Astro-Tech 4mm UWA 82° 1.25" Eyepiece

This 4mm Astro-Tech 82° field eyepiece is an excellent very high power, very wide field eyepiece for resolving globular clusters and closely-spaced binary stars .  The 82° 4mm Astro-Tech UWA eyepiece is an excellent short focal length/ultra wide field eyepiece with an outstanding price.

The optical designers used the latest computer design programs to optimize its performance. Its seven 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 a very wide 82° field of view. The lens edges have been blackened to improve contrast.

The 4mm 82° Astro-Tech works with any telescope from a fast focal ratio reflector to a long focal length refractor or Maksutov. It's particularly good with Dobsonians and fast focal ratio refractors, providing high magnification with a very wide field of view for observing smaller globular clusters and compact nebulas.

At 12mm, the eye relief is good for such a short focal length eyepiece, although eyeglass wearers will still see a somewhat vignetted image. 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. This is an eyepiece that shows you a "picture window view" of space for a true full-immersion observing experience. With its unconstricted view, your eye relaxes, allowing you to easily use the "averted vision" technique to study faint details across a huge field of view.

The eyepiece has a soft fold-down rubber eyecup and comes with dust covers for both ends of the eyepiece.