Live stack new exposure time issue

[Oberon510]

I have an issue with SC 4.1.13951 when changing my Live stacking exposure time. The first exposure always is the length of the previous session and every other exposure after that is the length that I changed to.

Steps
1) Stop current session with Clear/Live Stack buttons.
2) Select new exposure from my Capture Profiles (e.g go from 300s to 600s exposures)
3) Start Live Stacking and first exposure is the previous session length and the following exposures are the current profile length.

I do not have Live View enabled or anything else that would be setting off exposures. I do have a filter enabled.

Any thoughts?

Thanks,
Ken

[admin]

Hi Ken,

is there an exposure in progress when you start live stacking? (you can tell from the exposure progress bar at the bottom right as long as it is more than 1s exposure). If there is one in progress then that would finish at some point and get added to the stack if it is active at that point...

Anyway, thanks for recording the steps to repro the issue - I will give them a try. If you get a moment, can you post what camera you are using as that could just be important here.

cheers,

Robin

[Oberon510]

Thanks Robin - it is an ASI6200MC. I can't recall if there was an exposure in progress when I pressed the Live Stack button. There would have only been a few seconds after I Clear/Live Stack stopped the previous stack before selecting new exposure profile and starting again. Generally I wait until an exposure is finished before stopping the stack, changing profile and starting again so the previous stack exposure would be close to the exposure start and it may just be that. Note these are 7-10 minute exposures with an OIII filter (IC1396).

I also recall that the same thing happened after I did a FWHM Focus Assistant (FA) run with an OIII filter where exposures were 10-15 seconds. After that completed and I closed the FA there was an FA exposure in progress alert Maybe that is because Live View was enabled at that time.

Ken

[Oberon510]

I ran it again tonight and yes the exposure that was running when I pressed Clear/Live Stack still runs causing the issue. Is there a way to stop an exposure after Clear/Live Stack buttons are pressed - the stop recording button is not available at that stage?

Thanks,
Ken

[admin]

Hi Ken,

I *thought* that the load of a profile should cancel the existing exposure (as it changes the length of the exposure control). Maybe that doesn't happen when in still mode - I will have to check that on a ZWO camera and see what happens - I'll come back to you.

On the workaround side, while you are capturing in still mode there is usually a notification bar at the top telling you that a capture is in progress - this has a cancel button on it, so you could try using that.

cheers,

Robin

[Oberon510]

OK - will use that.

I tried again last night and it ran correctly. I will do some more work to get a repeatable flow for you but don't want to cloud the situation until then.

Thanks,
Ken

[Oberon510]

Well my testing has a few hits and misses.
I started a new profile with 240s exposures, stopped it after one exposure (Clear/Live Stack) and then changed the profile to 60s exposures and I noticed that the frame was still running but no option to stop it. Other times it would stop cleanly (no frame still capturing). When I started Live Stack for the 60s profile the first frame went to 240s.

I tested 30s exposures for LRGB without changing the profile during those stacks and some would not stop the frame capture cleanly after Clear/Live Stack was pressed so I had to wait for the capture to stop before starting the next stack with the new filter - see photos attached.The odd thing is that some did stop cleanly.

Ken

[admin]

Hi,

OK, I had a look into this too and worked out that the way that still mode works is deliberately different from live mode... If you change the exposure length in live mode then it tries very hard to stop the existing exposure as soon as possible and start a new exposure of the new length. On the other hand, in still mode once an exposure is started it keeps running that exposure even if the exposure value in the controls is changed.

So, with no automatic stop to the current exposure on change of the exposure length when in still mode, it's not guaranteed (in the current code) that a profile load will reset the exposure. That will only happen if the profile load changes something (bit depth, resolution, binning, etc) that forces the camera to re-initialize.

So, I will have to think about whether cancelling the existing exposure on profile load in still mode is a good thing. One thing that will probably help is that the 'Stop Capture' button can be used at any point during a still mode exposure to cancel the current exposure (even if the notification with the cancel button has vanished).

cheers,

Robin

[Oberon510]

One thing that will probably help is that the 'Stop Capture' button can be used at any point during a still mode exposure to cancel the current exposure (even if the notification with the cancel button has vanished).

Thanks Robin - just to be clear the Stop Capture button is not active at that stage. See attached. I will make sure I wait for it to finish before initiating a new Live Stack.

My other thought is what happens to that capture if I do initiate a new Live Stack while it is running - does it use it as the first image for the stack or discard it. If it uses it then it may not have the changes that were made (eg filter change).

Thanks for looking into it and I will defer to your findings.

As we are in the last stretch to the holidays, merry Ho Hos to you and the SharpCap team - appreciate all the good work.

Regards,
Ken

[admin]

Hmm, interesting...

the screenshot you have shared shows SharpCap in an odd, inconsistent state -

* In one way it thinks that it is not capturing a frame - the 'stop capture' button is not enabled, but the 'Start Capture' , 'Framing Shot', etc buttons are. Also the notification is showing that a frame has been cancelled.

* In another way it does think it is in progress - the progress bar still shows progress at the bottom right.

I think that this is causing the issue, but what allows that inconsistent state to happen isn't clear... I haven't managed to get the application into that state in my testing.

Can you repeat the test and then send me a SharpCap log captured after you have seen this problem happen? The log will hopefully help me track what happened at what times, if anything went wrong in unexpected ways, etc, and then work out how to fix the issue. I think that's probably the best way forward. If you could also post a fairly detailed step-by-step of what you do to make this happen then that would be great as I could line up those steps with what I see in the log to really get a picture of what was going on and why.

Thanks for the xmas wishes - hope that you and yours also have a very festive time!

Robin