Explore Scientific 20mm 68 Degree Series Argon-Purged Waterproof Eyepiece EPWP6820-01

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About Explore Scientific 20mm 68 Degree Series

This new 68 degree 20mm Explore Scientific is an excellent medium power wide field eyepiece with an unusual benefit. It is O-ring sealed and nitrogen-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 degree field eyepiece like this Explore Scientific hits the "sweet spot" between the affordable, but "looking down a tube" view of conventional 45 degree field eyepieces, and the full-immersion, but very expensive, observing experience of an ultra-wide field 82 degree or 100 degree eyepiece.The 20mm 68 degree Explore Scientific works with any telescope from a fast focal ratio reflector to a long focal length refractor. It provides a substantial 1.19 degree 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. You can use the calculator below to see just how wide the field will be with your particular 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 product is backed by a limited one year warranty, which will be extended to an Explore Scientific STAR lifetime transferable limited warranty when the product warranty card is registered with Explore Scientific within