Images taking twice as long to capture in live stack and dark capture

[nigeld]

Hi
New user here. I tried using live stacking for the first time and used the 4.1 version. I noticed that quite often the images after the first one would take longer than the 15secs exposure time. I thought this might be down to the stacking and the applying of darks and flats but the status panel was showing that those were totaling less than 2 secs while the delay was much longer.

Yesterday I was using 4.1.11031 to capture darks and noticed it was doing the same - first frame ok, later frames taking twice as long. This was repeatable. I tried various things as I was thinking there was a usb error or something wrong with my external usb drive (I have had corruption errors on it and formatting was taking a long time) but the problem seemed consistent. I then tried the latest 4.0 version and the darks took the correct amount of time.

This is using an sv705c svbony camera with a mini pc running windows 11


PS I also noticed that it says it’s going to take 1 more image than I’ve asked for. EG if I want a stack of 10 darks it says 11 in the status bar at the bottom. Similar for live capture when auto save was on I believe.

[admin]

Hi,

are you seeing the number of dropped frames in the bottom left hand corner go up when frames are taking twice as long as usual to capture? That would kind of partly make sense, since the only significant difference between the SVBony camera code in 4.0.9562 and 4.1 is that 4.1 will give up on a frame if it ends up waiting 20s beyond the expected exposure time. On the other hand, this code should only activate if there is a problem anyway, which is concerning...

I don't have a 705 here to test with, but do have a 605CC which seems to work fine for 15s exposures in RAW16 mode in 4.1

When you went back to 4.0, was it 4.0.9562? If it was an older version then there may be additional changes in the SVBony camera handling between your version of 4.0 and 4.1 that might help explain what is going on.

cheers,

Robin

[nigeld]

No sign of any dropped frames.

I’ve got an sv305 so will give that ago.

Is there any additional logging you want me to turn on?

I’ve only just started using sharpcap so the 4.0 version was 4.0.9562.0 64bit

[nigeld]

Ok the sv305 works fine.

With the sv705c it takes the first frame fine then takes twice as long for the following ones. The banner at the top saying ’exposing for..’ stays until around 7 secs after the 15sec exposure should have finished. Then it goes away before the banner saying something like ‘Writing to…’ appears very briefly at the end of the extra 15 secs.

I tried live view and could manage 12fps with no sign of any dropped frames. It did the same fps on 4.0. Astrodmx seems to perform similarly.

BTW both 4.0 and 4.1 take 11 frames (or say they do) when they are supposed to be taking 10

[admin]

Hi,

oops, I forgot to mention the 11 frame thing - that is sort of deliberate In live view mode, there's no real way of knowing whether the user covered the telescope for a dark frame just after an exposure started, and with longer exposures, that exposure might still be in progress when the user presses the 'Start' button. To avoid a possibly contaminated first dark frame, SharpCap takes an extra frame and discards the first frame. When the camera is in still mode, it's not strictly necessary, but at the moment it still captures the extra frame.

I have just checked the 605CC in still mode to make sure that there isn't an SVBony related still mode issue and don't see any problems. I will need to check the log file produced by SharpCap on your system to see if it holds any clues to what is going on.

thanks,

Robin

[nigeld]

ok just ran through capturing darks on both 4.1 and 4.0 with the intention of getting doesnt work and does work logs. However it looks like I was mistaken and it doesnt work in either.

Ive tried different usb settings and a port directly on the pc with the same result.

Now live view seems to work ok on both versions and so does the darks routine if i use the directshow driver.

Ive attached the logfile from 4.1

[admin]

Hi,

thanks for the log - it confirms pretty much what we suspected - after the first frame, SharpCap is having to wait double the expected time for each additional frame to arrive from the camera. I will raise this issue with SVBony and ask them to test to see if they can make the same happen. It doesn't look like an error that I will be able to fix in SharpCap (even if I had a 705C to test wtih).

thanks,

Robin

[nigeld]

ok thanks.

Weird that it works fine in live view mode.

Hopefully they are working on a new sdk/lib and could add the hdr option some other imx585 cameras have at the same time:)

[admin]

Hi Nigel,

in live view mode, SharpCap just sets the exposure and lets the camera get on with it. In still mode, every frame has to be requested from the camera by sending a request to start capturing an image and then SharpCap has to keep asking 'are you done yet?'. Looks like this approach has a bug of some sort for the 705C. Anyway, I've emailed my contact at SVBony and asked them to take a look.

cheers,

Robin

[nigeld]

Tried the ascom driver last night unfortunately this crashed sharpcap at the end of the exposure.

Actually just tried it with logging on and it crashed opening the camera.