You may be startled at the amazingly wide expanse of inky black sky that greets you when you first look into the 92° field of this Explore Scientific 17mm hyper-wide eyepiece. Observing with the 17mm Explore 92° feels more like you are in orbit above the Earth, taking a space walk, rather than looking through a telescope eyepiece.
The Explore Scientific 2" 17mm 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 92° 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.
With an apparent field of view that is close to the maximum possible for a hyper-wide eyepiece design, celestial objects are easier to locate with the Explore 92°. In non-driven telescopes, like Dobsonians or altazimuth mount refractors, an object stays in the field of view for a long time before you need to nudge the scope to center it again.
The 17mm 92° field Explore Scientific is O-ring sealed and argon-purged to be 100% waterproof. This prevents internal fogging in the eyepiece in cold weather; 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 lens elements.
The latest computer design programs have been used to optimize its performance. Its eight element/six 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 92° field of view. The lens edges have been blackened to improve contrast.
A 10" f/4.5 Dobsonian reflector has a full 1.37° field at 67x with this eyepiece, able to encompass all of the Pleiades in one field. Even an 8” f/10 catadioptric has a field more than 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.
The long 20mm eye relief of the Explore Scientific 92° will not vignette the field of view for eyeglass wearers. The eyepiece has a soft fold-down rubber eyecup for eyeglass use and comes with dust covers for both ends of the eyepiece.
This individually serial numbered 17mm Explore Scientific 92° field 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