The first time you swap out a standard Plossl for the 28mm UWA, the difference hits you immediately. The field opens up from 50° to 82° — nearly three times the area of sky — and objects that were cropped at the edges of a Plossl now sit comfortably inside the view with star field to spare. This is the eyepiece that turns a 10-inch Dob into a deep-sky scanner: drop it in, point at the Milky Way, and start moving. Nebulae, open clusters, and galaxy groups drift through an 82° panorama that's sharp, contrasty, and wide enough to show context.
The Sweet Spot
An 82° apparent field sits in a practical middle ground. It's wide enough to be immersive — you're inside the star field, not looking at it through a window. But it doesn't require the 9-element optical complexity of a 100° design, which means fewer glass surfaces, higher contrast, and a lighter price. The 28mm UWA uses 7 elements, fully multi-coated — and the light transmission is exceptional: independent measurements on Cloudy Nights show RGB transmission of 94/96/98%, with the actual apparent field measuring 83.3° and actual focal length at 28.5mm. The result is a wide-field eyepiece with high contrast and good edge correction that doesn't cost as much as the premium ultra-wides — and doesn't weigh as much either, though at 24 ounces it's still a substantial piece of glass.
Where It Shines
In a 10-inch f/5 Dob (1250mm focal length), the 28mm UWA gives you 45x with a 1.8° true field. That's wide enough to frame the entire Orion Nebula complex, both clusters of the Double Cluster simultaneously, or the Pleiades with surrounding star field. In an 8-inch f/10 SCT, it runs 51x with a 1.6° true field — the low-power, wide-field eyepiece that many SCT owners are missing from their collection. In a short-focal-length refractor like the AT66EDQ at 390mm, it delivers 14x with a 5.8° field — a rich-field sweeper for the Milky Way.
Eye Relief
Eye relief is 12mm. That's comfortable for most observers without glasses but tight for eyeglass wearers. If you observe without glasses, 12mm provides a stable, comfortable eye position. With glasses, you'll lose a portion of the outer field. For observers who need full-field eyeglass compatibility, consider the 20mm XWA (15mm eye relief, 100° field) as an alternative, though at higher magnification and a different price point.
2" Barrel Only
The 28mm UWA fits 2" focusers only. The field stop on a 28mm, 82° eyepiece is physically too large for a 1.25" barrel. A safety groove is machined into the barrel to engage your focuser's thumbscrew.
Waterproof
O-ring sealed and waterproof. Prevents internal fogging at cold temperatures, keeps dust out, and protects the internal coatings from humidity over the life of the eyepiece.
What's Included
- Astro-Tech 28mm 82° UWA 2" eyepiece
- Lens caps (top and bottom)
Features
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82° apparent field of view — Nearly three times the sky area of a 50° Plossl. Wide enough to be immersive, efficient enough to keep the element count and price reasonable.
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7-element fully multi-coated optics — Fewer elements than 100° designs means higher contrast. The image is sharp and contrasty across the usable field.
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28mm focal length — Low power, wide field. 45x in a 1250mm Dob, 51x in an SCT, 14–25x in short refractors. The finder-replacement eyepiece for deep-sky scanning.
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12mm eye relief — Comfortable without glasses. Tight for eyeglass wearers.
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Waterproof, O-ring sealed — Cold-weather performance, dust resistance, long-term optical protection.
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2" barrel with safety groove — Secure connection. The groove engages your focuser thumbscrew.
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24 ounces — Substantial. Check balance on lightweight scopes before observing.
Under the Night Sky
In a 10-inch f/5 Dob at 45x, this is the eyepiece that shows you the neighborhood. The Orion Nebula isn't just M42 — it's M42, the Running Man nebula, the surrounding OB association, and the entire Sword region in one field. The Pleiades show all the bright members plus the fainter outliers, with reflection nebulosity visible on transparent nights. The Double Cluster sits in the center of the field with chains of stars connecting the two clusters, exactly as they look in photographs.
Point it at the heart of the Virgo Cluster and you can catch three or four galaxies in a single field — M84 and M86 flanking each other, with NGC 4388 nearby. In Sagittarius, the Lagoon and Trifid are close enough to frame together. The Milky Way in Cygnus is a river of resolved stars with dark lanes winding through it. One experienced Cloudy Nights observer using a 16-inch f/4.4 Dob with a Paracorr turned the 28mm UWA on M81, M82, and NGC 3077 — all three galaxies big and bright in a single field — and described the view as jaw-dropping and totally immersive. That's the kind of experience a wide-field, high-contrast eyepiece delivers in a large Dob: galaxy groups become landscapes, not catalog entries.
For Dobsonian owners, the low magnification and wide field make this an effective star-hopping eyepiece. The 1.8° true field overlaps well with typical finder fields, so the transition from finder to eyepiece is smooth — what you see in the finder, you see in the eyepiece, just brighter and sharper.
Community Says
"The three galaxies (M81, M82, and NGC 3077) big, bright — it doesn't get any better. Jaw dropping, totally immersive, mind blowing."
— Cloudy Nights AT 28mm UWA discussion. This owner was observing with a 16-inch f/4.4 Dobsonian and Paracorr, and found the 28mm UWA delivered a galaxy group view he described in superlatives.
"The AT 28mm UWA is one of the very best deals in astronomy today."
— Cloudy Nights UWA Eyepieces discussion.
Observing Tip
Pair this eyepiece with a broadband light-pollution filter (UHC or similar) for deep-sky work from suburban skies. At 45x in a 10-inch Dob, the exit pupil is about 5.6mm — large enough that a UHC filter significantly improves the contrast on emission nebulae without dimming the star field excessively. The California Nebula, the Rosette Nebula, and the North America Nebula all become visible targets from Bortle 5–6 skies with this combination.
FAQ
Will this fit a 1.25" focuser?
No. The 28mm UWA is 2" barrel only. If your scope only accepts 1.25" eyepieces, look at the 16mm or shorter UWAs in the Astro-Tech line, which fit 1.25" focusers.
How does this compare to the 20mm 100° XWA?
Different tools for different jobs. The 28mm UWA gives lower magnification and a wider true field (more sky in the view) with an 82° apparent field. The 20mm XWA gives higher magnification and a narrower true field but with a 100° apparent field that feels more immersive. The 28mm is the better deep-sky scanner and star-hopper. The 20mm is the better immersive deep-sky eyepiece for objects that fit within its field.
Is 12mm eye relief a problem?
For observers without glasses, no — 12mm is comfortable for extended sessions. For eyeglass wearers, it's tight. You can still see through the eyepiece with glasses, but you'll lose some of the outer field. If full-field eyeglass use is important, look at the XWA line (15mm eye relief across all focal lengths).
Can I use this as a finder replacement?
In short-focal-length scopes, yes. At 14x in a 390mm refractor or 25x in a 700mm scope, the true field is wide enough (3–6°) to overlap with your finder, making the transition seamless. In longer-focal-length scopes (1250mm+), the true field narrows to 1.8° — still wide, but not a finder replacement.
Final Thoughts
The 28mm UWA has earned its five-star reviews for a straightforward reason: it delivers wide-field, high-contrast views of deep-sky objects at a price that doesn't require justification. People have described it as the eyepiece they reach for first every session. On Cloudy Nights this eyepiece has generated a 33-page discussion thread. At 82°, the field is wide enough to change how you observe — you stop looking at objects through a tube and start scanning the sky. If you own a telescope with a 2" focuser and you don't have a wide-field, low-power eyepiece, this is where to start.
