The 13mm is the transition point — high enough magnification to show real detail in globular clusters and planetary nebulae, low enough to hold a useful true field for open clusters and galaxy groups. In a 10-inch f/5 Dob, it gives you 96x and just under a degree of sky in the eyepiece. In an f/7 refractor, 55x with 1.5° of field. The 82° apparent field wraps around the view in a way that standard eyepieces can't match, and the 7-element design keeps contrast high while staying light enough to fit any 1.25" focuser without shifting the balance.
The Optics
Seven elements, fully multi-coated. The 82° UWA design balances field width against optical complexity — wide enough to be immersive, simple enough to maintain high contrast with minimal scatter. The image is sharp across the center and middle zones with well-controlled astigmatism and field curvature. One owner bought a pair for binocular telescopes and calls them "mainstays." Cloudy Nights members rate the 13mm as sharper to the edge than the 16mm in fast scopes, with one reviewer calling it and its siblings "very sharp" in an AT102EDL f/7 apo — the Moon showed beautiful crispness, and double stars like Izar split cleanly with the blue companion embedded in the diffraction ring at 200x with a Barlow.
1.25" Barrel
Fits any 1.25" focuser, diagonal, or Barlow. A safety groove is machined into the barrel to engage your focuser's thumbscrew. The eyepiece is lightweight — it won't change the balance on any telescope.
Waterproof
O-ring sealed and waterproof. Prevents internal fogging at cold temperatures, keeps dust out, and protects the internal coatings over the life of the eyepiece.
What's Included
- Astro-Tech 13mm 82° UWA 1.25" eyepiece
- Lens caps (top and bottom)
Features
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82° apparent field of view — Nearly three times the area of a standard 50° Plossl. Wide enough to show targets in their surrounding context.
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7-element fully multi-coated optics — High contrast, controlled scatter, good edge correction.
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13mm focal length — Mid-power versatility. 96x in a 1250mm Dob, 55x in a 714mm refractor, 156x in a 2032mm SCT. Works on nebulae, clusters, galaxies, and planets.
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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 and long-term optical protection.
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1.25" barrel with safety groove — Universal compatibility. Thumbscrew retention.
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Lightweight — No balance issues on any telescope.
Under the Night Sky
In a 10-inch Dob at 96x, M13 resolves individual stars across its face — not just at the edges, but threading into the core. M57, the Ring Nebula, shows its oval shape clearly with the central hole defined. The Orion Nebula at this power shows the Trapezium cleanly split against the bright nebulosity, with the wings extending well beyond. A Cloudy Nights reviewer using an AT102EDL f/7 in Bortle 8–9 skies reported the Beehive Cluster as an impressive sight, fitting comfortably inside the 82° field at 55x — the kind of target that rewards a wide field by showing the cluster in its full context against the surrounding star field.
Jupiter shows both equatorial belts with hints of festoons on steady nights. Saturn's rings are separated from the globe with Cassini's Division visible. The 82° field gives you comfortable drift time on an untracked Dob — roughly 40 seconds before a planet exits the view at this magnification.
In a short refractor at 55x, the field is wide enough for open clusters like M35, M37, and the Double Cluster. Galaxy groups in Virgo and Leo show multiple members in a single field. The sky background is dark enough to bring out faint nebulosity on the Veil and the North America with a filter.
Community Says
"All three UWAs are very sharp." This owner tested the 7mm, 10mm, and 13mm in an AT102EDL f/7 from Bortle 8–9 skies and found the 13mm delivered beautiful crispness on the Moon and split Izar cleanly at 200x with a Barlow — the blue companion embedded in the diffraction ring. The Beehive at 55x filled the 82° field and showed the cluster in full context against the surrounding star field. — 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.
Observing Tip
The 13mm UWA makes a natural partner for the 7mm UWA — one gives you the mid-power survey view, the other zooms in for detail. Together they cover the range from deep-sky scanning to planetary close-ups, and both fit a 1.25" focuser without adapters. Add the 10mm to split the difference, and you have a three-eyepiece set that handles virtually any target from any telescope.
FAQ
How does this compare to the 13mm 100° XWA?
The 100° XWA has a wider apparent field (100° vs. 82°), more elements (9 vs. 7), is waterproof (both are), has 15mm eye relief (vs. 12mm here), and is heavier (19 oz vs. lightweight). The XWA is the premium option. The 82° UWA is the lighter, more affordable choice that still delivers a wide field with high contrast. If 82° is wide enough for your needs, the UWA gives you excellent performance at a lower price.
Is this parfocal with the other 82° UWAs?
The Astro-Tech 82° UWA eyepieces are close to parfocal with each other. You'll need only a small focus adjustment when swapping between focal lengths in the line.
Can I use this in a binoviewer?
Yes. One owner bought a matched pair for binocular telescopes and rates them highly. The 1.25" barrel and lightweight construction make them well suited for binoviewer use.
Will this work in a fast Dobsonian?
Yes. The optical design handles fast focal ratios well. At f/4.5–f/5, you may see some softening in the last 10% of the field — normal for any 82° eyepiece at fast ratios. A coma corrector like a Paracorr will clean up the outer field if it bothers you.
Final Thoughts
The 13mm UWA is the middle of the 82° line — the focal length that does a bit of everything without specializing in anything. It resolves globular clusters, shows planetary detail, frames open clusters in context, and holds a useful field on galaxies. At 1.25", 7 elements, and a lightweight build, it fits any telescope and any budget. Fourteen five-star reviews and an owner who bought two for binocular use tell the story: this eyepiece delivers more than its price suggests, and it works reliably session after session.
