{"title":"Explore Scientific 72° ED Series","description":"\u003cp\u003eEvery Explore Scientific 72° ED Series eyepiece we stock, listed by focal length.\u003c\/p\u003e","products":[{"product_id":"72-ed-series-6-5mm-waterproof-eyepiece","title":"Explore Scientific 72° ED Series 6.5mm Waterproof Eyepiece","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific 72° ED Series 6.5mm is a short focal length waterproof eyepiece with a 1.25-inch barrel, built around extra-low-dispersion glass. At 6.5mm it is a high-magnification eyepiece: in a 988mm refractor it gives 152x, in a 1500mm Maksutov 231x.\u003c\/p\u003e\n\u003cp\u003eThe 72° apparent field sits between the 68° Series and the 82° Series — wide enough that an object at high power stays in view noticeably longer than it would in a 52° eyepiece, without the outer-field demands of a 100° design.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eLunar and planetary observers:\u003c\/strong\u003e 6.5mm is a working high-power focal length in most apertures, and ED glass is aimed squarely at the colour and contrast that planetary detail depends on.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDouble-star observers\u003c\/strong\u003e needing magnification without a field so narrow that the pair drifts out between looks.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUndriven and Dobsonian users:\u003c\/strong\u003e the wider apparent field buys drift time at high power on an unguided mount.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyeglass wearers:\u003c\/strong\u003e Explore Scientific specifies generous eye relief for the series, which is the usual constraint at this focal length.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eExtra-low-dispersion (ED) glass:\u003c\/strong\u003e reduces chromatic aberration within the eyepiece itself, which shows as cleaner colour separation and higher contrast on planetary detail.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e72° apparent field of view:\u003c\/strong\u003e more immersive than the 52° and 62° Series, and easier on the outer field than the 82° and 100° designs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.25″ barrel:\u003c\/strong\u003e fits any standard 1.25-inch focuser or diagonal directly.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWaterproof construction,\u003c\/strong\u003e consistent with the sealed housings used across the Explore Scientific waterproof eyepiece range.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGenerous eye relief\u003c\/strong\u003e for the focal length, which keeps extended sessions comfortable and makes observing with glasses on practical.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eHigh-power lunar and planetary observing.\u003c\/li\u003e\n\u003cli\u003eSplitting double stars.\u003c\/li\u003e\n\u003cli\u003eCompact deep-sky targets — planetary nebulae and globular cluster cores.\u003c\/li\u003e\n\u003cli\u003eHigh-power observing on an undriven mount, where apparent field translates directly into time on target.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits any 1.25-inch focuser or diagonal.\u003c\/strong\u003e In a 2-inch focuser it needs a 2-inch to 1.25-inch adapter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMagnification:\u003c\/strong\u003e telescope focal length ÷ 6.5. A 1200mm SCT gives 185x; a 750mm Newtonian gives 115x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFilters:\u003c\/strong\u003e takes standard 1.25-inch threaded filters.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWithin the series:\u003c\/strong\u003e the 72° ED Series runs 6.5mm, 8.5mm, 11.5mm, 15mm, 20mm, 25mm, 30mm and 40mm, so a matched set holds the same apparent field and eye position across focal lengths.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e6.5mm is a high-power eyepiece, and seeing governs it.\u003c\/strong\u003e On a steady night in a 6-inch or larger telescope it will show what the aperture can do; on a turbulent night a longer focal length will show more. That is atmosphere, not optics.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExplore Scientific does not currently publish a full specification table for this series.\u003c\/strong\u003e Eye relief, field stop diameter, element count and weight are not given on their product page, so those rows are absent below rather than estimated. If you need a specific figure before ordering, ask us and we will put the question to our Explore Scientific rep.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is a visual eyepiece.\u003c\/strong\u003e Eyepiece-projection imaging is possible with an adapter, but the design target is the eye.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo — it drops into any 1.25-inch focuser or diagonal and is ready immediately. Nothing to assemble or adjust.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat magnification will I get?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eDivide your telescope's focal length in millimetres by 6.5. A 1000mm telescope gives 154x.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat does the ED glass actually change?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eExtra-low-dispersion glass brings wavelengths closer to a common focus inside the eyepiece, so colour edges on bright targets are cleaner and fine planetary contrast holds up better than in a standard-glass design of the same field.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does it compare to the 82° Series at the same focal length?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe 82° gives a wider, more immersive field; the 72° ED is built around glass type and eye relief instead. Which one suits you depends on whether you value field width or comfort and colour correction more — tell us what you observe and we will give you a straight answer.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use it with glasses on?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eExplore Scientific specifies generous eye relief for this series, which is what makes that practical. They do not publish the figure in millimetres, so we are not going to quote one — if it is the deciding factor for you, ask and we will confirm it with our rep first.