Refractor optical tube Skywatcher BKED 100 OTAW — 100 mm aperture, 900 mm focal length

Skywatcher BKED 100 OTAW — 100 mm aperture, 900 mm focal length is a refractor optical tube designed for both visual observation and astrophotography. The BKED (Black Diamond ED) optical configuration uses extra-low dispersion glass to reduce chromatic aberration and improve contrast across the field. With a 100 mm objective and a 900 mm focal length, this optical tube delivers a moderate focal ratio suitable for planetary, lunar and many deep-sky targets while remaining compact and portable for field use.

Advantages

The BKED 100 features ED optics that limit colour fringing and increase image sharpness, providing clearer views of planets and brighter deep-sky objects. Its 900 mm focal length offers a balance between magnification and field of view, making it versatile for a range of targets. The optical tube is compatible with standard mounting interfaces and is light enough to be used on a variety of equatorial and alt-azimuth mounts, facilitating transport and setup.

Suitable for

• Visual observation of the Moon and planets
• Wide-field and medium focal length astrophotography of nebulae and star clusters
• Portable observing sessions and travel astronomy
• Use on compatible equatorial and alt-azimuth mounts

Key specifications

• Optical design: Refractor with ED (extra-low dispersion) glass
• Aperture: 100 mm
• Focal length: 900 mm
• Focal ratio: f/9
• Suitable applications: Visual observing and astrophotography
• Physical characteristics: Compact optical tube designed for portability

How to use

Mount the BKED 100 optical tube on a stable equatorial or alt-azimuth mount rated for its weight and length. Collimate and level the mount, then attach the finder scope and balance the tube before adding eyepieces or a camera. For visual observing, start with a low-power eyepiece to locate targets and then increase magnification as seeing conditions permit. For astrophotography, use a dedicated camera and appropriate adapters; perform focus and guiding routines and calibrate exposure and tracking according to the chosen target.

Usage recommendations

Use the optical tube on a mount with sufficient payload capacity and good tracking performance for long-exposure imaging. Allow the scope to reach ambient temperature before high-magnification observing or imaging to reduce thermal currents. Regularly check and clean optical surfaces only with appropriate tools to preserve ED coatings and optical quality.