Error message sometimes disconnects when changing exposure

[Tony Vale]

I am trying to get a new camera and telescope working with Sharpcap and I find, not always but fairly often that when I change exposure time, I get an error message. I have attached a screenshot of the message and also of the details of the QSI 726 camera. I have set the Capture area to the Resolution details in the camera spec. The message suggests the problem could be something to do with ROI. I will always want to use the whole sensor so do not wish/need to set an ROI. A log is also attached.

Version of SharpCap: SharpCap Pro (V4.1.14304, 64 bit)
Operating system : Windows 11 Pro Version 25H2
Focuser: Pegasus FocusCube3
Mount: EQ6 Pro
Camera (with integral filter wheel): QSI 726

I hope you can help !

Kind Regards,
Tony Vale

[admin]

Hi Tony,

I think the problem is occurring because SharpCap tries to stop the current exposure in progress when you change the exposure time - the log reveals that the camera is not returning to the Idle state after being told to stop, which SharpCap notes but ignores (plenty of cameras fail to update the state properly at this point, so SharpCap is set up to wait a certain amount of time for the camera to go idle, then try to continue anyway).

I suspect from the way the log continues that after this the camera driver ends up in an inconsistent state, where it claims it has an image ready, but gives an error when SharpCap asks for the image data. SharpCap treats this as an error (after a couple of retries) and that's the end of things...

The most immediate thing you can try is to flip SharpCap into 'still camera' mode by toggling the 'Live View' button at the left of the toolbar off. In this mode, SharpCap only captures images on request, rather than continuously. A change of exposure in this mode will not stop the current exposure, but will only be used when the *next* image is requested. You will note when capturing images in this mode that there is a 'cancel' button to cancel an exposure - use that with caution - it might trigger the same bug as you are seeing when changing exposure.

Hope this helps,

Robin

[Tony Vale]

Hi Robin,
Thanks for your reply - yes that is helpful.
When I switch out of Live Mode to Still mode, should I wait for the current exposure to end or will SharpCap try to cancel it ? If so, might that trigger the same problem ?
It sounds as though I will need to use Live Mode more carefully than I was used to when I used it with a ZWO camera. Would that be your advice ?

Kind Regards,
Tony

[admin]

Hi Tony,

you can always switch into still mode *before* opening the QSI camera to avoid any problems in the switchover. For ASCOM cameras, SharpCap only tries to cancel the existing exposure if the current exposure value is 2.5s or above - if the exposure is shorter than that then there is typically no point in trying to cancel as the exposure will be over soon anyway.

Out of interest, does the problem go away if you select a small ROI like 320x200? It's possible that it is all happening because SharpCap is not waiting long enough for the readout to happen on the older CCD camera after stopping the exposure...

cheers,

Robin

[Tony Vale]

Hi Robin,
Sorry, I have only just read your last response. I haven't tried changing the ROI but by using Framing Shot when I am changing exposures rather than LiveView I haven't found it to be too much of a problem. I also use the sequencer a lot for live observations which cuts down the chance of me forgetting I am in live view.
Incidentally, the QSI 726 is actually a CMOS camera with a Sony IMX571 sensor which brings me to another question. I am only able to select high, medium or low gain through SharpCap but not Custom, which would allow me to set gain values from 0 to 420. This is not a problem for me as low or medium is all I am likely to need as a photometrist. However, the photometry software needs to be told what the e-/ADU values and read noise are for an observation so I ran sensor analysis and got the following :-


Sensor Analysis from SharpCap
1
Gain Value e/ADU Read Noise (e) Full Well (e) Relative Gain Rel. Gain (db) Dynamic Range (Stops)
1 0.768301293 3.587734382 50351.39355 1 0 13.776671
2 0.301032779 1.635689129 19728.4842 2.552218054 8.138355531 13.55809391
3 0.021108817 1.412108309 1383.38742 36.39717466 31.22135346 9.936138779


There are only 3 gain values. Am I safe to assume that sensor analysis is restricted to the same gain settings that are available through the Gain dropdown and therefore that Gain 1 is low, 2 is medium and 3 is high ? If so, I think I have all I need.

Kind Regards,
Tony

[Tony Vale]

Apologies, the spacing for the sensor analysis report makes it hard to read. Hopefully the attachment is better.

Regards,
Tony

[admin]

Hi Tony,

yes, the 3 gain values you get in the report will correspond to the three available in the dropdown - those are unfortunately all the options that SharpCap can control (the ASCOM driver specifies what the gain options are, then SharpCap just displays them). With a lot of ASCOM cameras, you can get at more functionality in the 'Setup' window for the ASCOM driver, but because of the limitations of ASCOM, SharpCap can't get at those settings directly - they have to be changed by the user via the setup window.

It looks like your values for e/ADU for low/med/high are 0.76, 0.30 and 0.021, while the read noise values are 3.59, 1.64 and 1.41.

cheers,

Robin