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: a 6.5mm ED-glass eyepiece with a 72° field and a 1.25-inch barrel — high magnification with more field and more eye relief than a short-focal-length eyepiece usually offers. If you are filling out a focal-length set for a particular telescope, send us its aperture and focal length and we will map out which of the series make sense.\u003c\/p\u003e\n","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":52950319431791,"sku":"EPWP7265ED-01","price":415.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/EPWP7265ED-01.webp?v=1776180613"},{"product_id":"72-ed-series-8-5mm-waterproof-eyepiece","title":"Explore Scientific 72° ED Series 8.5mm Waterproof Eyepiece","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific 72° ED Series 8.5mm is a waterproof eyepiece with a 1.25-inch barrel, built around extra-low-dispersion glass and a 72-degree apparent field. Explore Scientific positions the series for planetary work and deep-sky objects alike, and specifies long eye relief as one of its design priorities.\u003c\/p\u003e\n\u003cp\u003e8.5mm is a high-power focal length in nearly any telescope. In a 714mm refractor it works at 84x, in a 1000mm instrument 118x, in a 1500mm Maksutov 176x. That range covers the magnifications where lunar and planetary detail lives without pushing straight into the territory that only exceptional seeing supports.\u003c\/p\u003e\n\u003cp\u003eThe 72° field sits between the 68° and 82° Series. It is wide enough that an object at high power stays in a hand-guided field noticeably longer, while keeping the eye position and outer-field correction less demanding than a 100° design.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlanetary observers:\u003c\/strong\u003e ED glass targets exactly the colour error and contrast loss that fine planetary detail depends on, and 8.5mm reaches the magnification range where that detail appears.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyeglass wearers:\u003c\/strong\u003e Explore Scientific specifies long eye relief for the series, and eye relief is normally the first casualty at short focal lengths.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDobsonian and undriven-mount users:\u003c\/strong\u003e a 72° apparent field converts directly into drift time, which is the practical currency of high-power observing without tracking.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDouble-star observers\u003c\/strong\u003e who want magnification without a field so tight that the pair leaves view between looks.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eObservers filling a gap:\u003c\/strong\u003e 8.5mm falls between the more common 9mm and 8mm steps, which makes it useful for splitting the difference in an existing set.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eExtra-low-dispersion (ED) glass:\u003c\/strong\u003e reduces chromatic aberration generated inside the eyepiece itself, which shows as cleaner colour edges on bright targets and better-held contrast on subtle planetary shading.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e72° apparent field of view:\u003c\/strong\u003e more field than the 52° and 62° Series, less demanding at the edge than the 82° and 100° designs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLong eye relief\u003c\/strong\u003e specified for the series, which is what makes extended sessions and observing with glasses on practical at a short focal length.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWaterproof construction,\u003c\/strong\u003e consistent with the sealed housings Explore Scientific uses across its waterproof eyepiece range.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.25-inch barrel\u003c\/strong\u003e fitting any standard focuser or diagonal.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e8.5mm focal length,\u003c\/strong\u003e a step that sits between the usual 8mm and 9mm offerings.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eHigh-power lunar observing, where ED glass keeps the limb clean.\u003c\/li\u003e\n\u003cli\u003ePlanetary detail on Jupiter, Saturn and Mars at magnifications the aperture supports.\u003c\/li\u003e\n\u003cli\u003eSplitting close double stars.\u003c\/li\u003e\n\u003cli\u003eCompact deep-sky targets — planetary nebulae, small galaxies and globular cluster cores.\u003c\/li\u003e\n\u003cli\u003eHigh-power observing on a hand-guided mount, where apparent field is what buys time on target.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits any 1.25-inch focuser or diagonal.\u003c\/strong\u003e In a 2-inch focuser it seats with a 2-inch to 1.25-inch adapter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMagnification:\u003c\/strong\u003e telescope focal length ÷ 8.5. A 750mm Newtonian gives 88x, a 1200mm SCT gives 141x, a 2000mm SCT gives 235x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFilters:\u003c\/strong\u003e takes standard 1.25-inch threaded filters, including lunar, colour and narrowband types.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFocal extenders:\u003c\/strong\u003e a 2x extender makes this an effective 4.25mm, which reaches magnifications that only steady nights and larger apertures support.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWithin the series:\u003c\/strong\u003e the 72° ED Series spans several focal lengths, so a matched set holds the same apparent field and a consistent eye position from low power to high.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eExplore Scientific does not publish a specification table for this eyepiece.\u003c\/strong\u003e Eye relief in millimetres, field stop diameter, element count, body dimensions and weight are all absent from their product page, so those rows read as not published below rather than carrying an estimate. If a specific figure decides the purchase for you, ask and we will put the question to our Explore Scientific rep.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e8.5mm is governed by the atmosphere as much as by the optics.