{"product_id":"televue-ethos-sx-3-7mm-110-eyepiece","title":"TeleVue Ethos-SX 3.7mm 110° Eyepiece - 1.25\"\/2\"","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e3.7mm Focal Length\u003c\/li\u003e\n\u003cli\u003e110° Apparent Field of View\u003c\/li\u003e\n\u003cli\u003e2\" \/ 1.25\" Hybrid Barrel\u003c\/li\u003e\n\u003cli\u003e15mm Eye Relief\u003c\/li\u003e\n\u003cli\u003e7.0mm Field Stop\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eTeleVue Ethos 3.7mm SX 110° Eyepiece - 2\" \/ 1.25\"\u003c\/h2\u003e\n\u003cp\u003eThe Tele Vue Ethos 3.7mm SX (Super eXtended) is the ultimate high-magnification specialist in the Ethos line. While most wide-field eyepieces sacrifice field of view as focal lengths get shorter, the 3.7mm SX does the opposite—expanding to a massive 110° Apparent Field of View. This provides 21 percent more viewing area than a 100° eyepiece, creating an unparalleled \"spacewalk\" experience even at the extreme magnifications required for the finest celestial details.\u003c\/p\u003e\n\u003cp\u003eThis eyepiece is engineered for the most demanding visual tasks. In most telescopes, the 3.7mm focal length pushes the limits of atmospheric seeing, making it a \"treasure hunter\" tool for those nights of perfect stability. The 7.0mm field stop is meticulously optimized to deliver maximum contrast, allowing you to resolve the tiniest features on the lunar surface or separate the closest double stars that other eyepieces might merge into a single blur.\u003c\/p\u003e\n\u003cp\u003eThe 110° field is a functional necessity at this power level. By providing such a vast window, the 3.7mm SX allows objects to remain in the field of view significantly longer in non-tracking telescopes, giving your eye the time it needs to wait for those moments of perfect clarity. It is parfocal with the 4.7mm Ethos SX, making it easy to swap when you need that final jump in resolution.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eThe Ultimate High-Resolution Tool\u003c\/h3\u003e\n\u003cp\u003eAt 3.7mm, you are accessing the top tier of your telescope's resolving power. The 110° field removes the \"tunnel vision\" usually felt at these magnifications, replacing it with an immersive vista that keeps you oriented within the star field.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eLunar Prowess:\u003c\/strong\u003e Perfect for high-power exploration of rilles, dome structures, and the central peaks of craters like Tycho or Aristarchus.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDouble Star Specialist:\u003c\/strong\u003e The extreme magnification and 110° field make it easier to split tight doubles while still seeing the surrounding star field for context.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompact Deep Sky:\u003c\/strong\u003e Ideal for magnifying small planetary nebulae or the cores of globular clusters, where the tiny 0.3mm to 0.5mm exit pupil (depending on your scope) provides an inky black sky background.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThis eyepiece excels in short focal length refractors and fast Newtonians, where it provides high resolution without the magnification becoming unusable due to atmospheric turbulence.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eAtmospheric Limits and Performance\u003c\/h3\u003e\n\u003cp\u003eThe 3.7mm Ethos SX is a performance-first optic. Because it generates such high magnification, its performance is closely tied to the quality of your night sky. On nights of average seeing, the view may appear \"soft\" due to the atmosphere; however, on steady nights, this eyepiece will reveal details you simply cannot see with longer focal lengths.\u003c\/p\u003e\n\u003cp\u003eFor observers with large, fast Dobsonians, the 3.7mm SX often becomes the go-to choice for pushing the limits of the mirror's resolution. It provides the \"drift time\" necessary to observe comfortably without the constant, frantic nudging required by narrower 50° or 60° planetary eyepieces.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eHybrid Mounting and Professional Build\u003c\/h3\u003e\n\u003cp\u003eThe 3.7mm SX features the Tele Vue hybrid 2\" \/ 1.25\" barrel, ensuring it fits into almost any high-quality focuser or diagonal. To maintain the highest possible contrast at these power levels, Tele Vue utilizes advanced multi-coatings and internal baffling to eliminate stray light and ghosting.\u003c\/p\u003e\n\u003cp\u003eIn fast Newtonian systems (f\/4.5 or faster), using a Tele Vue Paracorr Type 2 is highly recommended. This ensures that the stars remain pinpoint sharp across the entire 110° field, allowing you to utilize every millimeter of that massive field stop for high-resolution observation.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat makes the 3.7mm \"SX\"?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eSX stands for Super eXtended. It refers to the 110° apparent field of view, which is a 10° increase over the standard Ethos series, providing a 21 percent larger viewing area.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs 3.7mm too much magnification for my telescope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIn a long focal length telescope like an 8\" f\/10 SCT, 3.7mm produces over 500x magnification, which is rarely usable. It is best suited for refractors (like an NP101) or fast reflectors (f\/4 to f\/5) where it provides a practical high-power range of 150x to 300x.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy use a 110° field for high power?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAt high magnification, objects move across the field very quickly. The 110° field gives you significantly more \"drift time,\" meaning you spend more time observing the object and less time manually tracking or nudging your telescope.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the 3.7mm Ethos with glasses?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe eyepiece has 15mm of eye relief. While some eyeglass wearers may find it tight to see the full 110° field, the 3.7mm SX is fully compatible with Tele Vue Dioptrx for correcting astigmatism without needing glasses.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the 3.7mm Ethos SX parfocal with others?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt is parfocal with the 4.7mm Ethos SX. When switching from other Ethos focal lengths like the 13mm or 8mm, a very small focus adjustment may be required.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eModel #\u003c\/td\u003e\n\u003ctd\u003eETH-03.7\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e3.7 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBarrel Size\u003c\/td\u003e\n\u003ctd\u003e2\" \/ 1.25\" Hybrid\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApparent Field of View\u003c\/td\u003e\n\u003ctd\u003e110°\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEye Relief\u003c\/td\u003e\n\u003ctd\u003e15 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eField Stop Diameter\u003c\/td\u003e\n\u003ctd\u003e7.0 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e1.1 lb (17.6 oz \/ 500 g)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFilter Compatibility\u003c\/td\u003e\n\u003ctd\u003eThreaded for 1.25\" and 2\" Filters\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDimensions\u003c\/td\u003e\n\u003ctd\u003e53.3 x 147 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cimg class=\"DAV-img-box\" alt=\"Ethos 3.7mm SX Eyepiece\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/TeleVue-Ethos-SX-3_7mm-Eyepiece-1.jpg?v=1775102497\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eEthos 3.7mm SX Eyepiece\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cimg class=\"DAV-img-box\" alt=\"Dust Cap\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/TeleVue-2inch-Dustcap.jpg?v=1774403118\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDust Cap (Top)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cimg class=\"DAV-img-box\" alt=\"Dust Cap\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/TeleVue-2inch-Dustcap.jpg?v=1774403118\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDust Cap (Bottom)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/TeleVue-Ethos-SX-Eyepieces-Manual.pdf?v=1775101962\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDownload Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/davidastro.com\/pages\/televue-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003e Tele Vue 5-Year Limited Warranty for Telescopes and Accessories \u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"TeleVue","offers":[{"title":"Default Title","offer_id":51110750388509,"sku":"TV-ETH-03.7","price":1043.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/TeleVue-Ethos-SX-3_7mm-Eyepiece-1.jpg?v=1775102497","url":"https:\/\/davidastro.com\/products\/televue-ethos-sx-3-7mm-110-eyepiece","provider":"David Astro","version":"1.0","type":"link"}