Omegon 90/500 OTA telescope
Are you looking for a versatile optical tube that can serve as a guide scope for astrophotography, act as a powerful finderscope alongside a larger telescope, and still deliver a satisfying view of the night sky? The Omegon 90/500 OTA is exactly that - a compact, lightweight and surprisingly versatile achromatic refractor with a 90mm objective lens and a focal length of 500mm (f/5.5).
Optical performance
The 90mm achromatic objective delivers a solid light ratio of f/5.5, an angular resolution of 1.15″ (Rayleigh criterion) and a limiting magnitude of 12.2 mag. The light gain over the naked eye reaches a factor of 165, meaning that even at low magnifications you will reveal objects that would otherwise remain invisible. The recommended maximum magnification is 80x, at which the optics perform at their best without unnecessary over-magnification. The fully enclosed tube protects the optics from dust and air currents - a feature you will particularly appreciate during long imaging sessions.
Focuser and accessories
The 2″ Crayford focuser accepts wide-angle eyepieces with a field of view of up to 72°. For example, a 32mm eyepiece gives 15x magnification and a 26mm eyepiece gives 19x - a combination ideal for panoramic sweeps of the Milky Way or large star clusters. The package includes reduction adapters for both 1.25″ and 2″ eyepieces, making the tube compatible with the vast majority of eyepieces on the market.
The tube rings are connected by a short Vixen-standard rail that also features a 1/4″ photographic thread, allowing quick and reliable attachment to a mount or tripod. With an Amici prism (sold separately), the telescope can also be used for terrestrial observation such as nature watching.
Omegon 90/500 OTA as a guide scope
The Omegon 90/500 OTA makes an excellent guide scope - its low weight of 2.2 kg places minimal load on the mount, while the shorter focal length of 500mm provides sufficient magnification for accurate guiding without excessive sensitivity to atmospheric turbulence.
The tube is well suited for astrophotography of planets, the Moon and bright double stars. For nebulae and distant galaxies, however, its aperture is more of a starting point - a larger instrument is recommended for those targets. For solar observation, a certified solar filter must be used; observing the Sun without a filter is strictly prohibited.
Specifications
| Parameter |
Value |
| Objective type |
Achromatic refractor |
| Aperture |
90 mm |
| Focal length |
500 mm |
| Focal ratio |
f/5.5 |
| Angular resolution (Rayleigh) |
1.15″ |
| Limiting magnitude |
12.2 mag |
| Light gain over naked eye |
165x |
| Maximum recommended magnification |
80x |
| Focuser |
Crayford, 2″ output |
| Included adapters |
1.25″ and 2″ |
| Dovetail rail |
Vixen standard |
| Tripod thread |
1/4″ |
| Weight |
2.2 kg |
About Omegon
Omegon is a brand built for astronomers who know what they want. Behind every product stands a team of experienced observers and night-sky photographers who prioritise practicality, optical quality and a sensible price-to-performance ratio. Omegon offers a wide range of accessories - from eyepieces and filters to mounts and guide cameras - so you can easily expand your 90/500 OTA in whichever direction your astronomical passion takes you. If you are looking for a reliable partner for the night sky without compromise, Omegon is a choice you will not regret.