\u003c\/strong\u003e On a steady night in a 6-inch or larger telescope it will show what the aperture can do; on a turbulent night a longer focal length shows more. That is seeing rather than glass.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTrue field cannot be calculated precisely without a field stop figure.\u003c\/strong\u003e The 72° apparent field divided by the working magnification gives a close approximation — roughly 0.6° at 118x — and that is the honest way to estimate it here.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is a visual eyepiece.\u003c\/strong\u003e Eyepiece-projection imaging is possible with the right adapter, though the design target is the eye rather than a sensor.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo — it slides into any 1.25-inch focuser or diagonal and is ready to observe with straight away. Nothing to assemble, align or adjust.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat magnification will I get?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eDivide your telescope's focal length in millimetres by 8.5. A 1000mm telescope gives 118x; a 1500mm gives 176x.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat does ED glass do in an eyepiece?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eExtra-low-dispersion glass spreads wavelengths less than standard optical glass, so the eyepiece brings colours closer to a common focus. In practice that means cleaner edges on bright objects and fine planetary contrast that holds up better than in a conventional-glass design of the same field.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I observe with glasses on?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eExplore Scientific specifies long eye relief for this series, which is what makes that practical. They do not publish the figure in millimetres, so no number is quoted here — if it is the deciding factor, ask and we will get it confirmed first.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does it compare to the 82° Series at a similar focal length?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe 82° gives a wider, more immersive field; the 72° ED is built around glass type and eye comfort instead. Which one suits you comes down to whether field width or colour correction and eye relief matters more for what you observe — tell us and we will give you a straight comparison.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhy 8.5mm rather than 8 or 9?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eIt is a deliberate half-step. In a set that already has a 6mm and an 11mm, 8.5mm lands neatly in between rather than duplicating a power you already own.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: an 8.5mm ED-glass eyepiece with a 72° apparent field, long eye relief and a 1.25-inch waterproof barrel — high magnification with more field and more eye comfort than short focal lengths usually allow. If you are working out how it fits alongside eyepieces you already own, send us the list and your telescope's focal length and we will show you where the gaps are.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":52950319464559,"sku":"EPWP7285ED-01","price":415.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/EPWP7285ED-01.webp?v=1776180692"},{"product_id":"72-ed-series-11-5mm-waterproof-eyepiece","title":"Explore Scientific 72° ED Series 11.5mm Waterproof Eyepiece","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific 72° ED Series 11.5mm is a waterproof eyepiece with a 1.25-inch barrel, built around extra-low-dispersion glass and a 72-degree apparent field. It carries item number EPWP72115ED-01.\u003c\/p\u003e\n\u003cp\u003eEleven and a half millimetres lands in an interesting place. It is not the shortest focal length in a set and not a general-purpose medium, but the step where a telescope starts working near its resolution limit while the exit pupil is still large enough to be forgiving. In a 1200mm Schmidt-Cassegrain it gives 104x; in a 1900mm Maksutov, 165x; in a 750mm Newtonian, 65x; in a 1000mm refractor, 87x. On most instruments that is the magnification you settle at once the target is found and the seeing has been assessed — high enough for planetary detail and globular cluster resolution, low enough that a moment of poor seeing does not end the view.\u003c\/p\u003e\n\u003cp\u003eThe exit pupil follows from the telescope's focal ratio: 11.5 divided by f\/6 gives 1.9mm, divided by f\/10 gives 1.15mm. Both are in the range where the eye's own aberrations stay out of the way and a faint galaxy still has enough surface brightness to register.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlanetary observers:\u003c\/strong\u003e ED glass inside the eyepiece is aimed at exactly the colour errors that blur fine low-contrast detail on Jupiter and Mars.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDouble-star observers:\u003c\/strong\u003e 11.5mm produces working high power in most apertures while leaving enough field that a pair does not vanish between glances.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGlobular cluster observers:\u003c\/strong\u003e this is roughly where a cluster stops being a fuzzy ball and starts resolving into individual stars in a mid-aperture telescope.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyeglass wearers:\u003c\/strong\u003e Explore Scientific specify eye relief for this series as comfortable enough to observe with glasses on, which is unusual at a focal length this short.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDobsonian and undriven-mount users:\u003c\/strong\u003e 72 degrees of apparent field translates directly into more seconds on target between nudges at high magnification.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e11.5mm focal length:\u003c\/strong\u003e the high-power working step — 87x in a 1000mm telescope, 165x in a 1900mm one.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExtra-low-dispersion glass:\u003c\/strong\u003e ED elements inside the eyepiece reduce the eyepiece's own contribution to chromatic aberration, which shows up as cleaner edges on bright targets and better fine contrast.