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Astro-Tech 4mm UWA 82° 1.25" Eyepiece

Regular Price: $119.95

Special Price $99.95

Availability: In stock

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 . . .
Our Product #: ATUWA04
Astro-Tech Product #: ATUWA04

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


Review by:
I have had this EP for about a month now and have used it about five times and I really wanted to wait until I got a solid impression of it. My test bed was my AT115EDT and my targets have been the Moon, Jupiter and Saturn.

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)
Review by:
I have mainly used this 4mm in my AT80ED and it has provided a great high power, wide field view. I was wanting something that was higher magnification then my 5.5mm EP and had wider field of view. When i seen the AT UWA series was in stock I thought I would give this eyepiece a try for the price, it has not disappointed. (Posted on 6/26/2022)
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