Celestron Telescope Driver with Sharpcap

[admin]

Hi,

fortunately this error pretty much tells you the issue in the message - the mount is refusing to GOTO the co-ordinates because it isn't (or thinks it isn't) tracking. This is a reasonable thing for the mount to complain about, because if you are not tracking then once the GOTO completes, the co-ordinates will immediately start to drift.

Now, the first thing to do is to make sure you have the very latest version of SharpCap from the downloads page (4.1.13651) - there was an issue like this a few weeks back and the problem there was that SharpCap was telling the mount to start tracking but not waiting long enough for it to actually get going before sending the GOTO command, so maybe the very latest version will fix the issue.

Alternatively, just make sure you turn on the tracking on the mount first by toggling the tracking button in the mount control area (see https://docs.sharpcap.co.uk/4.1/#GOTO%20Mount%20Control).

cheers,

Robin

[TheAstrophotographer]

Robin,

Would this have any to do with not having conducted an alignment with StarSense hand controller yet?

I ask because I believe I just downloaded the latest version of SharpCap Pro but maybe I am not remembering this correctly. I guess I will confirm the version on my computer.

Thanks,

Edmund

[TheAstrophotographer]

Robin,

I have confirmed that I have the SharpCap Pro dated 8/25/25 on my computer (see attached). Would appreciate your input?

Thanks,

Edmund

[TheAstrophotographer]

Robin,

Or could it be that Celestron ASCOM driver 6.1.7350 does not support MoveAxis functionality and I need to use ST4 controls similar to PHD2? I have my ZWO ASO220mm-mini connected to my NexStar 8SE guide port; therefore, do I need to change the mount setting of SharpCap Pro from Celestron ASCOM driver 6.1.7350 under ASCOM HUB Device to "On Camera ST4" option?

Please note, the main camera ZWO ASI676MC, which I have selected in SharpCap Pro as my camera, is not connected to the mount via "On Camera ST4"; however, my ZWI ASI220mm-mini guide camera is connected via the ST4 port. Therefore, will SharpCap Pro even know to use the guide camera or how will this work?

Or is all this because I have not yet aligned my mount manually using the StarSense hand controller since I will need to do that now that I have moved away from Celestron CPWI ASCOM driver to the Celestron ASCOM driver 6.1.7350?

Thanks,

Edmund

[admin]

Hi,

for the ST4 guiding, I assume that you want to use PHD2 to guide the mount, so you would connect the ST4 cable from the ASI220mm-mini to the mount, then you would use PHD2 to open the ASI220 for guiding, and it will use the camera to detect any drift and send the corrections via the ST4 port (you have to select the mount as 'On Camera' in PHD2 for this to work).

SharpCap doesn't need to know or care about any of the details of this - it will be controlling your 676MC camera for imaging and (optionally) talking to PHD2 to monitor guiding status and request dithering. The lack of MoveAxis in the ASCOM driver isn't critical for deep sky imaging, as that is all usually done with GOTO movements. There are some features that you won't be able to use because of the lack of MoveAxis, like the solar/lunar feature tracking, but there are still plenty of things that will work fine.

cheers,

Robin

[turfpit]

I have done ST4 guiding with PHD2 in the past. It works. As Robin says choose 'On Camera' for the mount.

Dave

[TheAstrophotographer]

@turfpit, appreciate that and I will try ST4 via "On Camera".

Thanks,

Edmund

[TheAstrophotographer]

@turfpit, I wonder if you need to do a calibration step to ensure that the voltages being sent by each pin of the ST4 port of the ZWO ASI220mm-mini to the Auto Guide port of the NexStar 8SE, so that PHD2 knows in which direction the mount moves in the direction intended?

Thanks,

Edmund

[admin]

Hi Edmund,

PHD2 calibration allows PHD2 to work out which way the image moves for each of the four directions that the mount can be moved (via the ST4 port). This deals with which of the four ST4 wires does what, as well as the rotation of the camera in the telescope tube, the magnification and so on.

Actually, the ST4 port is based on a current loop protocol, not voltages, and there is only one movement speed, so there is no need to calibrate voltages or anything like that.

cheers,

Robin

[turfpit]

Edmund

I just plugged the camera ST4 port into the mount and that was it - it worked OK. I moved onto a guide cam and the mount connected to the computer at a later date.

Dave