Sky-Watcher Tube Rings 90 mm

90 mm tube-ring set

This 90 mm cast-aluminium tube-ring set is the manufacturer-listed size for BK909. Ring size refers to the tube mounting requirement, rather than the telescope’s objective aperture.

Opening and adjustment

The hinged rings open for installing or removing the tube. Loosening their locking screws allows the tube to rotate or slide for balance; tighten them securely before use.

Camera attachment

One ring has a standard 1/4-20 piggyback camera thread. Match the ring size to the optical tube and use a suitable mounting plate; the manufacturer does not publish a universal bolt pattern or instrument load rating.

Sky-Watcher manufacturer documentation