William Optics 40mm 2″ SWAN Eyepiece: a window to space
The William Optics SWAN 40 mm is a 2-inch wide-field eyepiece with an apparent field of view of 72 degrees. The combination of long focal length and wide field provides the largest possible patch of sky in a single view: extended nebulae, star fields, and the Milky Way at their finest.
The five-element design is multi-coated and the lens edges are blackened to prevent stray light. With 28 mm of eye relief, viewing is comfortable, even with glasses, and the fold-down eyecup can be adjusted to your preferred viewing position. The filter thread accepts 2-inch filters directly.

Which telescopes
The eyepiece requires a 2-inch focuser or diagonal. On telescopes with a slow f-ratio, the field performs at its tightest; on very fast optics, edge stars become softer, which is typical for this price range.
Featured accessories
Combine the eyepiece with the Dura Bright 2-inch diagonal for the complete visual overview package.
For whom yes and for whom no
- ✓ Deep-sky observers looking for maximum field of view
- ✓ Glasses wearers, thanks to 28 mm eye relief
- ✗ Owners of 1.25-inch connections only
Specifications
| Focal length | 40 mm |
| Apparent field of view | 72 degrees |
| Optics | 5 lenses, multi-coated, blackened edges |
| Eye relief | 28 mm |
| Mount | 2 inch, with filter thread |
| Eyecup | Foldable |
You can find more accessories for this merk at the William Optics merk Page.





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