GSO Super Plössl 4mm 52° 1.25″ eyepiece
Looking for an eyepiece that lets you squeeze the maximum magnification out of your telescope and reveals planets in the finest detail? The GSO Super Plössl 4mm eyepiece is a classic choice for observers who want a reliable, optically sound short focal length eyepiece at a reasonable price. Its 4mm focal length makes it one of the highest-performing eyepieces in any amateur astronomer's standard kit.
Optical design and image quality
The Super Plössl design is a proven and well-established standard among planetary eyepieces. This eyepiece uses a symmetric four-element arrangement in two groups, which delivers excellent correction of chromatic aberration and image distortion across the entire field of view. The 52° apparent field of view is typical for the Plössl design and, at such a short focal length, provides a comfortable, sharp image at the center of the field - exactly where you spend the vast majority of your time during planetary observation.
All optical surfaces are fully multi-coated with anti-reflection coatings that minimize light loss and stray reflections, keeping image contrast as high as possible.
Construction and compatibility
The eyepiece comes with a standard 1.25″ filter thread, so you can easily combine it with a lunar, polarizing or planetary filter without any additional adapters. The design also supports connection of a camera via an optional camera adapter - making the eyepiece suitable not only for visual observation but also for basic afocal projection when photographing planets or the Moon. The 1.25″ barrel fits without any issues into the standard focuser of the vast majority of telescopes on the market.
Who is this eyepiece for?
The short 4mm focal length makes this eyepiece an ideal tool for anyone who wants to achieve high magnification when observing the Moon, solar system planets or double stars. It suits both beginners building their first eyepiece set who need a reliable "planetary" eyepiece at the high-magnification end of the focal length range, and more experienced observers looking for an affordable backup to their premium eyepieces.
The eyepiece performs best in combination with a telescope of medium to long focal ratio (f/8 and above), where the Plössl design delivers its best results and edge aberrations are minimal.
About GSO
GSO is an established manufacturer of astronomical optics with a long tradition and a solid reputation for value for money. Their Super Plössl series provides a reliable foundation for any observer's kit bag. Reliable optics, standard mechanical dimensions and an accessible price are the reasons these eyepieces repeatedly appear in recommendations for both beginner and advanced astronomers around the world.
Key specifications
| Parameter |
Value |
| Focal length |
4mm |
| Apparent field of view |
52° |
| Barrel diameter |
1.25″ |
| Optical design |
Super Plössl (4 elements in 2 groups) |
| Coatings |
Fully multi-coated (FMC) |
| Filter thread |
1.25″ standard |
| Camera connection |
Via optional camera adapter |
| Recommended focal ratio |
f/8 and above |
| Primary use |
Planetary and lunar observation, double stars |
Main advantages at a glance
- Short 4mm focal length for maximum magnification
- Fully multi-coated optics for high contrast and minimal light loss
- Standard 1.25″ barrel and filter thread - no adapters needed
- Compatible with optional camera adapter for afocal photography
- Suitable for beginners and experienced observers alike
- Reliable GSO quality at an affordable price
