Sky-Watcher 150/1800 Black Diamond OTA Telescope
The Sky-Watcher 150/1800 Black Diamond is a serious Maksutov-Cassegrain optical tube assembly that combines a generous 150 mm aperture with a 1800 mm focal length in a surprisingly compact and portable package. Built with Schott glass optics and finished in the distinctive metallic black diamond coating that gives the series its name, this telescope sits at the high end of Sky-Watcher's Maksutov-Cassegrain lineup - and is widely regarded as one of the best dedicated planetary telescopes available at its price point.
This model is sold as an OTA only - no mount is included. It is designed for observers and astrophotographers who already own a suitable equatorial or HEQ-series mount and want to add a high-performance, long focal length instrument to their setup.
Optics - Schott Glass and Exceptional Contrast
The optical elements of the Black Diamond are manufactured from Schott AG glass - one of the most respected names in precision optical glass, also associated with Carl Zeiss. The corrector lens carries a metallic high-transmission coating with over 99.5% transmission, while the primary mirror features enhanced reflectivity coatings achieving over 94% reflectivity. Together these coatings maximise the amount of light reaching the eyepiece, producing bright, sharp, and high-contrast images.
The Maksutov-Cassegrain design uses a thick meniscus corrector lens at the front of the tube and a small aluminised secondary mirror formed as a spot on the rear surface of that corrector. This arrangement virtually eliminates chromatic aberration and produces diffraction-limited optical performance - the gold standard in amateur astronomy optics. The central obstruction is just 31% by diameter, which is notably smaller than in Schmidt-Cassegrain designs and contributes to the exceptional image contrast this telescope is known for.
A Dedicated Planetary Telescope
With 1800 mm of focal length at f/12, the Sky-Watcher 150/1800 Black Diamond is optimised for exactly the type of observation where a long focal ratio truly excels: the Moon, the planets, and close double stars. The long focal ratio naturally produces a deep, inky black sky background that makes planetary detail stand out with striking clarity.
The Moon reveals features just a few kilometres wide - tens of thousands of tiny craterlets, mountain ranges, valley systems, faults, and the central peaks of large impact craters. On Jupiter the main equatorial cloud belts are clearly visible, along with the four Galilean moons, and under good seeing conditions the Great Red Spot and finer banding structure can be resolved. Saturn's rings and the Cassini Division within them are beautifully rendered, and Titan and other moons are visible alongside the planet. Mars near opposition reveals polar ice caps and the larger surface markings, while Venus shows its full range of phases.
For double star observers, the 150 mm aperture combined with the long focal ratio and excellent contrast makes this an outstanding instrument. Close pairs that challenge smaller telescopes can be cleanly split, and the colour contrast of mixed-colour doubles appears vivid and well-defined.
Deep-Sky Capability
While primarily a planetary and lunar telescope, the 150 mm aperture of the Black Diamond brings a wide range of deep-sky objects into reach. Globular clusters such as M13 and M22 resolve into individual stars across the core, while galaxies under dark skies begin to reveal structural detail - dust lanes and spiral arm hints are visible in targets such as M51 or M64. Planetary nebulae begin to show colour and fine structure. The narrow field of view that comes with such a long focal length means that large diffuse objects and wide open clusters are less suited to this telescope, but compact and high-surface-brightness objects perform excellently.
Collimation and Maintenance
The rear cell of the tube features collimation adjustment screws, allowing the optical alignment to be fine-tuned if required. In practice, Maksutov-Cassegrain telescopes hold collimation very well due to the sealed tube design, and significant adjustment is rarely needed. The sealed tube also means the optics are protected from dust and moisture and require minimal maintenance.
Astrophotography
The 2" focuser output accepts standard 2" accessories and is threaded for SCT-standard camera adapters, making it straightforward to attach a DSLR or mirrorless camera, or a dedicated astronomy camera, for high-resolution lunar and planetary imaging. The internal mirror-shift mechanism for focusing is smooth and introduces minimal image movement - an important characteristic for imaging work.
Included Accessories
- 28 mm 2" LET eyepiece - 64x magnification (55° field of view)
- 8x50 straight-through finder scope with crosshair
- 2" star diagonal
- Vixen-style EQ dovetail plate for mount compatibility
Key Specifications
- Optical design: Maksutov-Cassegrain
- Aperture: 150 mm
- Primary mirror diameter: 162 mm (oversize)
- Focal length: 1800 mm (f/12)
- Maximum useful magnification: 355x
- Magnification with included eyepiece: 64x
- Eyepiece barrel diameter: 2" (51 mm)
- Central obstruction: 31.3% by diameter
- Corrector glass: Schott AG
- Mirror coating reflectivity: 94%
- Corrector coating transmission: 99.5%
- Dovetail: Vixen-style, EQ/HEQ mount compatible
- Rear cell collimation screws: yes
- Weight: 5.3 kg
- Mount: not included
The Sky-Watcher 150/1800 Black Diamond OTA represents the point where compactness, high optical quality, and true planetary performance meet in a single instrument. If detailed views of the Solar System are your priority and you are looking for an OTA that will reward a good mount with views to match, this telescope is among the strongest choices available in its aperture class.
