GSO Moon filter 1.25″
If you have ever tried to observe a full Moon through a larger telescope, you know exactly what we mean - a blinding glare that forces you to squint and causes eye fatigue within minutes. That is precisely why lunar filters exist. The GSO Moon 1.25″ eyepiece filter is a simple yet highly effective accessory that should be part of every observer's kit.
How does it work?
The filter threads directly into the standard 1.25″ eyepiece barrel and works on the principle of neutral attenuation - it reduces the total amount of light passing through the eyepiece without significantly altering the colour rendition of the scene. The result is a pleasantly dimmed view of the lunar surface with noticeably improved contrast.
Craters, mountain ranges, maria and fine rilles stand out in much greater relief, because the eye is no longer overwhelmed by excessive light intensity and can resolve fine details in the transitional zones around the terminator. The reduced brightness also allows you to extend comfortable visual observation sessions without straining your eyes - something that observers who enjoy spending extended time at the eyepiece and systematically mapping the lunar surface will particularly appreciate.
The filter is effective not only during the full Moon but also in other phases when the Moon is high above the horizon and its brightness is still considerable.
Construction and compatibility
The GSO Moon 1.25″ filter is mounted in a standard metal threaded ring that fits all eyepieces and diagonals with a 1.25″ barrel diameter. The optical element consists of a glass disc with a semi-transparent coating that provides uniform light attenuation across the entire surface. The glass is polished on both sides and treated with an anti-reflection coating that minimises stray reflections and ghost images. Installation and removal are quick and require no tools - simply thread it in.
Compatible telescope types
- Refractors
- Reflectors
- Catadioptric systems (SCT, Maksutov)
In short - any telescope equipped with 1.25″ eyepieces.
Who is this filter for?
- Beginners who are just discovering the beauty of the lunar surface and want to enjoy observing without discomfort.
- Experienced observers working with larger apertures from 100 mm upwards, where the Moon's brightness is especially intense.
- Anyone who wants a low-cost accessory with an immediate and clearly visible benefit for visual astronomy.
A great first step into the world of eyepiece filters
The lunar filter is also an excellent introduction to eyepiece filters in general - its effect is immediately apparent and the result will convince any observer at first glance. If you are looking for an affordable accessory that makes a real and noticeable difference to visual astronomy, the GSO Moon lunar filter is exactly the right choice.
Specifications
| Parameter |
Value |
| Filter diameter |
1.25″ |
| Thread type |
Standard 1.25″ eyepiece thread |
| Filter type |
Neutral density (neutral attenuation) |
| Housing material |
Metal |
| Optical coating |
Anti-reflection coating on both sides |
| Recommended use |
Lunar observation - all phases |
| Recommended aperture |
From 60 mm, especially effective from 100 mm upwards |
