Noise Being Introduced in Live Stack

[mikenoname]

I am using version 4.1.12741 and am having noise be added and amplified with each sub. I am using no enhancements. I have spent two long nights troubleshooting this problem and have eliminated darks, camera, power supply, light leaks, cables and anything else I can think of. I have included the log. The last three subs in the log are the ones pictured below.

Here is a screenshot of the first sub with only a small amount of noise on the right side of the histogram.

741 First Sub.jpg (512.04 KiB) Viewed 637 times

Here is the second sub with significant noise added.

741 Second Sub.jpg (565.17 KiB) Viewed 637 times

Here is the third.

741 Third Sub.jpg (588.33 KiB) Viewed 637 times

I then uninstall 741 and install 12717 and the problem disappears. As you can see this is a stack of 5 subs:

717 No Noise.jpg (485.59 KiB) Viewed 637 times

Log file:

Log_2024-11-08T21_39_44-11980.log

(91.21 KiB) Downloaded 21 times

I'm sure there's more you'll need but it's late and I'm tired and just wanted to get this posted.

Mike

[admin]

Hi Mike,

thanks for posting - I can see from the screenshots that the ones that show the noise in the histogram are also displaying the typical 'starburst' amp glow pattern of the 183 camera on the right hand side of the image. My conclusion from this is that the dark subtraction is either not working after the first frame or is somehow being disable after the first frame (the first frame image is fine, and I can see the dark being loaded up in the log, but unfortunately the log doesn't tell me if the dark got turned off or not.

I will test this out with a 183 camera here to see if I can repro the issue with just dark frames - I did make changes to dark subtraction in the last update to allow the new 'dark scaling' feature to be added, so I am worried that I broke something

cheers,

Robin

[admin]

Hi,

I have just tested and didn't find any problems with dark subtraction not working correctly on that version of SharpCap (phew), but I am able to get similar effects if I deliberately turn off dark subtraction after a few frames (amp glow appears and noise appears further right in the histogram - not as far right as yours though).

Did you save any files from the stack (or did it autosave?)? If you saved there will be a capturesettings.txt file that records the camera controls (including dark subtraction) at the point of the save - ie the end of the stack. If you have raw frame saving enabled then you could look at the raw frames to see if they all look similar or if there is a difference between the first and subsequent frames (like maybe the noise level of the camera changes for some reason we don't understand).

cheers,

Robin

[mikenoname]

Robin,

I do not save individual subs and did not save the stack, because it produced a lousy image (obviously). I guess I can uninstall 717, reinstall 741 and go out tonight and get what you need. Do you need just the text document from the final stack save? Anything else that will be helpful?

Mike

[mikenoname]

Robin,

Here is the file from the 3-frame stack I saved with 741 tonight. It seemed to behave the same noisy way as last night. I also saved raw images from it, though I'm not sure what I'm looking for.

Stack_32bits_3frames_900s.CameraSettings.txt

(3.24 KiB) Downloaded 24 times

stacklog.csv

(369 Bytes) Downloaded 28 times

Mike

[admin]

Hi Mike,

OK, thanks for the settings - they confirm that dark subtraction was still enabled as far as SharpCap is concerned at the point that you saved, with nothing else looking odd in the settings. I do see that you were using a flat frame, which I didn't try in my testing, so I will give that a go to see if it makes any difference.

If I don't find anything in that testing, I might need to ask you to share a set of files with me (dark, flat, 3 or so raw frames) so that I can test the same situation.

cheers,

Robin

[mikenoname]

Robin,

I have the master dark, flat and three raw files saved from that stack, so can send any/all of that you need, just let me know.

Thanks for looking into this!

Mike

[admin]

Hi Mike,

ideally, upload the files to something like google drive, one drive or dropbox and post the sharing link here. You could also try zipping them and emailing them to me (one file per email?). There is a 'contact us' link at the bottom of the page that will get emails through to me.

I now have another report of something odd with dark frames in this latest version (viewtopic.php?p=45896#p45896), but I am still struggling to catch anything misbehaving in my testing (tried with a flat yesterday as well as a dark and all was fine ...)

cheers,

Robin

[mikenoname]

Robin,

I have bundled it all up in a zip file on Google Drive:

https://drive.google.com/file/d/1KaNxrQ ... sp=sharing

The raw captures and all ancillary files the SC captures as well as the master dark and flat that was in use.

Mike

[admin]

Hi Mike,

thanks for taking the time to put that zip file together. I just downloaded it, but I couldn't find the raw frames inside (I found the dark, flat and some saved stacks). Don't worry though, since I had another set of files sent through from someone who had also bumped into the problem, and I think I now have a fix. Please try version 4.1.12766 from the normal downloads page (https://www.sharpcap.co.uk/sharpcap/downloads), which should fix the problem.

thanks for flagging this problem up - sorry that it took me so long to get to the bottom of it, but when I was testing with pure dark frame stacking I turned off 'Align Frames' since there were no stars to align on, and the align frames option was critical to the bug happening

Robin