Refractor Telescope Skywatcher BK 120/600 OTA — 120mm Aperture, 600mm Focal Length

Skywatcher BK 120/600 OTA is a 120 mm aperture refractor optical tube assembly with a 600 mm focal length. The achromatic refractor design delivers a bright, wide field of view suitable for visual observation of the Moon, planets and brighter deep-sky objects. Supplied as an OTA, this instrument is intended for mounting on compatible photographic or equatorial mounts and is optimized for straightforward setup, portability and daytime as well as night sky viewing.

Advantages

The 120 mm aperture gathers a significant amount of light for detailed views of lunar and planetary features and improved performance on bright nebulae and star clusters. The relatively short 600 mm focal length produces a wide, low-power field that is easy to navigate and well suited to visual observation as well as low-magnification astrophotography. The OTA format keeps the optical tube compact and transportable while allowing users to select a mount and accessories according to their needs.

Suitable for

• Visual observation of the Moon and planets
• Wide-field views of bright nebulae and open star clusters
• Beginner and amateur astronomers seeking a portable refractor OTA
• Use on photographic or equatorial mounts for visual or basic imaging

Key specifications

• Aperture: 120 mm
• Focal length: 600 mm
• Optical design: achromatic refractor
• Focal ratio: f/5
• Mounting: OTA (requires compatible mount)
• Primary use: visual observation, wide-field imaging potential

How to use

Attach the optical tube assembly to a suitable mount using the provided mounting plate or dovetail, ensuring the mount capacity matches the OTA weight. Balance the assembly and align the mount according to its type (azimuthal, alt-az or equatorial). Fit an appropriate eyepiece in the focuser to achieve the desired magnification; start with a low-power eyepiece to locate targets and then switch to higher powers for planetary detail. For basic astrophotography, use a stable equatorial mount with tracking and a camera adapter matched to the focuser.

Usage recommendations

For best visual results, use low- to medium-power eyepieces to exploit the wide field offered by the 600 mm focal length. Cool the telescope outdoors before observing to reduce thermal currents inside the tube. When imaging, prefer short exposures on bright targets or guide accurately on longer exposures; select a mount with tracking capability when planning astrophotography.