{"product_id":"explore-scientific-72-ed-25mm-eyepiece","title":"Explore Scientific 72° ED Series 25mm Waterproof Eyepiece (2\")","description":"\u003ch2\u003eWide, low-power views for a 2-inch focuser\u003c\/h2\u003e\n\u003cp\u003eThe \u003cstrong\u003eExplore Scientific 72° ED Series 25mm Waterproof Eyepiece\u003c\/strong\u003e is a 2-inch low-power eyepiece for expansive views of big clusters and nebulae. It has a 72° apparent field, a 2\" barrel, 18mm of eye relief and a 30.4mm 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 430g (15.2oz).\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eKey specs:\u003c\/strong\u003e 25mm focal length · 72° apparent field · 2\" barrel · 18mm eye relief · 30.4mm field stop · 6 elements in 4 groups · H-FK61 ED glass · waterproof · 430g (15.2oz)\u003c\/p\u003e\n\u003ch2\u003eWhat you'll see\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe Double Cluster\u003c\/strong\u003e in Perseus, both clusters in one view.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM81 and M82\u003c\/strong\u003e together, and the Andromeda Galaxy with M32 and M110.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLarge nebulae:\u003c\/strong\u003e the Veil Nebula and North America Nebula in sections with a UHC or OIII filter.\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 25mm gives 48x and a 1.45° true field. In an 80mm f\/6 refractor (480mm) it gives 19x and a 3.63° 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\u003e18mm eye relief:\u003c\/strong\u003e comfortable for most eyeglass wearers.\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 2\" diagonal or focuser (required):\u003c\/strong\u003e refractors and Schmidt-Cassegrains need a 2\" diagonal such as the \u003ca href=\"\/products\/explore_scientific_2in_diagonal\"\u003eExplore Scientific 2\" Diagonal\u003c\/a\u003e or \u003ca href=\"\/products\/celestron-dielectric-star-diagonal-2-wiith-twist-lock\"\u003eCelestron 2\" Dielectric Star Diagonal\u003c\/a\u003e. Most Dobsonians with a 2\" focuser take it directly.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eA nebula filter:\u003c\/strong\u003e a 2\" UHC or OIII filter threads onto the barrel and makes the Veil and North America Nebulae stand out from suburban skies.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eA Barlow:\u003c\/strong\u003e the \u003ca href=\"\/products\/televue-2x-big-barlow-2\"\u003eTele Vue 2x Big Barlow\u003c\/a\u003e doubles the magnification and turns this eyepiece into an effective 12.5mm.\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-30mm-eyepiece\"\u003e30mm\u003c\/a\u003e and \u003ca href=\"\/products\/explore-scientific-72-ed-20mm-eyepiece\"\u003e20mm\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\u003ca href=\"\/products\/explore-scientific-72-ed-20mm-eyepiece\"\u003e20mm\u003c\/a\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\u003cstrong\u003e25mm\u003c\/strong\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 25mm 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 25mm FAQ\u003c\/h2\u003e\n\u003ch3\u003eWill it fit my telescope?\u003c\/h3\u003e\u003cp\u003eIt has a 2\" barrel, so it needs a 2\" focuser or diagonal. It won't fit a 1.25\"-only focuser.\u003c\/p\u003e\n\u003ch3\u003eWhat magnification will I get?\u003c\/h3\u003e\u003cp\u003eDivide your telescope's focal length by 25. In an 8\" f\/6 Dobsonian (1200mm) that's 48x; in an 80mm f\/6 refractor (480mm) it's 19x; in a Celestron 8\" SCT (2032mm) it's 81x.\u003c\/p\u003e\n\u003ch3\u003eCan I use it with glasses?\u003c\/h3\u003e\u003cp\u003eYes. 18mm of eye relief is enough for most people who observe with glasses.\u003c\/p\u003e\n\u003ch3\u003e25mm, 20mm or 30mm?\u003c\/h3\u003e\u003cp\u003eThe \u003ca href=\"\/products\/explore-scientific-72-ed-20mm-eyepiece\"\u003e20mm\u003c\/a\u003e gives more magnification (60x in an 8\" Dob) for smaller, brighter targets. The \u003ca href=\"\/products\/explore-scientific-72-ed-30mm-eyepiece\"\u003e30mm\u003c\/a\u003e gives a wider, brighter view (40x, 1.78°). The 25mm sits between them at 48x.\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\u003e25mm\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\u003e18mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eField stop\u003c\/td\u003e\n\u003ctd\u003e30.4mm\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\u003e2\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSize (L × W)\u003c\/td\u003e\n\u003ctd\u003e96.4mm × 59.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e430g (15.2oz)\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\u003eEPWP7225ED-01\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\u003c\/table\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":50206850646275,"sku":"EPWP7225ED-01","price":349.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/IMG_3229.jpg?v=1794254954","url":"https:\/\/milehighastro.com\/products\/explore-scientific-72-ed-25mm-eyepiece","provider":"Mile High Astronomy","version":"1.0","type":"link"}