Sky-Watcher Plossl SWA 25mm 58° 1.25″ Eyepiece
Overview
The Sky-Watcher Plossl SWA 25mm eyepiece is a popular choice among astronomers of all experience levels. Thanks to its wide 58° apparent field of view, it delivers a broad, immersive view of the night sky, making it easy to observe large objects such as open star clusters, nebulae, and the full disc of the Moon. The hybrid Plossl optical design ensures sharp, high-contrast images across the entire field, from center to edge.
With a standard 1.25″ barrel diameter, this eyepiece is compatible with the vast majority of telescopes available on the market - including refractors, reflectors, and catadioptric telescopes.
Optics and Coatings
The optical system consists of 5 lens elements in 3 groups, which is characteristic of a modern hybrid Plossl design. All optical surfaces feature Fully Multi-Coated (FMC) optics, which significantly reduces unwanted reflections and maximises light transmission. The result is a bright, high-contrast, and detailed image - even under low-light conditions.
FMC coatings are particularly valuable when observing faint deep-sky objects such as distant galaxies and nebulae, where every photon counts. The eyepiece is also designed to minimise spherical and chromatic aberrations, even towards the edges of the field of view.
The exit pupil diameter is 16mm, making observation comfortable for eyeglass wearers as well as those without.
Build Quality and Design
The body of the eyepiece is solidly constructed and well-finished. At 72mm in length and 172g in weight, it is robust yet light enough to be practical for regular use. The maximum body diameter is 44mm.
The eyepiece features a height-adjustable, twist-up rubber eyecup that provides a comfortable eye rest and blocks stray ambient light. The adjustable rubber eyecup is especially convenient for observers who wear glasses - it can be rolled down to reduce the eye relief distance and allow comfortable viewing without removing spectacles.
The standard 1.25″ barrel ensures compatibility with virtually all focusers currently available on the market.
Technical Specifications
| Parameter |
Value |
| Focal length |
25mm |
| Apparent field of view |
58° |
| Barrel diameter |
1.25″ |
| Optical design |
Hybrid Plossl (SWA) |
| Lens elements / groups |
5 elements / 3 groups |
| Optical coatings |
Fully Multi-Coated (FMC) |
| Field stop diameter |
25.3mm |
| Exit pupil diameter |
16mm |
| Overall length |
72mm |
| Maximum body diameter |
44mm |
| Weight |
172g |
| Eyecup |
Adjustable twist-up rubber eyecup |
Who Is This Eyepiece For?
The Sky-Watcher Plossl SWA 25mm is an ideal choice for both beginners and more experienced amateur astronomers looking for a reliable, everyday eyepiece. It performs well for:
- Planetary observation - Moon, Jupiter, Saturn, Mars
- Deep-sky objects - nebulae, galaxies, star clusters
- Wide-field scanning of the Milky Way
- General daytime terrestrial use
Its universal 1.25″ barrel makes it compatible with virtually all refractors, Newtonian reflectors, Dobsonians, and Schmidt-Cassegrain or Maksutov telescopes. This eyepiece is recommended for anyone who wants to improve the comfort and quality of their astronomical observations without investing in the most expensive premium optics.
