Display Brightness Changing on its Own.

[David Eichler]

I have a dual-display setup with an iMac running OS 13.6.4. I have the outboard display set as the main display when both displays are on. When I turn off the power to the outboard display, the brightness of the iMac display changes on its own to near maximum brightness, which I do not want. Is this a bug, or am I missing something? I only started using this set up recently.

[degrub]

what happens if you switch the iMac display to main ?

[digitaldog]

Try resetting the NVRAM:
https://www.lifewire.com/troubleshooting-mac-display-problems-4121097

[David Eichler]

Try resetting the NVRAM:
https://www.lifewire.com/troubleshooting-mac-display-problems-4121097

Thank you. That seems to have worked,

[David Eichler]

Actually, turns out it only worked temporarily. The problem came back. Also, I have done a clean install in the meantime and the problem still persists. Will have to look for other solutions.

[BobShaw]

Have you turned of the Display setting "Automatically Adjust Brightness"

[David Eichler]

Have you turned of the Display setting "Automatically Adjust Brightness"

No serious photo editor should use that feature.    So, yes, I have it off.

[degrub]

black tape over the camera or other sensor used by the imac to auto adjust brightness ?

[David Eichler]

black tape over the camera or other sensor used by the imac to auto adjust brightness ?

Even if I were using auto brightness, since I am editing in a room with low ambient light, it should adjust the monitor brightness lower, not to maximum brightness, which is what is happening with my computer.