I use the automatic display brightness function in the System Preferences and I have noticed that it is doing totally wrong. When I turn the feature off and set the brightness to let‘s say maximum and turn the feature on again, the maximum will be used as the standard lighting. So when I set the maximum in a dark room, it will stay this bright. I tired it with 90 % brightness. When I open my windows to let light into the room, it goes up to 100 % and by closing the windows to a totally dark room it‘s going back to the 90 %. And sometimes when I set it to like 10 %, the iMac doesn‘t even react to my flash light. After a little time of tweaking around it works again.

I have restarted the iMac a couple of times, but it didn‘t help at all.

How can I fix that stupid behavior? My iPhone does fine. It uses the real ambient lighting.

What i did is to cover the sensor, set the brightness to as low as possible and activate automation. Putting the hand away set it to an optimal level. Is this how it‘s done?

– iMac Late 2015 27" (Mojave up-to-date, freshly installed a week ago)

– iPhone 8 Plus (iOS up-to-date)

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    I have to say that i've re-read a couple times, and it still doesn't make sense. Maybe you can link to what is the documented expected behavior for your os/hardware, and then also break-out each thing you tried/failed in its own block. 'Simplifying' by packing it into narrative sentences is just making it harder to follow exactly what you did. – New Alexandria Jun 22 '19 at 18:20
  • Independent on whether I activate automatic lighting or not, I have to set the brightness slider to what the standard for my room darkness is. It doesn‘t scan it automatically. I hat to adjust the „reference“ by myself and this is my problem. When I put the full brightness on and it‘s very dark, macOS saves this super bright light for my dark room, but it doesn‘t get dark when it‘s actually dark here. – Fixman Jun 22 '19 at 18:49

I found the solution: How to reset the System Management Controller (SMC) on your Mac

Simply turn the Mac off, pill the power chord for 15 seconds and connect and start it again. The brightness is now properly responding to the environment. I will better not touch the slider again.

  • Nevermind. Nothing is working and the second time the fix didn‘t work at all. – Fixman Jun 23 '19 at 14:46

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