Sky-Watcher MC 90/1250 SkyMax OTA Telescope
The Sky-Watcher MC 90/1250 SkyMax is a compact and exceptionally capable Maksutov-Cassegrain optical tube assembly designed for observers who want serious planetary and lunar performance in a package small enough to fit in a backpack. With a 90 mm aperture folded into a tube just 24 cm long and weighing only 1.3 kg, this is one of the most portable high-focal-length telescopes available - and one of the best-regarded in its class. BBC Sky at Night Magazine described the optics as "staggeringly good, giving superb views of the Moon" and noted it "also excels for double-star observations."
This model is sold as an OTA (optical tube assembly only) - no mount is included. It is aimed at observers who already own a suitable mount and want to add a highly portable high-magnification instrument to their setup, or who are building a customised travel rig around a mount of their choice.
Maksutov-Cassegrain Design - Long Focal Length in a Short Tube
The Maksutov-Cassegrain optical system achieves a focal length of 1250 mm at f/13.9 within a tube that is a fraction of the size a refractor of equivalent focal length would require. The design uses a large spherical primary mirror and a secondary mirror integrated into the rear surface of a thick corrector lens at the front of the tube. This arrangement produces sharp, high-contrast images free of chromatic aberration - the colour fringing that affects simpler achromatic refractors. The result is clean, well-defined detail on the Moon and planets with a deep black sky background that longer focal ratios naturally provide.
The central obstruction of the secondary mirror is relatively small at around 32% of the aperture, which helps preserve image contrast - an important factor for planetary work where subtle surface detail is the main target.
What You Can Observe
The combination of 90 mm aperture and 1250 mm focal length makes this telescope particularly well suited for the Moon and the planets of the Solar System. The lunar surface reveals itself in extraordinary detail - thousands of craters, mountain ranges, valleys, and the subtle texture of the mare plains. On Jupiter you will see the main equatorial cloud bands and the four Galilean moons as tiny distinct points. Saturn's rings are visible even at lower magnification, and at higher power the Cassini Division within the rings can often be resolved under good seeing conditions. Venus shows its phases clearly, and Mars reveals polar ice caps and surface markings during opposition.
Beyond the Solar System, the long focal ratio makes the SkyMax 90 an outstanding instrument for splitting close double stars - a rewarding and often underestimated area of visual astronomy that requires exactly the kind of high-contrast, high-magnification performance this telescope delivers.
The sealed tube design also makes the SkyMax 90 an excellent daytime spotting scope. The long focal length and aperture produce bright and detailed terrestrial views, and the corrected optics give a clean image without the colour fringing that can affect cheaper alternatives.
Astrophotography
The focuser is equipped with a T-thread, allowing direct connection of a DSLR or mirrorless camera body using a standard T2 adapter (not included). This turns the SkyMax 90 into a powerful 1250 mm telephoto lens capable of capturing detailed lunar images and bright planet shots. The compact size and low weight make it easy to balance on a motorised mount without requiring heavy counterweights.
Included Accessories
- 25 mm eyepiece - 50x magnification (1.25")
- 10 mm eyepiece - 125x magnification (1.25")
- 90° star diagonal, 1.25"
- Red dot finder
- Vixen-style dovetail plate for mounting compatibility
- Carry bag
Key Specifications
- Optical design: Maksutov-Cassegrain
- Aperture: 90 mm
- Focal length: 1250 mm (f/13.9)
- Maximum magnification: 180x
- Magnifications with supplied eyepieces: 50x and 125x
- Eyepiece barrel diameter: 1.25" (31.7 mm)
- Focuser: Rack-and-pinion with T-thread for camera attachment
- Dovetail plate: Vixen-style
- Tube length: approx. 240 mm
- Weight: 1.3 kg
- Mount: not included
Whether you are looking for a compact grab-and-go instrument to complement a larger telescope at home, a travel scope that will keep up with your expectations in the field, or a dedicated planetary OTA to pair with a GoTo mount - the Sky-Watcher MC 90/1250 SkyMax delivers optical quality and versatility that is hard to match at its size and price point.
