How to disable automatic exposure changes

[rrettich]

Greetings,

First time post - please let me know if changes are needed, thx

Equipment: C9.25/AVX/ZWO585MC
Target: Moon 96%
Process: Manual mosaic

Is there a way to stop SHARPCAP from changing exposure settings automatically between captures? I am not sure if it's SHARPCAP or the camera, but when I change my target position to a lighter or darker section of the moons surface, the capture appears to automatically adjust as well. My settings are configured (where possible) WITHOUT the automatic options, at least where I know to disable them. The result is that some sections cannot be joined evenly into the mosaic because the white balance or exposure seems to have been changed automatically.

When I combine the images in ICE it 'seems' to do a decent job of blending, but I would rather not need ICE to have to adjust lighting and exposure if possible.

In the attachment you can see consecutive captures where SHARPCAP (Or the camera?) automatically increased exposure on the second capture.

Many thanks!
Richard.

temp.png (71.28 KiB) Viewed 6676 times

[admin]

Hi Richard,

SharpCap shouldn't change the camera settings for you unless one of the 'auto' options is turned on. For the ZWO cameras there is auto exposure ('Auto' checkbox) and auto gain (a toggle button with 'Auto' on it rather than a check box) - check that both of those are off. There are also 'Auto' options for the white balance controls which might just cause the brightness to change if they try to adjust the balance.

If none of that helps, please post the 'Capturesettings.txt' file that is saved alongside the captured video - that records all the camera setting, so it is possible to check for anything else that might cause the issue.

cheers,

Robin

[rrettich]

Thanks very much for accepting my question and for your response.

I was very careful to check that the GAIN and EXPOSURE settings were not 'automatic' but, I clearly overlooked something. I also suspect it has to do with the Auto White Balance which I have not yet played around with. If it is that setting, or a different setting in the camera configuration (ASI585MC) I would very much appreciate any advice you can offer.

Although the camera today is no longer configured as it was 4 days ago, I do see the White Balance sliders with an AUTO option, and I can't guarantee that those were not set to AUTO for this session.

Here's the Camera Settings text from one of those captures - they should all be the same setting for the entire session.

Best regards,
Richard.

[ZWO ASI585MC]
FrameType=Light
Pan=0
Tilt=0
Output Format=SER file (*.ser)(Auto)
Binning=1
Capture Area=3840x2160
Colour Space=RGB24
Temperature=32.5
Hardware Binning=Off
High Speed Mode=On
Turbo USB=100(Auto)
Flip=Vert
Frame Rate Limit=Maximum
Gain=95
Exposure=6.5100ms
Timestamp Frames=Off
White Bal (B)=78(Auto)
White Bal (R)=46(Auto)
Brightness=79
Auto Exp Max Gain=300
Auto Exp Max Exp M S=30000
Auto Exp Target Brightness=100
Mono Bin=Off
Trail Width=3
Minimum Trail Length=100
Trail Detection Sensitivity=9
Remove Satellite Trails=Off
Background Subtraction=Off
Planet/Disk Stabilization=Off
Banding Threshold=10
Banding Suppression=0
Apply Flat=None
Hot Pixel Sensitivity=5
Subtract Dark=None
NegativeDisplay=0
Display Black Point=0.10546875
Display MidTone Point=0.390358230217685
Display White Point=0.9921875
Notes=
CPWI=RA=23:30:15,Dec=-09:29:34 (JNOW)
TimeStamp=2023-08-04T08:00:47.2604115Z
SharpCapVersion=4.0.9538.0
StartCapture=2023-08-04T08:00:47.2338650Z
MidCapture=2023-08-04T08:01:47.2218650Z
EndCapture=2023-08-04T08:02:47.2097265Z
Duration=119.976s
FrameCount=1520
ActualFrameRate=12.6692fps
TimeZone=-7.00

[admin]

Hi,

well, the gain and exposure are definitely on manual in that configuration, but the white balance settings are on auto. You may wish to turn those off of auto and put them back to 'neutral' defaults (50 and 50). Although the colour will look wrong - probably green/yellow cast - with those settings, it will be the raw digital data coming from the sensor with no processing, so the best way to capture. You can then tweak the colour balance easily after processing stacking without having an existing tweak built into the captured data.

The other thing I can suggest is to go to the downloads page and grab the very latest SharpCap 4.0 which has a ZWO software update in it compared to the 4.0.9538 that you are using - just possible that there was some issue with the 585 (which is a relatively new camera) that has now been fixed by ZWO.

cheers,

Robin

[rrettich]

Hey Robin,

Thanks so much for the detailed responses. Very much appreciate the help!

I will definitely try turning off the AWB and set the levels to 50/50. I do appreciate know this is 'camera raw' levels and I will be able to adjust colours in post. I'm not convinced the 585 is my best option for lunar due to its larger sensor and lower frame rate but I'm not prepared to throw in the towel just yet. I will also d/l the update you mentioned.

We are dealing with alternating rain clouds and wildfire smoke these days (BC, Canada) so I will need to wait a bit before trying out these suggestions.

Thanks again for the help!
Richard.