What is the ST4 port for on this motor?

[Crignog]

I have just received my SkyWatcher StarQuest 130p, and I've had it in my head that I will get the RA Motor Drive to go along with it. The device has an ST4 port "for auto-guiding". I don't really understand what that means. Do I plug a cable from a computer into the motor to track stars more accurately?

[Cornelius Varley]

8 minutes ago, Crignog said:

I have just received my SkyWatcher StarQuest 130p, and I've had it in my head that I will get the RA Motor Drive to go along with it. The device has an ST4 port "for auto-guiding". I don't really understand what that means. Do I plug a cable from a computer into the motor to track stars more accurately?

The ST4 port allows the mount to be controlled by autoguiding software such as PHD (Push Here Dummy) during imaging. Usually a small telescope, known as a guide scope, together with a camera are attached to the main scope. The images taken by the guide camera are monitored by PHD and the software sends commands back to the mount using the ST4 port to correct for any drifting during imaging. 

[Crignog]

Just now, Cornelius Varley said:

The ST4 port allows the mount to be controlled by autoguiding software such as PHD (Push Here Dummy) during imaging. Usually a small telescope, known as a guide scope, together with a camera are attached to the main scope. The images taken by the guide camera are monitored by PHD and the software sends commands back to the mount using the ST4 port to correct for any drifting during imaging. 

Thanks for your reply! Is it a specific type of camera I would need to use?

[Cornelius Varley]

Just now, Crignog said:

Thanks for your reply! Is it a specific type of camera I would need to use?

The port is for guiding during imaging only and not used for visual work.  Most astroimaging cameras have an ST4 port .