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e72° apparent field of view:\u003c\/strong\u003e substantially wider than a 52° or 62° design, and less demanding on eye placement than the 82° and 100° Series.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.25-inch barrel:\u003c\/strong\u003e fits any standard 1.25-inch focuser or star diagonal directly, and a 2-inch focuser with an adapter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eComfortable eye relief for the focal length:\u003c\/strong\u003e the property that usually gets sacrificed first as eyepiece focal length drops, and the one Explore Scientific calls out for this series.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWaterproof construction:\u003c\/strong\u003e a sealed housing, consistent with the waterproof eyepiece range Explore Scientific builds.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eLunar detail along the terminator at working high power.\u003c\/li\u003e\n\u003cli\u003ePlanetary observing — belt structure on Jupiter, the Cassini division, Martian surface markings during a favourable opposition.\u003c\/li\u003e\n\u003cli\u003eSplitting double stars at magnifications where the pair is well separated but still bright.\u003c\/li\u003e\n\u003cli\u003eResolving globular clusters and picking out the central stars of planetary nebulae.\u003c\/li\u003e\n\u003cli\u003eHigh-power observing on an undriven mount, where apparent field is what buys observing time.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits any 1.25-inch focuser or diagonal.\u003c\/strong\u003e In a 2-inch focuser it needs a 2-inch to 1.25-inch adapter, which we stock.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMagnification:\u003c\/strong\u003e telescope focal length divided by 11.5. A 650mm refractor gives 57x, a 1500mm Maksutov gives 130x, a 2000mm SCT gives 174x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFilters:\u003c\/strong\u003e the 1.25-inch barrel takes standard 1.25-inch threaded filters — neutral density and variable polarisers for the Moon, colour filters for planetary contrast, narrowband for nebulae.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFocal extenders:\u003c\/strong\u003e a 2x extender in front of this eyepiece produces an effective 5.75mm, which is past the useful magnification of smaller apertures. On a large instrument on a steady night it has its place; on most nights the eyepiece on its own is doing the right thing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGlasses:\u003c\/strong\u003e the series is specified for comfortable eye relief, and a fold-down eyecup is what lets a spectacle lens sit close enough to take in the whole field. Explore Scientific does not publish the eye relief in millimetres for this model, so we are not going to quote a figure — if it is your deciding factor, we will confirm it with our rep first.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSeeing governs an 11.5mm eyepiece more than the optics do.\u003c\/strong\u003e On a steady night in a mid-aperture telescope it will show what the aperture is capable of; on a turbulent night a longer focal length shows more. That is the atmosphere, not the eyepiece, and it is the reason most observers own several focal lengths.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExplore Scientific does not publish a full specification table for this model.\u003c\/strong\u003e Eye relief in millimetres, field stop diameter, element count, coating specification and weight are absent from their page, so those rows are blank below rather than estimated. We are happy to put any of them to our Explore Scientific rep if you need the number before ordering.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e72 degrees is wide, and wide eyepieces reward good eye placement.\u003c\/strong\u003e Taking a moment to settle the eye at the right distance is what brings the field edge into view, and the fold-down eyecup is there to make that position repeatable.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is a visual eyepiece.\u003c\/strong\u003e Eyepiece projection onto a camera is possible with an adapter, though the design intent is the observer's eye.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo. It drops into any 1.25-inch focuser or diagonal and is ready to use immediately — nothing to assemble, nothing to adjust.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat magnification will I get?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eDivide your telescope's focal length in millimetres by 11.5. A 1000mm telescope gives 87x, a 1200mm gives 104x.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat difference does the ED glass make?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eExtra-low-dispersion glass bends the different wavelengths by more similar amounts than ordinary optical glass, so the eyepiece adds less colour error of its own on top of whatever the telescope delivers. In practice that reads as cleaner edges on the lunar limb and bright planets, and a little more of the fine contrast that planetary detail depends on.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use it with a 2-inch focuser?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes, with a 2-inch to 1.25-inch adapter. Most 2-inch star diagonals include one.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does it compare with the 82° Series at a similar focal length?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe 82° Series gives a wider and more immersive field; the 72° ED Series is built around glass type and eye comfort instead. Which suits you depends on whether field width or colour correction and eye relief matters more for the observing you do — tell us what you look at most and we will give you an honest steer.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill it work on a Dobsonian?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes, and the 72-degree field is one of the reasons to choose it for one. At 11.5mm in a typical Dobsonian focal length the magnification is high, and the wider apparent field is what keeps the object in view longer between nudges.