{"product_id":"takahashi-toe-2-5mm-eyepiece-1-25","title":"Takahashi TOE 2.5mm Eyepiece - 1.25\"","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe TOE 2.5 mm is the shortest eyepiece in Takahashi's TOE planetary line — the one that asks the most of the telescope, the mount and the night. It gives a 52° apparent field with 10 mm of eye relief from six elements in four groups, in a 31.7 mm (1.25-inch) barrel, and weighs 145 g.\u003c\/p\u003e\u003cp\u003eTakahashi describes the TOE range as delivering performance close to the diffraction limit over the entire field of view when paired with a premium telescope. At 2.5 mm that lands at the top of almost any power range: 142x on an FS-60CB, 228x on an FC-76DCU, 320x on an FC-100DZ.\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 close double stars, and want the high end of your eyepiece set covered by a design built around contrast rather than field width. It earns its keep on the nights when the seeing settles and a shorter focal length telescope can be pushed further than usual.\u003c\/p\u003e\u003cp\u003eThe 52° field is moderate by design. At this magnification the trade is deliberate — a simpler, better-corrected field rather than an immersive one, because what limits planetary detail is scatter and contrast, not how much sky is in view.\u003c\/p\u003e\u003cp\u003eIt is a visual eyepiece. Imaging trains connect a camera directly to the telescope or its corrector 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\u003e2.5 mm focal length:\u003c\/strong\u003e the shortest in the TOE line, for the top of your power range on short and medium focal length telescopes.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e52° apparent field:\u003c\/strong\u003e moderate by intent, keeping the design simple and well corrected across the field.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e10 mm eye relief:\u003c\/strong\u003e four times the focal length, which is generous at this end of the range and makes a long session at high power comfortable.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSix elements in four groups:\u003c\/strong\u003e more glass than a classic orthoscopic, used to hold the field and the eye point without giving up correction.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e31.7 mm (1.25-inch) barrel:\u003c\/strong\u003e drops into any 1.25-inch diagonal or focuser.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e145 g:\u003c\/strong\u003e light enough that it changes nothing about focuser balance.\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. Belt structure on Jupiter, the Cassini division, shading on Mars — these are low-contrast features sitting on a bright disc, and light scattered inside the eyepiece raises the background and buries them. That is why the four-element orthoscopic held its place for so long: fewer air-glass surfaces, less scatter.\u003c\/p\u003e\u003cp\u003eThe TOE design takes six elements in four groups and spends the extra surfaces on field correction and eye relief. At 2.5 mm those are the two things a simple design struggles with most — a short orthoscopic puts the eye point almost on the glass, and its field edge softens. Ten millimetres of eye relief and a corrected 52° field are what the additional elements buy back.\u003c\/p\u003e\u003cp\u003eTakahashi lists the 2.5 mm as not parfocal, so expect to refocus when you swap it for another eyepiece rather than picking up where you left off.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlanetary detail\u003c\/strong\u003e — Jupiter's belts and festoons, Saturn's rings and division, surface shading on Mars, on nights when the seeing supports the magnification.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLunar observing\u003c\/strong\u003e — crater floors, rilles and terminator detail at high power.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eClose double stars\u003c\/strong\u003e where separation, not field width, is the whole job.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTesting and collimation checks\u003c\/strong\u003e where a high-power star image is what you are looking at.\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 2.5. An FS-60CB at 355 mm gives 142x; an FC-76DCU at 570 mm gives 228x; an FC-100DZ at 800 mm gives 320x; a TOA-130 at 1000 mm gives 400x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBarrel size:\u003c\/strong\u003e 31.7 mm (1.25-inch) — fits any 1.25-inch focuser or diagonal. The Takahashi 1.25-inch multicoated prism star diagonal is a direct pairing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFilters:\u003c\/strong\u003e standard 1.25-inch filters thread into the barrel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eParfocality:\u003c\/strong\u003e Takahashi lists this eyepiece as not parfocal, so a focal length change means a focus change.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBarlows and extenders:\u003c\/strong\u003e at 2.5 mm you are already at the short end, so this is usually the eyepiece a Barlow is not used with. If you are unsure where it sits alongside what you already own, send us your telescope and eyepiece set and we will map it out with you.\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\u003eMagnification depends entirely on your telescope.\u003c\/strong\u003e The same 2.5 mm gives 142x on a 355 mm FS-60CB and 400x on a 1000 mm TOA-130. Tell us what you are observing with and we will tell you where this lands in your set.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe sky sets the ceiling, not the eyepiece.\u003c\/strong\u003e Very high power rewards steady seeing and a well-cooled telescope. On an average night a longer TOE will show more; on a good one this is the eyepiece that pays off.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is not parfocal.\u003c\/strong\u003e Refocus after swapping — Takahashi publishes this for the 2.5 mm specifically.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e52° is a moderate field.\u003c\/strong\u003e At this power a target crosses it quickly on an undriven mount, so a tracking mount makes the eyepiece much easier to live with.\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. There is nothing to assemble, thread or space.\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 2.5. Send us your telescope model and we will work out where it fits alongside the eyepieces you already own.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs 2.5 mm too short for my telescope?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eIt depends on focal length and on your sky. On short refractors it produces a sensible high power; on long focal length telescopes it goes well past what most nights support. That is a conversation worth having before you order — send us your setup.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow does it compare to a classic orthoscopic at this focal length?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eA four-element ortho at 2.5 mm gives a narrower field and an eye point almost against the glass. The TOE uses six elements in four groups to hold a corrected 52° field with 10 mm of eye relief.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs it parfocal with my other TOE eyepieces?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eTakahashi lists the 2.5 mm as not parfocal, so plan on refocusing when you change eyepieces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use it with glasses?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eTen millimetres of eye relief is workable for some frames and tight for others. If you observe with glasses on, a longer TOE will be more comfortable.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use it for astrophotography?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — it is a visual eyepiece. Imaging trains connect the camera to the telescope or its corrector directly.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eIn short: a 2.5 mm planetary eyepiece with a 52° field, 10 mm of eye relief and six elements in four groups, in a 1.25-inch barrel. It is the top-of-the-range power in a planetary set, and it does its best work on a steady night behind a well-cooled telescope.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54070495248495,"sku":"TAK-TKA00613","price":474.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tka00613_2_5.jpg?v=1787169096","url":"https:\/\/ontariotelescope.com\/products\/takahashi-toe-2-5mm-eyepiece-1-25","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}