New Explore Scientific Eyepiece
25mm 100 Degree Nitrogen-Purged Waterproof Eyepiece 2"
Manuf. No. Explore Scientific EP10025-01
Free Shipping (within the 48 contiguous US States only)
AVAIL APR 2012

Explore Scientific 25mm 100 Degree field waterproof 2" eyepiece, EP10025-01
The new 25mm Explore Scientific 100 degree field 2" eyepiece is O-ring sealed and argon-purged to be 100% waterproof. To insure a perfect seal, Explore Scientific tests every eyepiece in one meter of water for 30 minutes before shipping.
Internally sealing the eyepiece and purging it with inert, dry argon gas prevents internal fogging in the eyepiece when observing at sub-freezing temperatures. For observers in dusty climates, sealing keeps wind-blown dust and fine particulates from getting into the eyepiece body. For observers in very humid climates, sealing prevents the growth of fungus on the internal lens elements. For all observers, complete sealing maximizes the life of the internal optical coatings and makes the eyepiece easier to clean, as there is no risk of cleaning solution migrating from the top of the lens and seeping around edges to be trapped in between elements.
The 25mm Explore Scientific eyepiece has high contrast, comfortable eye relief, and full field sharpness – with well-controlled astigmatism, field curvature, and lateral color. Its optical system (using lenses of dense crown, light crown, dense flint, and lanthanum rare earth optical glasses) is designed for maximum field/medium power deep space use with telescopes having focal ratios down as low as f/4. It is exceptionally effective on nebulas with fast f/ratio reflectors, such as Dobsonians, as it gives both an immense field and a bright exit pupil (over 5.5mm with the typical f/4.5 Dob). Its very wide field also makes it convenient for moderate power lunar and globular cluster observing with Dobsonians, as you have much longer to observe before the planet drifts out of the field and the scope has to be repositioned than you do with a 60 degree or 70 degree (or even 82 degree) field eyepiece. In addition to Dobs, the new 25mm Explore Scientific Explore Scientific is marvelous for observing open clusters, nebulas, galaxy clusters, and globular clusters with any telescope capable of using a 2" eyepiece.
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Explore Scientific 25mm 100 Degree field waterproof 2" eyepiece, EP10025-01