging trains connect a camera directly and do not use one.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e5.5 mm focal length:\u003c\/strong\u003e high power on most telescopes — see Compatibility for real figures and the practical limits at this focal length.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e58° apparent field:\u003c\/strong\u003e wider than a classic orthoscopic, with enough margin that a target stays in view for a usable interval on an undriven mount.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e15 mm eye relief:\u003c\/strong\u003e a comfortable eye position rather than the pressed-in view short-focal-length orthos demand.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSix elements in four groups:\u003c\/strong\u003e the extra elements buy field width and eye relief while holding correction across the field.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eParfocal within the TOE range:\u003c\/strong\u003e swap focal lengths mid-session with only a touch of refocusing.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003ePlanetary observing is a contrast problem before it is a resolution problem. The detail that matters — belt structure on Jupiter, the Cassini division, subtle shading on Mars — is low-contrast detail sitting on a bright disc, and scattered light inside the eyepiece raises the background and buries it. That is why the classic four-element orthoscopic held on for decades: fewer air-glass surfaces means less scatter.\u003c\/p\u003e\u003cp\u003eThe TOE design uses six elements in four groups and controls scatter directly, with multi-layer coatings and blackened element edges rather than relying on a minimal element count. The result keeps orthoscopic-class contrast while delivering a 58° field and 15 mm of eye relief — both wider than a four-element design produces at this focal length. Parfocality across the TOE range is a working convenience: changing power on a planet mid-session without hunting for focus keeps you on the target while the seeing holds.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eHigh-power planetary detail\u003c\/strong\u003e on nights of good seeing — Jupiter's belts and festoons, Saturn's rings and division, Martian surface shading.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLunar observing\u003c\/strong\u003e at close-up, crater-wall and rille detail.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDouble star splitting\u003c\/strong\u003e at the close end, where high power and clean star images matter most.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTesting a telescope's resolution\u003c\/strong\u003e on a steady night, since 5.5 mm pushes most apertures toward their practical ceiling.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMagnification:\u003c\/strong\u003e divide your telescope's focal length by 5.5. An FS-60CB at 355 mm gives about 65x; an FC-100DZ at 800 mm gives about 145x; a Mewlon 210 at 2415 mm gives about 439x — above the roughly 420x practical ceiling usually quoted for a 210 mm aperture, so that combination is a seeing-limited, best-nights eyepiece rather than an everyday one.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDiagonal:\u003c\/strong\u003e in a refractor you will normally use it behind a star diagonal. The Takahashi 1.25-inch prism diagonal is a direct pairing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eParfocal range:\u003c\/strong\u003e parfocal with the other TOE eyepieces, so changing focal length needs only a touch of refocusing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBack focus:\u003c\/strong\u003e for adapter and spacing questions across your visual train, see the \u003ca href=\"\/pages\/takahashi-back-focus-guide\"\u003eTakahashi Back Focus Guide\u003c\/a\u003e.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e5.5 mm is a high-power eyepiece, and results depend on the sky.\u003c\/strong\u003e On a smaller aperture like an FS-60CB it stays well within useful range; on a larger telescope like a Mewlon 210 it can exceed the aperture's practical magnification ceiling, and results will depend on seeing more than on the eyepiece.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThis is a visual eyepiece.\u003c\/strong\u003e Camera trains connect directly to the telescope or its corrector.\u003c\/li\u003e\n\u003c\/ul\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 a 1.25-inch diagonal or focuser and you focus. Nothing to assemble or adjust.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat magnification will I get?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYour telescope's focal length divided by 5.5. Send us your telescope model and we will work out where it fits alongside the eyepieces you already own — and whether it is within your aperture's useful range.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow does it compare to a classic orthoscopic?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eA four-element ortho at 5.5 mm gives roughly a 42° to 45° field and short eye relief. The TOE gives 58° and 15 mm of eye relief from six elements, with coatings and blackened edges doing the contrast work the simpler design got from having fewer surfaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs it good for deep-sky observing?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIt is built for high-power planetary and lunar detail rather than deep-sky work — for clusters and nebulae, a longer-focal-length, wider-field eyepiece suits better.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use it with glasses?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003e15 mm of eye relief is workable for many glasses wearers, though it depends on your frames and how far they hold the lens from your eye.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs it parfocal with my other Takahashi eyepieces?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIt is parfocal with the rest of the TOE range. Across other Takahashi families, expect to refocus.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill it work on a small telescope, or is it too much power?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eOn an FS-60CB it gives about 65x, which is a normal high-power step, not an extreme one. It is on larger apertures, closer to their magnification ceiling, that seeing becomes the limiting factor.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eIn short: a 5.5 mm planetary eyepiece with a 58° field and 15 mm of eye relief, built from six elements with the coatings and blackened edges that keep low-contrast detail visible at high power. It is the high-power step in a planetary set, most rewarding on nights when the seeing can support it.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047076909167,"sku":"TAK-TKA00616","price":480.48,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tka00616.jpg?v=1786912894","url":"https:\/\/ontariotelescope.com\/products\/takahashi-toe-5-5mm-eyepiece","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}