Product Description
This 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.
Tech Details
| Barrel Size | 1.25" |
|---|---|
| Eye Relief | 12mm |
| Field of view | 82 |
| Focal Length | 4mm |
| Number of optical elements | 7 |
| Weight | 6.5 ounces |
| Warranty | 1 year |
Reviews
At 201X this eyepiece performed very well and the resolution I received was great. The eye relief at this f/l was quite comfortable and I experienced no black out. Images were sharp to the edges and all in all this is an exceptional eyepiece at an exceptional price. One thing I will say however is that this entire series of EP'S seems to be very sensitive to seeing conditions. I say this because I used it last night and all was well but in earlier tests with less than desirable conditions, this eyepiece suffered from a lot of ghosting and flaring. So beware of this fact.
In summary, for the price it can't be beat and it is a fine addition to my collection. (Posted on 12/28/2022)