Omegon 2″ extension tube, 35mm optical path
Anyone who takes astronomy or astrophotography seriously will sooner or later encounter a frustrating problem: the telescope simply refuses to focus. Not because there is anything wrong with it, but because its focal plane lies further than the focuser can reach. The Omegon extension tube with a 35mm optical path was designed precisely for situations like this - a simple, reliable and precisely manufactured accessory that solves the problem once and for all.
Why do you need an extension tube?
Refractors and many other telescope types are designed with the assumption that the user will employ a star diagonal, erecting prism or other intermediate elements. The focal plane is therefore intentionally shifted further from the body of the instrument. If you decide to attach accessories directly - without a diagonal - or if you are working with a non-standard configuration, you will find that you pull the focuser out to its full extent and still cannot achieve a sharp image. The extension tube bridges exactly this gap between the focuser and the focal plane, without interfering with the optical path or degrading image quality in any way.
Construction and materials
The tube is made of aluminium and finished with black anodising, which provides scratch resistance and a clean aesthetic appearance that matches most modern telescopes. The eyepiece or attached accessory is secured by a brass compression ring - unlike a standard thumbscrew, it will not scratch the eyepiece barrel and at the same time ensures a firm, secure grip without any risk of shifting off the optical axis.
The 2″ barrel features a safety undercut that prevents the tube from accidentally slipping out of the focuser - something you will particularly appreciate when working at night or when handling heavier accessories. With a weight of just 100 g, the tube adds no meaningful load to the assembly and has no effect on the telescope's balance.
Technical specifications
| Parameter |
Value |
| Barrel diameter |
2″ (50.8 mm) |
| Optical path length |
35 mm |
| Material |
Aluminium |
| Surface finish |
Black anodising |
| Locking mechanism |
Brass compression ring |
| Safety undercut |
Yes |
| Weight |
100 g |
Where will you use it?
The extension tube is useful in a wide range of situations:
- Direct visual observation without a diagonal
- Astrophotography with a DSLR or mirrorless camera connected directly to the focuser
- Building longer optical chains with focal reducers, field correctors and other intermediate elements
Thanks to the standard 2″ connection on both ends, it is fully compatible with the vast majority of modern telescopes and accessories. If you need to bridge a greater distance, you can combine multiple tubes or choose a different length from the available range.
About the Omegon brand
Omegon is a brand with a long tradition in astronomical optics and accessories, popular among beginners and experienced observers alike. Omegon products are designed with an emphasis on practicality, precise workmanship and affordability. Every detail - from the choice of materials and surface finishes to design solutions such as the safety undercut and brass compression ring - reflects the fact that the people behind the development truly understand astronomy and practise it themselves. The wide range of compatible Omegon accessories allows you to build a functional and reliable observing setup tailored exactly to your needs.