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: an 11.5mm ED-glass eyepiece with a 72-degree field and a 1.25-inch barrel, sealed against weather and specified with enough eye relief to work with glasses on — the high-power step that still leaves room to breathe. If you are filling out a focal-length set for a particular telescope, send us its aperture and focal length and we will map out which focal lengths would actually add something.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":52950319595631,"sku":"EPWP72115ED-01","price":415.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/EPWP72115ED-01.webp?v=1776180786"},{"product_id":"72-ed-series-15mm-waterproof-eyepiece","title":"Explore Scientific 72° ED Series 15mm Waterproof Eyepiece","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific 72° ED Series 15mm is a medium-focal-length waterproof eyepiece on a 1.25-inch barrel, built around extra-low-dispersion glass. It presents a 72° apparent field, and Explore Scientific specifies generous eye relief for the series as a design goal rather than an afterthought.\u003c\/p\u003e\n\u003cp\u003eAt 15mm it lands in the most-used part of a focal-length set. In a 952mm refractor it gives 63x; in a 1200mm Schmidt-Cassegrain, 80x; in a 1500mm Maksutov, 100x; in a 480mm short refractor, 32x. That is the range where most deep-sky observing happens — high enough to darken the background sky and pull out structure, low enough that the exit pupil stays comfortable and the object still has room to breathe.\u003c\/p\u003e\n\u003cp\u003eThe 72° field sits between the 68° Series and the 82° Series. It is wide enough that an object at medium power drifts across the field slowly on an undriven mount, without asking the outer field to perform the way a 100° design does.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDeep-sky observers\u003c\/strong\u003e working clusters and nebulae, where 15mm is often the single most productive focal length in the case.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDobsonian and undriven-mount users:\u003c\/strong\u003e a wider apparent field converts directly into more seconds on target between nudges.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyeglass wearers:\u003c\/strong\u003e Explore Scientific builds generous eye relief into this series, which is the usual sticking point once focal lengths drop below 20mm.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eObservers who want colour fidelity:\u003c\/strong\u003e the ED glass is there to keep colour edges clean on bright stars and to hold contrast on planetary detail.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAnyone observing in dew or damp air:\u003c\/strong\u003e the waterproof housing is consistent with the sealed construction used across the Explore Scientific waterproof eyepiece range.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eExtra-low-dispersion (ED) glass:\u003c\/strong\u003e reduces chromatic aberration generated inside the eyepiece itself, which shows up as cleaner colour separation on bright stars and better-held contrast on fine detail.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e72° apparent field of view:\u003c\/strong\u003e a genuinely wide field that still keeps the outer zone well behaved, and one that suits both framing large objects and holding smaller ones in view.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e15mm focal length:\u003c\/strong\u003e the workhorse power in most telescopes, and the one most observers reach for first on a deep-sky target.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.25″ barrel:\u003c\/strong\u003e fits any standard 1.25-inch focuser or diagonal directly, with no adapter needed.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWaterproof construction,\u003c\/strong\u003e in line with the sealed housings Explore Scientific uses across its waterproof eyepiece lines.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGenerous eye relief for the focal length,\u003c\/strong\u003e which keeps long sessions comfortable and makes observing with glasses on practical.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eMedium-power deep-sky observing — open clusters, globular clusters, emission and reflection nebulae, and the brighter galaxies.\u003c\/li\u003e\n\u003cli\u003eLunar observing at moderate magnification, where the whole disc or a large region frames well.\u003c\/li\u003e\n\u003cli\u003eObserving on an undriven Dobsonian, where 72° of apparent field buys drift time.\u003c\/li\u003e\n\u003cli\u003eObserving with eyeglasses on, where the series' eye relief is the enabling factor.\u003c\/li\u003e\n\u003cli\u003eFilling the mid-power slot in a matched 72° ED set so the apparent field and eye position stay consistent as you change magnification.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits any 1.25-inch focuser or diagonal.\u003c\/strong\u003e In a 2-inch focuser it seats in a 2-inch to 1.25-inch adapter, which we stock.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMagnification:\u003c\/strong\u003e telescope focal length ÷ 15. A 750mm Newtonian gives 50x; a 1000mm telescope 67x; a 2000mm SCT 133x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExit pupil:\u003c\/strong\u003e 15mm divided by your telescope's focal ratio. That is 2.5mm at f\/6 and 1.5mm at f\/10 — comfortable figures for extended deep-sky viewing.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFilters:\u003c\/strong\u003e takes standard 1.25-inch threaded filters. At 15mm a UHC or O-III filter is the classic pairing for emission nebulae, and a broadband filter helps from a light-polluted site.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFocal extenders:\u003c\/strong\u003e a 2x extender gives the magnification of a 7.5mm eyepiece while retaining the eye position and field character of the 15mm, which is a useful route to high power for eyeglass wearers.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWithin the series:\u003c\/strong\u003e the 72° ED Series spans several focal lengths, so a matched set holds the same apparent field and a similar eye position as you move through magnifications.