How to measure the swing diameter

Measuring the swing diameter is very simple, but it is important to ensure that it is measured correctly to avoid selecting the wrong size.

The measurement must be taken from the tip of the mount’s rotation axis if the mount is a traditional German equatorial mount (EQ6R, EQ8, AM3, AM5, etc.), and from the center of the axis if the mount is center-balanced (CEM40, CEM70, CEM120, CQ350, etc.).

The measurement should extend to the farthest point of the entire setup, which may be:

The front end of the telescope tube

The camera

The guide telescope

The counterweight bar

Any protruding equipment such as an ASIAIR, mini-PC, tandem telescope, cables, etc.

Below we provide some reference images for clarity.
Red indicates the correct measurement, while light blue indicates examples of incorrect measurements.

Please note that if you use a flat panel (flats generator) or an automatic dust cover, it must be measured in the open position.

Finally, add 3 inches of tolerance to the measurement to account for possible cable movement or small measurement errors.
The resulting value is your swing radius.
Multiply this value by two and you will obtain the required swing diameter.