This Explore Scientific 20mm argon-purged waterproof eyepiece is a fine medium power 1.25" eyepiece whose substantial 68° field of view gives you "big picture" deep space performance with virtually any telescope type.
This new 68° 20mm Explore Scientific is an excellent medium power wide field eyepiece with an unusual benefit. It is O-ring sealed and argon-purged to be 100% waterproof. This prevents internal fogging in the eyepiece; keeps the interior dust-and fungus-free; and makes it easier to clean, as there is no risk of excess cleaning solution getting trapped between the lenses.
Many observers feel that a 68° field eyepiece like this Explore Scientific hits the "sweet spot" between the affordable, but "looking down a tube" view of conventional 45°-50° field eyepieces, and the full-immersion, but very expensive, observing experience of an ultra-wide field 82° or 100° eyepiece.
The 20mm 68° Explore Scientific works with any telescope from a fast focal ratio reflector to a long focal length refractor. It provides a substantial 1.19° field of view (almost two and a half times the diameter of the full Moon) and a bright 3.64mm exit pupil with a 10" f/4.5 Dobsonian at 57x. This gives you about four minutes and forty-five seconds with such a scope to observe an object as it drifts from one side of the eyepiece's flat field to the other. That's plenty of time for multiple observers to look at the object or for you to absorb as much detail as possible before having to reposition your scope.
The eye relief of this six lens/fully multicoated optical system is a respectable 15mm, so observers who must wear eyeglasses when observing will see an almost unvignetted field of view. The eyepiece has a soft fold-down rubber eyecup and comes with dust covers for both ends of the eyepiece.
This individually serial numbered Explore Scientific eyepiece is backed by a limited one year warranty, which will be extended to an Explore Scientific transferable lifetime limited warranty when its warranty card is registered with Explore Scientific within 60 days of purchase. Here's a link to the full details on this unique transferable lifetime warranty.
