This 2” 18mm Explore Scientific is an exceptional medium focal length eyepiece with a wide, wide 82° field. It makes observing feel like you’re floating above the Earth, taking a space walk, rather than looking through a telescope eyepiece, particularly with short focal length scopes such as fast focal ratio apo refractors or Dobsonian reflectors.
In addition to its wide field, the 18mm Explore Scientific has an extra benefit for you. 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.
The latest computer design programs have been used to optimize its performance. Its six element/four group design uses low dispersion and high refractive index lenses and full multicoatings for high contrast, high resolution, and flat field images across its very wide 82° field of view. The lens edges have been blackened to improve contrast.
A 10" f/4.5 Dobsonian reflector will have a full 1.29° field at 63.5x with this eyepiece, able to encompass all of the Pleiades in one field. Even an 8” f/10 catadioptric will have a field almost one and a half lunar diameters across, able to encompass the full Moon with room to spare, the Orion Nebula, and many globular clusters, as well. You can use the calculator in the "formula" tab above to see just how wide the field will be with your particular telescope.
At 13mm, the eye relief will somewhat vignette the field of view for eyeglass wearers. This isn’t as much a problem as you might think, as the 82° field of view is so wide that even non-eyeglass wearers have trouble seeing the whole field at once. All observers have to move their eye from side to side to take in the immense view, so vignetting in the conventional sense is not a problem. This is one of those eyepieces that can truly be described as showing you a “picture window view” of space. The visual effect of its long eye-relief and 82° apparent field is truly a full-immersion experience. Your eye is relaxed, allowing you to easily use the “averted vision” technique to study faint details across its huge 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 product 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.