SharpCap PHD2 compatibility problem(?)

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Joined: Fri Feb 07, 2020 9:26 am

SharpCap PHD2 compatibility problem(?)

Post by Neil-f » Wed Feb 12, 2020 2:29 pm

For some years I have been successfully using PHD2 with a Starlight Xpress Lodestar2 for autoguiding and taking images with a Canon 70D. I am now looking to switch over the Canon to a dedicated astrophotography camera, where I will use Sharpcap Pro as the imaging software. In preparation for this and to make sure that everything was going to work, I set up a Starlight Xpress Colour Superstar camera as the image taker on Sharpcap Pro - I declared in the Sharpcap Guiding menu that I was using PHD2 for autoguiding. I also clicked on ‘Enable Server’ in the PHD2 setup as per the Sharpcap manual. I then attempted to autoguide using the Lodestar and PHD2 and immediately got an Ascom error (see screen shot attached) which stated:-
"Exception thrown polling camera
(ASCOM SXCamera) Unable to complete get_ImageReady request due to previous error"
Sharpcap Pro also froze at this point such that I had to re-boot. Can anyone suggest what has gone wrong here? I subsequently ran Ascom Diagnostics and found no reported errors. I might add that although I normally run 64 bit apps, Sharpcap Pro is running at 32 bits to accommodate the Starlight Xpress cameras.
Sharpcap Pro v. 3.2.6219.0 32-bit
Starlight Xpress Colour Superstar camera for imaging
Starlight Xpress Lodestar 2 camera & PHD2 v.2.6.7 for autoguiding
Win 10 Pro v. 1909 OS build 18363.628
(178.12 KiB) Downloaded 23 times

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Re: SharpCap PHD2 compatibility problem(?)

Post by admin » Wed Feb 12, 2020 10:44 pm


An interesting problem – I only have one StarlightXpress camera here to test with, so there's no way that I can reproduce the problem. It sounds as though accessing the superstar camera in SharpCap has somehow locked out PHD2 from accessing the lodestar camera if I understand you correctly.

As an experiment, you could try using one of the 'test' cameras in SharpCap that are at the bottom of the camera list – these just show a fixed image on the screen and give you some controls to make adjustments with. I suspect that if you use one of these cameras then you will not see the problem in all PHD2 - if that's the case then it would confirm that it's the use of the superstar camera inside SharpCap that is causing the problem rather than anything else in SharpCap.

I wonder if anyone else here on the forums has used two or more StarlightXpress cameras successfully?

Cheers, Robin

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Re: SharpCap PHD2 compatibility problem(?)

Post by BlackWikkett » Thu Feb 13, 2020 3:20 am

I've seen this behavior before when using a ZWO camera for imaging and a ZWO camera for guiding. Sometimes PHD2 will select the imaging camera for guiding then you connect SharpCap or other imaging software and two applications are fighting for control of the same camera and the circus clowns are not happy. This may or may not be the case for Loadstar but have a look at the "connect equipment" dialog in PHD and click the double arrow button and make sure that PHD is using the correct camera for guiding. See image below.

ImagePHD2 Camera Chooser by Black Wikkett, on Flickr


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Re: SharpCap PHD2 compatibility problem(?)

Post by Neil-f » Tue Feb 18, 2020 1:58 pm

I think BlackWikkett hit the nail on the head. I was unable to access the field highlighted since it was greyed out but I did substitute an old Altair GPCAM for the Lodestar 2 and did not encounter the earlier problem. PHD2 didn’t error at the point of initiating autoguiding calibration and Sharpcap did not freeze.
Thanks to admin and BlackWikkett for your help

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