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eExplore Scientific does not currently publish a specification table for this eyepiece.\u003c\/strong\u003e Eye relief in millimetres, field stop diameter, element count, physical dimensions and weight are not given on their product page, so those rows appear below as unpublished rather than estimated. If you need a specific figure before ordering, ask us and we will put the question to our Explore Scientific rep.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWithout a published field stop, we cannot calculate your true field precisely.\u003c\/strong\u003e A reasonable working estimate comes from apparent field divided by magnification, but that is an approximation rather than a specification, so we leave the row blank rather than fill it.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is a visual eyepiece.\u003c\/strong\u003e Eyepiece-projection imaging is possible with the right adapter, but the design target here is the eye.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e72° is wide, and wide fields ask for good eye placement.\u003c\/strong\u003e Taking in the whole field means holding your eye in the right position rather than pressing it to the lens — a habit that comes quickly and pays off across every wide-field eyepiece you own.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eED glass addresses colour generated inside the eyepiece,\u003c\/strong\u003e not colour produced by your telescope's objective. In a fast achromatic refractor, the objective remains the dominant source of any fringing you see, and a minus-violet filter is the tool for that end of the problem.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo — it drops into any 1.25-inch focuser or diagonal and is ready immediately. Nothing to assemble, collimate or adjust.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat magnification will I get?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eDivide your telescope's focal length in millimetres by 15. A 1200mm telescope gives 80x.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat does the ED glass actually change?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eExtra-low-dispersion glass brings different wavelengths closer to a common focus inside the eyepiece, so colour edges around bright stars are cleaner and fine low-contrast detail holds up better than it does in a standard-glass design of the same field width.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use it with glasses on?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eExplore Scientific specifies generous eye relief for this series, which is what makes that practical. They do not publish the figure in millimetres, so we would rather not quote one — if it is the deciding factor, ask and we will confirm it with our rep first.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow wide a true field does it give?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThat depends on the field stop diameter, which Explore Scientific does not publish for this eyepiece. Dividing the 72° apparent field by your magnification gives a close working figure, and we can get the exact number from our rep if you need it.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does it compare with the 82° Series at the same focal length?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe 82° gives a wider, more immersive field; the 72° ED is built around glass type and eye relief instead, in a lighter and more compact body. Which suits you depends on whether field width or comfort and colour correction matters more in your observing — tell us how you observe and we will give you an honest answer.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs it suitable for a Dobsonian?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eVery much so. The wider apparent field is exactly what an undriven mount benefits from, since an object at 72° takes noticeably longer to cross the field than it would in a narrow-field eyepiece at the same magnification.\u003c\/p\u003e\n\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: a 15mm ED-glass eyepiece with a 72° field, a 1.25-inch barrel and waterproof construction — the most-used magnification in most telescopes, with more field and more eye relief than the focal length usually brings. If you are building out a focal-length set for a particular telescope, send us its aperture and focal length and we will work out which of the series make sense together.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":52950319825007,"sku":"EPWP7215ED-01","price":415.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/EPWP7215ED-01.webp?v=1776180866"},{"product_id":"72-ed-series-20mm-waterproof-eyepiece","title":"Explore Scientific 72° ED Series 20mm Waterproof Eyepiece","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Explore Scientific 72° ED Series 20mm is a low-to-mid power waterproof eyepiece with a 1.25-inch barrel, built around extra-low-dispersion glass. Explore Scientific specifies a 72° apparent field of view and describes the optical design as using ED glass to reduce chromatic aberration, raise contrast and sharpen both planetary and deep-sky views, with comfortable eye relief for long sessions.\u003c\/p\u003e\n\u003cp\u003eAt 20mm this is the focal length most observers reach for as a working general-purpose eyepiece: in a 714mm refractor it gives 36x, in a 1200mm SCT 60x, in a 1500mm Dobsonian 75x. It is low enough to frame a cluster, high enough to start pulling structure out of a nebula, and it sits comfortably between a finder-like sweeping eyepiece and the high-power end of a set.\u003c\/p\u003e\n\u003cp\u003eThe 72° apparent field sits between the 68° Series and the 82° Series. It is wide enough that the field edge stops feeling like a tunnel, without the demands a 100° design places on the outer field or on the size and weight of the housing.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDeep-sky observers\u003c\/strong\u003e who want a wide, contrasty mid-power view for open clusters, brighter galaxies and the large nebulae.