ST-4 autoguider

[Mikaellm1234]

I am going to buy the HEQ5 SynTrek mount. It says that it has ST-4 autoguider port. What is it?

Link: http://www.firstlightoptics.com/skywatcher-mounts/skywatcher-heq5-syntrek.html

Clear skies!

Mikael

[RikM]

It is a port to connect an autoguider directly to the mount.

For long exposure astrophotography, the mount motors / gears don't move accurately enough. It is normal to use a second smaller telescope and camera (as well as the main scope/imaging camera) that images a star near your target object. Software can track the position of this guide star as the mount moves and feed correcting signals to the mount motors, via the ST4 port, to guide the mount more accurately.

[Cornelius Varley]

The ST4 autoguider port is a socket on the mount which allows you to connect the mount, through a suitable interface (autoguider or a guide camera with a ST4 port), to your laptop. When taking long exposure DSO images the telescope may start to drift off the target, a second camera (guide camera / scope) takes images which are monitored by some special software which can send corrective commands back to the mount through the ST4 port to keep the imaging target on the sensor. There are also all-in-one guiders which connect directly to the ST4 port and dispense with the need of a separate connection back to the laptop http://www.firstlightoptics.com/guide-cameras/skywatcher-synguider-autoguider.html .