Sky-Watcher Plossl SWA 4mm 58° 1.25″ Eyepiece
Overview
The Sky-Watcher Plossl SWA 4mm wide angle eyepiece is a premium astronomical eyepiece designed for observers who demand high performance during planetary and detailed visual observation. The 58° apparent field of view delivers a natural and immersive visual experience, making it easy to track objects even at high magnification. Thanks to a hybrid five-element Plossl optical design arranged in three groups, this eyepiece produces an exceptionally sharp and high-contrast image across the entire field of view. It is suitable for both beginners and experienced astronomers who value quality craftsmanship and reliable optics.
Optical Design and Coatings
The hybrid Plossl optical system combines the proven principles of classic Plossl construction with modern refinements that minimize chromatic aberrations and increase light transmission. All optical surfaces are treated with Fully Multi-Coated (FMC) broadband coatings, which maximize light throughput while suppressing unwanted reflections and ghosting artifacts. The result is a bright, sharp, and high-contrast image with excellent reproduction of fine detail - whether you are observing the surface of the Moon, planetary features, or close double stars. The 4mm focal length with FMC coatings makes this eyepiece one of the most popular choices for high-magnification planetary work.
Comfort and Eye Relief
The height-adjustable rubber eyecup provides comfortable viewing for observers with and without eyeglasses. The eyecup is twist-up and continuously adjustable, allowing each observer to fine-tune the position to their individual needs. An eye relief of 16mm enables relaxed observation without uncomfortable pressure on the eye and helps maintain a stable eye position relative to the eyepiece. This feature is especially appreciated during extended observing sessions.
Compatibility and Build Quality
The eyepiece features a standard 1.25″ barrel diameter, making it compatible with the vast majority of astronomical telescopes on the market. The Sky-Watcher SWA 4mm 1.25″ eyepiece can be used with refractors, reflectors, and catadioptric telescopes without any adapters. With a compact length of 90mm and a weight of 184g, the eyepiece is pleasantly balanced and does not put unnecessary strain on the telescope or focuser. It is an ideal choice for observing planets, the Moon, double stars, and fine detail in globular clusters.
Key Applications
- Planetary observation - Moon, Mars, Jupiter, Saturn and more
- Lunar surface detail and crater exploration
- Double star splitting at high magnification
- Fine detail in globular star clusters
- Travel and field use thanks to compact dimensions
Specifications
| Parameter |
Value |
| Focal Length |
4mm |
| Apparent Field of View |
58° |
| Barrel Diameter |
1.25″ |
| Optical Design |
Hybrid Plossl - 5 elements in 3 groups |
| Coatings |
Fully Multi-Coated (FMC) |
| Eye Relief |
16mm |
| Eyecup |
Twist-up adjustable rubber eyecup |
| Length |
90mm |
| Weight |
184g |
| Accessories Included |
Protective lens caps |
Why Choose the Sky-Watcher SWA 4mm?
This eyepiece represents an outstanding price-to-performance ratio for anyone who wants to get the most out of their telescope during detailed observation. Elevate your astronomical experience with the combination of premium FMC optical coatings, a comfortable adjustable eyecup, and a proven hybrid Plossl construction. The eyepiece is supplied with protective lens caps and is ready to use straight out of the box. Its compact dimensions and robust build make it equally well suited to travel and stationary observatory use.