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDobsonian and undriven mount users:\u003c\/strong\u003e a 72° field at 20mm gives real drift time before an object needs nudging back to centre.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eObservers who prefer a single go-to focal length\u003c\/strong\u003e that covers most of a night's targets without constant eyepiece changes.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEyeglass wearers:\u003c\/strong\u003e Explore Scientific specifies comfortable eye relief for the series, which is what makes observing with spectacles practical.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eObservers building a matched 72° ED set\u003c\/strong\u003e so apparent field and eye position stay consistent from one focal length to the next.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAnyone who observes in dew or damp air:\u003c\/strong\u003e the waterproof housing is built for it.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eExtra-low-dispersion (ED) glass:\u003c\/strong\u003e reduces chromatic aberration generated inside the eyepiece itself, which shows up as cleaner colour edges on bright stars and better contrast on subtle detail.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e72° apparent field of view:\u003c\/strong\u003e more open than the 52° and 62° Series, and less demanding on the outer field than the 82° and 100° designs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e20mm focal length:\u003c\/strong\u003e the mid-range workhorse position in most eyepiece sets.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.25″ barrel:\u003c\/strong\u003e fits any standard 1.25-inch focuser or diagonal directly.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWaterproof construction,\u003c\/strong\u003e consistent with the sealed housings used across the Explore Scientific waterproof eyepiece range.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eComfortable eye relief\u003c\/strong\u003e specified for the series, which is what keeps a long session from becoming a squint.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eGeneral deep-sky observing — open clusters, brighter galaxies, large nebulae.\u003c\/li\u003e\n\u003cli\u003eFraming and locating targets before switching to a shorter focal length.\u003c\/li\u003e\n\u003cli\u003eWide low-power lunar views showing the whole disc with room around it.\u003c\/li\u003e\n\u003cli\u003eObserving on an undriven mount, where apparent field translates directly into time on target.\u003c\/li\u003e\n\u003cli\u003eOutreach and shared sessions, where a wide field makes it easier for a newcomer at the eyepiece to see what they are meant to be looking at.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits any 1.25-inch focuser or diagonal.\u003c\/strong\u003e In a 2-inch focuser it takes a 2-inch to 1.25-inch adapter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMagnification:\u003c\/strong\u003e telescope focal length ÷ 20. A 952mm refractor gives 48x; a 1900mm Maksutov gives 95x; a 750mm Newtonian gives 38x.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExit pupil:\u003c\/strong\u003e 20mm ÷ the telescope's focal ratio — 4mm at f\/5, 2mm at f\/10. A 4mm exit pupil is a comfortable dark-site figure.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFocal extenders:\u003c\/strong\u003e a 20mm eyepiece behind a 2x extender behaves like a 10mm while keeping the eye relief of the longer eyepiece, which is a useful trick for spectacle wearers.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWithin the series:\u003c\/strong\u003e the 72° ED Series covers a range of focal lengths, so a matched set holds the same apparent field and eye position throughout.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFilters:\u003c\/strong\u003e Explore Scientific does not publish the filter thread specification for this model, so we are not quoting one. If you intend to run a UHC or O-III filter, ask and we will confirm the thread with our rep first.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eExplore Scientific has not published a full specification table for this eyepiece.\u003c\/strong\u003e Eye relief in millimetres, field stop diameter, element count, coatings, physical dimensions and weight are all absent from their product page, so those rows read \"Not published by vendor\" below rather than carrying an estimate. If you need a specific figure before ordering, ask us and we will put the question to our Explore Scientific rep.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWithout a published field stop diameter, true field cannot be calculated exactly.\u003c\/strong\u003e The 72° apparent field divided by the magnification gives a close approximation, and that is the honest way to work it out until the figure is published.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThis is a recently listed product.\u003c\/strong\u003e Explore Scientific has not yet published a barcode or shipping weight for it, which is normal for a new addition to a series and tends to fill in over time.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is a visual eyepiece.\u003c\/strong\u003e Eyepiece-projection imaging is possible with an adapter, but the design target is the eye.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIn a fast telescope, a 20mm eyepiece produces a large exit pupil.\u003c\/strong\u003e At f\/4 that is 5mm, which suits a dark site and shows sky glow under city lights. A narrowband filter or a shorter focal length is the usual remedy, and we stock both.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo — it drops into any 1.25-inch focuser or diagonal and is ready immediately. There is nothing to assemble or adjust.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat magnification will I get?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eDivide your telescope's focal length in millimetres by 20. A 1000mm telescope gives 50x.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat does the ED glass change?