{"product_id":"explore-scientific-72-ed-20mm-eyepiece","title":"Explore Scientific 72° ED Series 20mm Waterproof Eyepiece (1.25\")","description":"\u003ch2\u003eWide, low-power views in a 1.25-inch eyepiece\u003c\/h2\u003e\n\u003cp\u003eThe \u003cstrong\u003eExplore Scientific 72° ED Series 20mm Waterproof Eyepiece\u003c\/strong\u003e is a low-to-mid power wide-field eyepiece for scanning the sky and taking in large objects whole. It has a 72° apparent field, a 1.25\" barrel, 15mm of eye relief and a 24.8mm field stop, and its optics include H-FK61 ED glass to keep color fringing low and contrast high. Explore Scientific builds the series to be waterproof, and this eyepiece weighs 330g (11.6oz).\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eKey specs:\u003c\/strong\u003e 20mm focal length · 72° apparent field · 1.25\" barrel · 15mm eye relief · 24.8mm field stop · 6 elements in 4 groups · H-FK61 ED glass · waterproof · 330g (11.6oz)\u003c\/p\u003e\n\u003ch2\u003eWhat you'll see\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe whole Moon\u003c\/strong\u003e with space around it in most telescopes.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLarge nebulae and galaxies:\u003c\/strong\u003e the Orion Nebula with its outer wings, the core of the Andromeda Galaxy with M32, and the Lagoon and Trifid Nebulae together in shorter telescopes.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStar clusters:\u003c\/strong\u003e the Double Cluster, the Beehive Cluster and M35 with NGC 2158.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eIn an \u003ca href=\"\/products\/sky-watcher-8-inch-traditional-dobsonian\"\u003e8\" Dobsonian\u003c\/a\u003e (1200mm) the 20mm gives 60x and a 1.18° true field. In an 80mm f\/6 refractor (480mm) it gives 24x and a 2.96° field. For comparison, the full Moon is about 0.5° across.\u003c\/p\u003e\n\u003ch2\u003eWhy the 72° ED series\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eWide without the bulk:\u003c\/strong\u003e 72° is wide enough to frame objects with plenty of sky around them, while keeping the eyepiece smaller and lighter than 82° and 100° designs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eED glass:\u003c\/strong\u003e an H-FK61 fluorophosphate element (Abbe number 81.6) reduces color fringing on bright stars, the Moon and planets. Coatings are multi-layer.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e15mm eye relief:\u003c\/strong\u003e comfortable without glasses, and usable with them by many observers.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWaterproof:\u003c\/strong\u003e dew and damp nights are less of a worry, and the eyepiece is easier to keep clean.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eWhat to add for the best results\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eA good diagonal:\u003c\/strong\u003e for refractors and Schmidt-Cassegrains, the \u003ca href=\"\/products\/celestron-dielectric-star-diagonal-1-25-wiith-twist-lock\"\u003eCelestron 1.25\" Dielectric Star Diagonal\u003c\/a\u003e has a twist-lock that holds the eyepiece securely.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eA Barlow:\u003c\/strong\u003e the \u003ca href=\"\/products\/celestron-2x-1-25-omni-barlow-lens\"\u003eCelestron 2x Omni Barlow\u003c\/a\u003e doubles the magnification, turning this eyepiece into an effective 10mm.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMore of the series:\u003c\/strong\u003e pair it with the \u003ca href=\"\/products\/explore-scientific-72-ed-25mm-eyepiece\"\u003e25mm\u003c\/a\u003e and \u003ca href=\"\/products\/explore-scientific-72-ed-15mm-eyepiece\"\u003e15mm\u003c\/a\u003e for a matched set with the same 72° field and feel.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eWhich 72° ED eyepiece is right for you?\u003c\/h2\u003e\u003ctable\u003e\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal length\u003c\/th\u003e\n\u003cth\u003eBarrel\u003c\/th\u003e\n\u003cth\u003eEye relief\u003c\/th\u003e\n\u003cth\u003eField stop\u003c\/th\u003e\n\u003cth\u003ePower \/ field in an 8\" Dob\u003c\/th\u003e\n\u003cth\u003eBest for\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/explore-scientific-72-ed-6-5mm-eyepiece\"\u003e6.5mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003ctd\u003e18mm\u003c\/td\u003e\n\u003ctd\u003e8mm\u003c\/td\u003e\n\u003ctd\u003e185x \/ 0.38°\u003c\/td\u003e\n\u003ctd\u003ePlanets, the Moon and double stars\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/explore-scientific-72-ed-8-5mm-eyepiece\"\u003e8.5mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003ctd\u003e18mm\u003c\/td\u003e\n\u003ctd\u003e10.5mm\u003c\/td\u003e\n\u003ctd\u003e141x \/ 0.50°\u003c\/td\u003e\n\u003ctd\u003ePlanets on typical nights, globulars\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/explore-scientific-72-ed-11-5mm-eyepiece\"\u003e11.5mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003ctd\u003e18mm\u003c\/td\u003e\n\u003ctd\u003e14.4mm\u003c\/td\u003e\n\u003ctd\u003e104x \/ 0.69°\u003c\/td\u003e\n\u003ctd\u003eMedium power for globulars, galaxies and the Moon\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/explore-scientific-72-ed-15mm-eyepiece\"\u003e15mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003ctd\u003e18mm\u003c\/td\u003e\n\u003ctd\u003e18.5mm\u003c\/td\u003e\n\u003ctd\u003e80x \/ 0.88°\u003c\/td\u003e\n\u003ctd\u003eOpen clusters and nebulae\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003e20mm\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003ctd\u003e15mm\u003c\/td\u003e\n\u003ctd\u003e24.8mm\u003c\/td\u003e\n\u003ctd\u003e60x \/ 1.18°\u003c\/td\u003e\n\u003ctd\u003eLow power in a 1.25\" focuser; finding and framing\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/explore-scientific-72-ed-25mm-eyepiece\"\u003e25mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e2\"\u003c\/td\u003e\n\u003ctd\u003e18mm\u003c\/td\u003e\n\u003ctd\u003e30.4mm\u003c\/td\u003e\n\u003ctd\u003e48x \/ 1.45°\u003c\/td\u003e\n\u003ctd\u003eLow power with a 2\" diagonal\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/explore-scientific-72-ed-30mm-eyepiece\"\u003e30mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e2\"\u003c\/td\u003e\n\u003ctd\u003e25mm\u003c\/td\u003e\n\u003ctd\u003e37.3mm\u003c\/td\u003e\n\u003ctd\u003e40x \/ 1.78°\u003c\/td\u003e\n\u003ctd\u003eUltra-wide views; eyeglass wearers\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/explore-scientific-72-ed-40mm-eyepiece\"\u003e40mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e2\"\u003c\/td\u003e\n\u003ctd\u003e31mm\u003c\/td\u003e\n\u003ctd\u003e48.3mm\u003c\/td\u003e\n\u003ctd\u003e30x \/ 2.31°\u003c\/td\u003e\n\u003ctd\u003eThe widest true field; sweeping the Milky Way\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\u003c\/table\u003e\u003cp\u003eSee all our \u003ca href=\"\/collections\/eyepieces\"\u003eeyepieces\u003c\/a\u003e.\u003c\/p\u003e\n\u003ch2\u003eWhat's in the box\u003c\/h2\u003e\u003cul\u003e\u003cli\u003eExplore Scientific 72° ED 20mm eyepiece with dust caps\u003c\/li\u003e\u003c\/ul\u003e\u003cp\u003eDiagonals, Barlows and filters are sold separately.\u003c\/p\u003e\n\u003ch2\u003eExplore Scientific 72° ED 20mm FAQ\u003c\/h2\u003e\n\u003ch3\u003eWill it fit my telescope?\u003c\/h3\u003e\u003cp\u003eIt has a 1.25\" barrel, which fits nearly every telescope, including those with 2\" focusers when you use the 1.25\" adapter they come with.\u003c\/p\u003e\n\u003ch3\u003eWhat magnification will I get?\u003c\/h3\u003e\u003cp\u003eDivide your telescope's focal length by 20. In an 8\" f\/6 Dobsonian (1200mm) that's 60x; in an 80mm f\/6 refractor (480mm) it's 24x; in a Celestron 8\" SCT (2032mm) it's 102x.\u003c\/p\u003e\n\u003ch3\u003eCan I use it with glasses?\u003c\/h3\u003e\u003cp\u003eIt has 15mm of eye relief, which works without glasses and for many glasses wearers. If you need more, the 15mm and 25mm models have 18mm, and the 30mm and 40mm have 25mm and 31mm.\u003c\/p\u003e\n\u003ch3\u003e20mm, 15mm or 25mm?\u003c\/h3\u003e\u003cp\u003eThe \u003ca href=\"\/products\/explore-scientific-72-ed-15mm-eyepiece\"\u003e15mm\u003c\/a\u003e gives more magnification (80x in an 8\" Dob) for smaller, brighter targets. The \u003ca href=\"\/products\/explore-scientific-72-ed-25mm-eyepiece\"\u003e25mm\u003c\/a\u003e gives a wider, brighter view (48x, 1.45°). The 20mm sits between them at 60x.\u003c\/p\u003e\n\u003ch3\u003eIs it really waterproof?\u003c\/h3\u003e\u003cp\u003eExplore Scientific sells the 72° ED series as waterproof eyepieces, which helps on dewy nights and when cleaning. Dry it before putting the caps back on.\u003c\/p\u003e\n\u003ch2\u003eSpecifications\u003c\/h2\u003e\u003ctable\u003e\u003ctbody\u003e\n\u003ctr\u003e\u003cth colspan=\"2\"\u003eOptics\u003c\/th\u003e\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal length\u003c\/td\u003e\n\u003ctd\u003e20mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApparent field\u003c\/td\u003e\n\u003ctd\u003e72°\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEye relief\u003c\/td\u003e\n\u003ctd\u003e15mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eField stop\u003c\/td\u003e\n\u003ctd\u003e24.8mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eElements\u003c\/td\u003e\n\u003ctd\u003e6 elements in 4 groups\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eED glass\u003c\/td\u003e\n\u003ctd\u003eH-FK61 fluorophosphate crown, Abbe number 81.6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoatings\u003c\/td\u003e\n\u003ctd\u003eMulti-layer\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\u003cth colspan=\"2\"\u003ePhysical\u003c\/th\u003e\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBarrel\u003c\/td\u003e\n\u003ctd\u003e1.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize (L × W)\u003c\/td\u003e\n\u003ctd\u003e79.3mm × 56mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e330g (11.6oz)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWaterproof\u003c\/td\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWarranty\u003c\/td\u003e\n\u003ctd\u003eLimited lifetime (register with Explore Scientific within 60 days)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eManufacturer model\u003c\/td\u003e\n\u003ctd\u003eEPWP7220ED-01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\u003c\/table\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":50206841504003,"sku":"EPWP7220ED-01","price":299.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/IMG_3238.jpg?v=1794254914","url":"https:\/\/milehighastro.com\/products\/explore-scientific-72-ed-20mm-eyepiece","provider":"Mile High Astronomy","version":"1.0","type":"link"}