Seven millimeters is the high-power eyepiece in a 1.25" barrel — the one that turns a 10-inch Dob into a planet machine. At 179x, Jupiter shows cloud belt detail, Saturn's rings show Cassini's Division as a clean gap, and the Moon becomes a landscape of craters and rilles. The usual trade-off at high power is a narrow field that makes targets hard to track, but the 82° apparent field of the 7mm UWA gives you a comfortable view with real drift time on an untracked telescope. With 17 five-star reviews — the most-reviewed eyepiece in the Astro-Tech UWA line — the owners have spoken.
The Optics
Seven elements, fully multi-coated. At 7mm, optical quality matters more than at longer focal lengths — the exit pupil is small, the magnification is high, and any weakness in the design shows up immediately. The 7mm UWA delivers a sharp, contrasty image across the center and middle zones. In fast Dobs (f/4.5–f/5), mild coma appears in the outer zone without a coma corrector — normal for any wide-field eyepiece in a fast Newtonian, and a Paracorr cleans it up completely. Cloudy Nights members rate the 7mm as one of the best performers in the UWA line. A reviewer testing in an AT102EDL f/7 apo reported stars as pinpoints across the field, with the Double Double in Lyra splitting cleanly and Izar's close companion visible — the kind of demanding targets that expose any weakness in an eyepiece.
1.25" Barrel
Fits any 1.25" focuser, diagonal, or Barlow. Safety groove engages your focuser's thumbscrew. The eyepiece is lightweight and compact — it pairs well with a 2x Barlow for extreme magnification (effectively a 3.5mm eyepiece with 82° field).
Waterproof
O-ring sealed and waterproof. Prevents internal fogging during cold planetary sessions, keeps dust and grit out of the optics, and protects the coatings from humidity and fungus.
What's Included
- Astro-Tech 7mm 82° UWA 1.25" eyepiece
- Lens caps (top and bottom)
Features
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82° apparent field of view — At high power, the wider field means more drift time on untracked telescopes and a more comfortable viewing experience than narrow-field alternatives.
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7-element fully multi-coated optics — High contrast with dark backgrounds and sharp stars. Performs well against premium competitors at several times the price.
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7mm focal length — High-power. 179x in a 1250mm Dob, 102x in a 714mm refractor, 290x in a 2032mm SCT. The planetary and lunar detail eyepiece.
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12mm eye relief — Generous for a 7mm eyepiece. Comfortable without glasses.
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Waterproof, O-ring sealed — Cold-weather performance and long-term protection.
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1.25" barrel with safety groove — Universal compatibility. Barlow-friendly.
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Lightweight — No balance concerns.
Under the Night Sky
In a 10-inch f/5 Dob at 179x, Jupiter shows the two equatorial belts with visible festoons and scalloping. The Great Red Spot shows color and shape when it transits. On the best nights, the North and South Temperate Belts emerge with hints of detail. The 82° field holds the planet for about 35 seconds of drift — long enough for meaningful observation between nudges.
Saturn at 179x shows the ring system in detail — Cassini's Division is a clean dark line, not a faint hint. The shadow of the globe on the rings is visible. Titan shows as a distinct point well separated from the planet. On steady nights, the crepe ring is visible against the globe.
The Moon at 179x is where this eyepiece is at its best. Craters show terraced walls, central peaks, and shadow detail along the terminator. Vallis Schroteri, the winding valley near Aristarchus, is resolved. The Alpine Valley shows its narrow floor. You can spend an entire session working the terminator and never feel the field is too narrow.
For deep-sky at this power, think compact objects: M57 (Ring Nebula) shows its oval ring and dark center clearly. NGC 7662 (Blue Snowball) shows its blue-green disk. Tight globular clusters like M15 resolve into stars near the core. Close double stars — Gamma Andromedae, Albireo, Epsilon Bootis — split cleanly with vivid colors. A Cloudy Nights reviewer working the 7mm in a 4-inch f/7 refractor from Bortle 8–9 skies called the Double Double in Lyra "a memorable sight that never gets old" — exactly the kind of demanding target that rewards sharp optics and comfortable eye relief.
Community Says
"A memorable sight that never gets old." This owner used the 7mm with a 2x Barlow in an AT102EDL f/7 from Bortle 8–9 skies and split the Double Double in Lyra cleanly at 200x — the kind of demanding target that exposes any weakness in an eyepiece. Izar showed its close companion embedded in the diffraction ring. — Cloudy Nights AT UWA 7mm/10mm/13mm review.
"Best deal in EPs...ever." This owner bought the full 4mm–16mm set after testing one. — Cloudy Nights AT UWA discussion.
Parfocality confirmed across the full 4mm–16mm range — this owner tested all five 1.25" UWAs and found only a small touch of the focuser needed when swapping between focal lengths. — Cloudy Nights AT 82° eyepiece review.
Observing Tip
The 7mm UWA in a 2x Barlow gives you effectively a 3.5mm eyepiece with 82° field — 357x in a 1250mm Dob. That's extreme magnification, useful only on nights of steady seeing in scopes of 10 inches or more. But when the seeing cooperates, the planetary detail is extraordinary. Use the 7mm alone first to assess the seeing. If the image is steady and sharp, drop in the Barlow for the close-up. Two eyepieces, three magnifications — the 7mm alone, plus the Barlow combinations — give you a full planetary observing toolkit from one focal length.
FAQ
How does this compare to the 7mm 100° XWA?
The 100° XWA has a wider field (100° vs. 82°), more elements (8 vs. 7), 15mm eye relief (vs. 12mm), and is heavier (17 oz vs. lightweight). The 100° XWA also has a dual 1.25"/2" barrel. The 82° UWA is lighter, simpler, and significantly less expensive. If 82° is wide enough and you don't need the extra eye relief, the UWA is excellent value. If you want the widest possible field at this focal length, the XWA is the step up.
Will coma be a problem in my Dob?
At f/4.5–f/5 without a coma corrector, you'll see mild coma in the outer 10–15% of the field. One owner confirmed this at f/5 without a Paracorr. The center and middle zones are sharp. A Paracorr or similar coma corrector eliminates the issue. At f/6 and slower, coma is negligible.
Is this parfocal with the other 82° UWAs?
Yes — confirmed by Cloudy Nights members. One owner tested all five 1.25" UWAs (4mm through 16mm) and found them parfocal, requiring only a small touch of the focuser when swapping between focal lengths.
Is 179x too much for a small telescope?
In a 6-inch scope, 179x (from a 1000mm focal length scope) is near the practical limit — usable on the steadiest nights. In a 4-inch refractor at 102x, you're at a very comfortable power for planets. The atmosphere sets the ceiling; the eyepiece just gets you there.
Final Thoughts
The 7mm UWA is the most-reviewed eyepiece in the Astro-Tech 82° line, and the reviews tell a consistent story: sharp, contrasty, wide-field views at high power for a fraction of what premium alternatives cost. It's the high-power workhorse of the UWA set — the eyepiece you pull out when the seeing steadies and the planets are waiting. At 1.25", 7 elements, and this price point, there isn't much else that delivers this combination of performance, field width, and value.
