I currently own this mount from Clearsky and actively use it. I am very satisfied with its performance. I have a relatively large 122/854 mm refractor mounted on it along with a DUO camera, and the mount handles it effortlessly. Under good seeing conditions, I achieve excellent guiding accuracy with an RMS around 0.5 - 0.7. The mount is sold at a very attractive price; the cost of mounts from other manufacturers with similar specifications can be as much as two times higher.
This is a high-precision strain wave gear mount that, despite its compact size, offers a payload capacity of up to 20 kg without the need for counterweights. However, I tested adding a small weight, which did not affect the guidance accuracy.
The mount is richly equipped with technical features for smooth and safe operation, including a physical home sensor, a mechanical limit function adjustable via the panel, and an electromagnetic brake that prevents expensive gear from dropping in the event of a power failure. It also features an azimuth self-locking screw for added reliability.
A huge advantage for astrophotographers is the excellent hub cable management function. There is a 12V DC output and an equatorial instrument data serial port located directly on the dovetail groove, which greatly minimizes the number of cables hanging off the telescope. The base is designed for maximum stability, featuring up to four screws to lock the pitch securely. After performing the polar alignment, a pair of screws is placed on each side to securely lock the Altitude setting in place.
The mount runs on the versatile, open-source OnStep computerized GoTo system. This makes it compatible with a wide range of popular planetarium and control software. The drivers are freely available and updated. The mount can be connected to a PC or other control device using a standard USB-C cable, or wirelessly via Wi-Fi or Bluetooth. A variety of parameters and settings for the mount can be configured through the web interface.
Check out this time-lapse video from one night when I was photographing deep-sky objects with my APO refractor on a Clearsky ST20 mount.
(If the video player throws Config Error 153 due to browser restrictions, you can watch it directly on YouTube here.)
| Mount Name | Clearsky ST20 |
|---|---|
| Gear Type | Harmonic (High-precision strain wave gear) |
| Payload Capacity | Up to 20 kg without counterweights |
| My Guiding Accuracy (RMS) | Around 0.5 - 0.7 (under good seeing) |
| My Current Payload | 122/854 mm refractor + DUO camera |
| Safety Features | Physical home sensor, panel mechanical limit, electromagnetic braking |
| Integrated Connectivity | Hub cable management, 12V DC output on groove, serial data port |
| Other Features | Azimuth self-locking screw, highly stable base, magnetic wrench |