Refractor telescope Skywatcher BK 150/1200 OTA — 150 mm aperture, 1200 mm focal length

Skywatcher BK 150/1200 OTA is a refractor optical tube assembly with a 150 mm objective aperture and 1200 mm focal length. The OTA is built for visual observation of planets, lunar detail and brighter deep-sky objects, and can be used for astrophotography when paired with a stable mount and appropriate adapters. As a refractor design, it delivers contrasted images with straightforward collimation and low maintenance compared with more complex optical systems.

Advantages

The 150 mm aperture increases light-gathering capacity and resolution versus smaller refractors, allowing improved detection of faint structure in nebulae and star clusters as well as finer planetary detail. The 1200 mm focal length provides a practical balance between magnification and field of view for both high-resolution planetary work and medium-field deep-sky targets. The OTA format enables flexible use on a variety of equatorial or alt-azimuth mounts and simplifies upgrades for imaging by changing cameras, diagonals or focal reducers.

Suitable for

• Visual planetary and lunar observing at medium to high magnifications
• Observation of bright deep-sky objects such as open clusters, nebulae and some galaxies
• Astrophotography with a stable equatorial mount and imaging accessories
• Use as an optical tube for educational demonstrations and amateur astronomy projects

Key specifications

• Optical design: refractor (achromatic/near-achromatic design typical for BK series)
• Aperture: 150 mm effective diameter for increased resolving power
• Focal length: 1200 mm focal length for a focal ratio of f/8
• Focal ratio: f/8, offering balance between magnification and field illumination
• Mounting interface: compatible with standard dovetail bars for attachment to equatorial or alt-azimuth mounts
• Intended use: visual observation and imaging with appropriate adapters and stable mount

How to use

Attach the OTA to a compatible mount using the dovetail or mounting rings supplied by the chosen mount manufacturer, then balance the assembly before slewing. Begin with a low-power eyepiece to locate objects and center them in the field, then increase magnification as seeing conditions allow. For astrophotography, use an equatorial mount with accurate tracking, connect the camera or planetary imager through the correct T‑ring or extension, and perform focusing and framing using live view or capture software. Check collimation and perform fine focus adjustments regularly for best image sharpness.

Usage recommendations

For visual work, start with wide-field eyepieces and a 2" diagonal to take full advantage of the f/8 focal ratio. For imaging, pair the OTA with a stable equatorial mount and use a field flattener or reducer if wide-field performance is required. Allow the tube to reach thermal equilibrium outdoors for 20–40 minutes to minimise image distortion from tube currents.