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eExtra-low-dispersion glass brings the different wavelengths closer to a common focus inside the eyepiece, so colour edges on bright stars are cleaner and fine contrast holds up better than a standard-glass design of the same field would manage.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does it compare to the 82° Series at a similar focal length?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe 82° gives a wider, more immersive field; the 72° ED is built around glass type and eye relief instead. Which suits you depends on whether field width or comfort and colour correction matters more — tell us what you observe and we will give you a straight answer.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow much eye relief does it have?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eExplore Scientific describes it as comfortable for extended observing but does not publish the figure in millimetres, so we are not going to quote one. If it is the deciding factor, ask and we will confirm it with our rep first.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs it a good match for a Dobsonian?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes. At 20mm with a 72° field it gives a wide, easy view on an undriven mount, and objects take noticeably longer to drift out than they would in a narrower eyepiece.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use it with a focal extender?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes — a 2x extender turns it into the equivalent of a 10mm while preserving the longer eyepiece's eye relief, which many observers prefer to a native 10mm.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: a 20mm ED-glass eyepiece with a 72° apparent field in a waterproof 1.25-inch barrel — the mid-range focal length most nights get built around, with a wider field and better colour correction than a standard-glass design of the same size. If you are filling out a set for a particular telescope, send us its aperture and focal length and we will map out which focal lengths make sense alongside it.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":52950321266799,"sku":"EPWP7220ED-01","price":415.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/EPWP7220ED-01.webp?v=1776181164"},{"product_id":"72-ed-series-25mm-waterproof-eyepiece","title":"72° ED Series 25mm Waterproof Eyepiece","description":"\u003cp\u003eThe Explore Scientific 72 degree ED 25mm eyepiece with a 2 inch barrel is designed for expansive, low power viewing that reveals the broader structure of the night sky. It is ideal for observing large deep sky objects and sweeping rich star fields. The wider 2 inch format allows for a larger field stop, enhancing the 72 degree apparent field of view and creating a more immersive experience. This makes it easier to frame large objects and enjoy them in full context.\u003c\/p\u003e\n\u003cp\u003eExtra low dispersion glass ensures that image quality remains sharp and well corrected across the field. Color fringing is minimized, and contrast is enhanced, resulting in a cleaner and more natural view. The generous eye relief allows for comfortable viewing, even during extended sessions.\u003c\/p\u003e\n\u003cp\u003eThis eyepiece is a strong choice for those who want to maximize field of view and brightness while maintaining excellent image quality.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":52950321496175,"sku":"EPWP7225ED-01","price":484.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/EPWP7225ED-01.webp?v=1776181258"},{"product_id":"72-ed-series-30mm-waterproof-eyepiece","title":"72° ED Series 30mm Waterproof Eyepiece","description":"\u003cp\u003eThe Explore Scientific 72 degree ED 30mm eyepiece with a 2 inch barrel is built for ultra wide, low magnification viewing that allows you to fully immerse yourself in the night sky. It is particularly well suited for observing large nebulae, open clusters, and sweeping star fields. The 2 inch barrel design enhances the field of view, allowing for a broader and more expansive perspective. Combined with the 72 degree apparent field of view, this creates a truly immersive viewing experience.\u003c\/p\u003e\n\u003cp\u003eThe extra low dispersion glass maintains image quality across the field by reducing chromatic aberration and improving contrast. This ensures that even at lower magnifications, the view remains sharp and well defined. The eyepiece is designed for comfort, with long eye relief that supports extended observation.\u003c\/p\u003e\n\u003cp\u003eThis focal length is ideal for those who want to explore the sky at a wider scale and appreciate the full structure of large celestial objects.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":52950323396719,"sku":"EPWP7230ED-01","price":553.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/EPWP7230ED-01.webp?v=1776181299"},{"product_id":"72-ed-series-40mm-waterproof-eyepiece","title":"72° ED Series 40mm Waterproof Eyepiece","description":"\u003cp\u003ethe series, making it ideal for sweeping the night sky and observing the largest celestial objects. With its 2 inch barrel and expansive 72 degree apparent field of view, this eyepiece provides a truly immersive perspective. It allows you to take in entire star fields and large deep sky objects in a single view.\u003c\/p\u003e\n\u003cp\u003eThe extra low dispersion glass ensures that image quality remains sharp and well corrected, with reduced color fringing and improved contrast. This results in a clean and natural viewing experience even at very low magnification. The comfortable eye relief supports long, relaxed observing sessions.\u003c\/p\u003e\n\u003cp\u003eThis eyepiece is the ultimate wide field option for those who want to experience the full scale of the night sky.\u003c\/p\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":52950333227119,"sku":"EPWP7240ED-01","price":623.95,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/EPWP7240ED-01.webp?v=1776181411"}],"url":"https:\/\/ontariotelescope.com\/collections\/explore-scientific-72-degree.oembed","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}