Eyepieces & Optics
Wide-Field Eyepiece
60° to 100° of apparent field — the whole object, with room around it.
Specifications
| Focal lengths | 3.5 – 31 mm |
|---|---|
| Apparent field | 68°, 82° or 100° |
| Eye relief | 13 – 22 mm |
| Elements | 6 – 8 in 4 – 5 groups |
| Barrel | 1.25″ and 2″ |
| Weight | 200 – 1000 g |
Observing parameters
| True field (31 mm, 82°, f/5) | ≈ 2.6° |
|---|---|
| True field (13 mm, 82°, f/5) | ≈ 1.1° |
| Best for | open clusters, large nebulae, galaxies |
| Glasses-friendly | yes on most 68° and 82° designs |
| Exit pupil at f/5, 31 mm | 6.2 mm |
Overview
A wide-field (or ultra-wide / "nagler-style") eyepiece uses six to eight elements to hold sharpness out to 68°, 82° or even 100° of apparent field. The practical effect is that large objects stop being framed by the field stop: the Pleiades, the Andromeda Galaxy and the Veil all fit at once, with sky to spare.
They cost several times a Plössl and weigh more, and the very widest designs are heavy enough to shift focus on a marginal focuser. Long eye relief is standard, which makes them usable with glasses — a real advantage if you have astigmatism.
One good wide-field low-power eyepiece is the highest-value purchase in this entire category.
Where it fits
Practical notes
- Check the weight against your focuser — a 1 kg eyepiece will sag a single-speed rack-and-pinion.
- A wide field at low power is a legitimate substitute for a larger telescope on big, faint objects.
- Parfocal sets save refocusing when you swap eyepieces, which matters at high power.
- The widest designs show some astigmatism at the very edge on fast telescopes; that is normal, not a defect.
Pairs with
Related tools
Plössl Eyepiece
The symmetric four-element default — clean, cheap, and honest about its limits.
Eyepieces & Opticsobserving
Barlow Lens
A diverging lens that multiplies the effective focal length of everything behind it.
Eyepieces & Opticsobserving
Refractor Telescope
A lens at the front, an eyepiece at the back — the simplest and most robust optical path.
Telescopes & Mountssetup