{"product_id":"takahashi-tpl-50-50mm-plossl-eyepiece","title":"Takahashi TPL-50 50mm Plossl Eyepiece","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe TPL-50 is the long-focal-length end of Takahashi's TPL Plossl series — a 50 mm eyepiece with a 48° apparent field and 37 mm of eye relief, from four elements in two groups. Where the rest of the TPL range fits a standard 1.25-inch (31.7 mm) barrel, the TPL-50 uses a 2-inch (50.8 mm) barrel, the widest field stop the series offers.\u003c\/p\u003e\u003cp\u003eAt 520 g it is also the heaviest eyepiece in the line, in keeping with its larger barrel and field lens.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you already own, or are adding, a 2-inch diagonal or focuser and want the lowest power and widest true field the TPL series offers — for sweeping the Milky Way, framing large open clusters, or a comfortable wide finder-style view before switching to a higher-power eyepiece. The 37 mm eye relief is generous enough for extended sessions and most eyeglass frames.\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\u003e50 mm focal length:\u003c\/strong\u003e the lowest power and widest true field in the TPL series — see Compatibility for real figures.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e48° apparent field:\u003c\/strong\u003e the traditional Plossl field width, sharp across the center with mild softening toward the edge.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e37 mm eye relief:\u003c\/strong\u003e generous, relaxed viewing, comfortable with most glasses.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2-inch (50.8 mm) barrel:\u003c\/strong\u003e larger than the rest of the TPL range, which uses a 1.25-inch (31.7 mm) barrel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e4 elements in 2 groups:\u003c\/strong\u003e the symmetric Plossl configuration, scaled up for the longer focal length.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMulti-coated optics:\u003c\/strong\u003e 99% visible-light transmission with a matte barrel finish to control stray light.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Plossl design pairs two achromatic doublets symmetrically around the field stop — four elements in two groups. At 50 mm focal length the field lens and barrel scale up accordingly, which is why the TPL-50 moves to a 2-inch barrel where the rest of the series stays at 1.25 inches: a 48° field at this focal length needs a wider field stop than a 1.25-inch barrel can pass without vignetting.\u003c\/p\u003e\u003cp\u003eTakahashi describes the TPL series as sharp from the center out to roughly the halfway point of the 48° field, with mild star distortion toward the corners. Takahashi also states that pairing the series with the 2x Ortho Barlow clearly improves flatfieldness — though at 50 mm, doubling the focal length through a Barlow gives up most of the low-power, wide-field advantage that makes the TPL-50 worth owning in the first place.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSweeping the Milky Way and rich star fields\u003c\/strong\u003e at the lowest power your telescope can offer.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLarge open clusters and asterisms\u003c\/strong\u003e that do not fit the field of a shorter-focal-length eyepiece.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eA wide finder-style view\u003c\/strong\u003e for locating targets before switching to higher power.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRelaxed, extended viewing sessions\u003c\/strong\u003e given the 37 mm eye relief.\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 50. An FS-60CB at 355 mm gives about 7x; an FC-100DZ at 800 mm gives about 16x; a Mewlon 210 at 2415 mm gives about 48x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBarrel:\u003c\/strong\u003e 50.8 mm (2-inch) — this eyepiece needs a 2-inch diagonal or focuser. It will not fit a 1.25-inch visual back.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDiagonal:\u003c\/strong\u003e a 2-inch star diagonal or a focuser drawtube with a 2-inch visual back is required; Takahashi's 2-inch mirror diagonal is a direct pairing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e2x Ortho Barlow:\u003c\/strong\u003e Takahashi publishes that flatfieldness across the TPL series clearly improves when used through the 2x Ortho Barlow, at roughly double this eyepiece's magnification.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBack focus:\u003c\/strong\u003e for adapter and spacing questions across your imaging or 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\u003eThis is the one TPL eyepiece that needs a 2-inch diagonal or focuser.\u003c\/strong\u003e The rest of the series shares a 1.25-inch barrel; the TPL-50 does not, and a 1.25-inch visual back will not accept it.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e48° is a traditional field, not an ultra-wide one.\u003c\/strong\u003e An 82° or 100° eyepiece gives a more immersive view at the same low power; the TPL trades that width for a simpler design that still delivers a sharp center field.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMagnification depends on your telescope.\u003c\/strong\u003e The same 50 mm gives about 7x on a short 60 mm refractor and 48x on a Mewlon 210 — send us your telescope model and we will confirm where it lands in your eyepiece set.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAt 520 g, it is worth accounting for\u003c\/strong\u003e in the balance of a lighter refractor's focuser, though most Takahashi drawtubes carry it without issue.\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\u003eIt needs a 2-inch diagonal or focuser rather than the 1.25-inch fitting most eyepieces use — once that is in place, it drops in and you focus like any other eyepiece.\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 50. 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\u003eWhy does this one need a 2-inch barrel when the rest of the TPL series doesn't?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eA 48° field at 50 mm focal length needs a wider field stop than a 1.25-inch barrel can pass without vignetting, so Takahashi built the TPL-50 on a 2-inch barrel instead.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs it good for deep-sky observing?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes — it gives the widest true field and lowest power in the TPL series, suited to large clusters, asterisms and Milky Way sweeping.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use it with glasses?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003e37 mm of eye relief is comfortable for most glasses wearers.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill it work with a Barlow?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes — the 2x Ortho Barlow doubles the magnification and, per Takahashi, improves the TPL series' flatfieldness at the same time, though doing so gives up most of the low-power view this eyepiece is built for.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs it parfocal with other Takahashi eyepieces?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eSwapping to a different eyepiece family means refocusing.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eIn short: a 50 mm Plossl eyepiece with a 48° field, 37 mm of eye relief and a 2-inch barrel — the widest, lowest-power eyepiece in the TPL range, built for sweeping rich star fields once a 2-inch diagonal or focuser is in place.\u003c\/p\u003e","brand":"Takahashi","offers":[{"title":"Default Title","offer_id":54047076089967,"sku":"TAK-TKA00625","price":900.9,"currency_code":"CAD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/tka00625.jpg?v=1786912857","url":"https:\/\/ontariotelescope.com\/products\/takahashi-tpl-50-50mm-plossl-eyepiece","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}