Sky-Watcher WA-66 20mm 66° 1.25″ wide-angle eyepiece
Looking for an eyepiece that gives you a wide, comfortable view of the night sky without spending too much? The Sky-Watcher WA-66 20mm wide-angle eyepiece with a 66° apparent field of view is exactly that choice. It combines a proven optical design, quality construction, and practical features that make it a great fit for both beginners and experienced amateur astronomers.
Optics and build quality
The eyepiece uses a 5-element optical design with multi-layer anti-reflection coatings on all optical surfaces. This maximizes light transmission, reduces glare, and produces an image that looks vivid and contrasty. The body is fully metal, and the lenses are made of glass - no plastic compromises here. The 1.25″ barrel has a standard filter thread, so you can attach any 1.25″ filter without adapters.
Comfortable viewing for everyone
The generous eye relief means you do not need to press your eye close to the eyepiece - viewing is comfortable even if you wear glasses. The fold-down rubber eyecup lets you quickly adjust the distance to suit you and effectively blocks unwanted ambient light.
Wide field of view - a real advantage
A 66° apparent field of view clearly surpasses classic Erfle and standard Plossl eyepieces, bringing you close to premium territory. With a 20mm focal length and a typical telescope, the true field of view is wide enough to let star clusters, nebulae, and planets feel like they have room to breathe.
Image correction is surprisingly good for telescopes down to f/6. The image holds up well toward the edges of the field, without the noticeable coma that troubles cheaper wide-angle eyepieces. In terms of quality, this eyepiece matches well-regarded SWA-58° types, while offering a full 8° more field of view.
Who is this eyepiece for?
The Sky-Watcher WA-66 20mm is ideal as your first truly wide-field eyepiece. It works excellently for:
- Finding objects in the sky
- Sweeping through the Milky Way visually
- Observing large nebulae and open star clusters
It makes an excellent upgrade or replacement for the eyepiece that came with your telescope, taking your observing experience to the next level without a large investment. It is suitable for refractors and reflectors with a focal ratio of f/6 or higher.
Summary
Overall, this is a solid, well-thought-out eyepiece that delivers real value for its price. If you are looking for a reliable and versatile companion for the night sky, the WA-66 20mm will not disappoint you.
Technical specifications
| Parameter |
Value |
| Focal length |
20mm |
| Apparent field of view |
66° |
| Barrel diameter |
1.25″ |
| Optical design |
5-element wide-angle |
| Coatings |
Multi-layer anti-reflection on all surfaces |
| Body material |
Metal |
| Filter thread |
Standard 1.25″ |
| Eyecup |
Fold-down rubber |
| Recommended focal ratio |
f/6 and higher |
