Eyepiece Omegon Cronus WA 4mm 60° 1.25″

Omegon Cronus WA 4mm 60° 1.25″ eyepiece

Some eyepieces simply work - and then there are eyepieces that keep you outside long into the night because you just don't want to stop observing. The Omegon Cronus belongs to the second category. Designed to be affordable and easy to use, it still delivers optical performance that more experienced observers will appreciate. The 4mm focal length makes this a high-magnification tool - ideal for detailed views of planets and double stars.

Wide apparent field of view

The 60° apparent field of view is significantly wider than that of classic Kellner-type eyepieces, which typically offer around 40-45°. In practice, this means you see approximately one-third more sky at once - and at the high magnification of a 4mm eyepiece, you will especially appreciate this when following planetary detail or keeping an object centered in the field.

Comfortable eye relief - no kidney bean effect

The 16mm eye relief is an above-average value for an eyepiece of this type, ensuring comfortable eye placement without unpleasant vignetting or dark shadows at the edges of the field.

The absence of these shadows - known as the kidney bean effect - is one of the practical strengths of the Cronus series. Many other eyepieces suffer from the problem that even the slightest movement of the head causes a dark patch to obscure the field of view. In the Cronus, this effect is reduced to a minimum, so observing remains smooth and comfortable even when you look slightly off-centre.

Anti-reflection coatings for high contrast and sharpness

All air-to-glass surfaces are coated with anti-reflection layers that minimise unwanted reflections and light scatter. The result is high contrast and a sharp image - critical qualities when observing planets, where every detail matters. The Omegon Cronus WA 4mm eyepiece therefore gets the maximum performance from your telescope's optics, whether it is a refractor, reflector or catadioptric system.

Practical features and compatibility

• Twist-up eyecup - fold it down for observers without glasses, or keep it extended to maintain the correct eye relief for eyeglass wearers
• Standard 1.25″ barrel - compatible with the vast majority of telescopes on the market
• 1.25″ filter thread - accepts planetary or UHC filters without any adapters
• Suitable for use with a binocular viewer

What can you observe with the 4mm focal length?

With a 4mm focal length and a typical telescope of 900mm focal length, you achieve a magnification of 225x - sufficient for observing the Great Red Spot on Jupiter, the Cassini Division in Saturn's rings, or surface details on Mars at opposition. Beyond the solar system, this eyepiece is well suited to compact globular clusters and close double stars. High magnification for planetary observation is precisely what this eyepiece was designed for.

Part of a complete eyepiece set

If the Cronus appeals to you, you will be pleased to know that the entire series is available in eight different focal lengths, with fine steps especially in the shorter focal length range. Having a complete set of eyepieces from the same optical family delivers consistent colour rendering, contrast and observing feel across all magnifications - from wide overview fields right through to maximum zoom.

The Omegon Cronus eyepiece series is a well-thought-out choice for anyone looking to build a functional and affordable eyepiece collection without compromising on image quality.

About Omegon

Omegon is a brand that stands firmly on the side of astronomers - whether they are just starting out or have years of observing experience behind them. Products are developed with a focus on practicality, optical quality and accessible pricing, so that astronomy becomes a pleasure rather than a source of frustration caused by unsuitable equipment. The wide range of accessories, eyepieces and telescopes under the Omegon brand allows you to build a complete setup consistently, with confidence that all the components fit together. The Cronus is a good example of this - a carefully designed optical construction at a price point that will not put you off.

Technical specifications