This Explore Scientific 28mm argon-purged is a substantial 2" eyepiece that gives impressively sharp and contrasty wide field views of nebulas, compact open clusters, globular clusters, etc. with virtually any telescope that can use 2" eyepieces.
This new 68° 28mm Explore Scientific is a high-quality low to medium power wide field 2" 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 2" 28mm Explore Scientific is designed for the serious deep space explorer - no matter what your telescope type. The calculator in the "formula" tab above will show you just how wide the field will be with your particular telescope. For example, the 28mm Explore Scientific will give you a 0.95 degree field at 71x with the 2000mm focal length of either a big 17.5" f/4.5 Dobsonian or an 8" f/10 Schmidt-Cassegrain. That's almost two lunar diameters and is ideal for observing emission and reflection nebulas and nebula remnants.
While it's particularly well-suited for use with Dobsonians (it provides a huge 6.2mm exit pupil for rich field observing on an f/4.5 scope, close to the maximum usable), it can provide "picture window onto space" images with any telescope that can use a 2" eyepiece. With a short focal length refractor such as the TeleVue TV-85, for example, it will give you a huge 3.17° field at 21x. This eyepiece would be a welcome addition to any serious eyepiece collection.
The eye relief of this six lens/fully multicoated is an excellent 22mm. That means that this 28mm Explore Scientific can be used by most eyeglass wearers with no vignetting of the 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
