Screen brightness return default

The Automatically adjust brightness box, which you have checked, set the brightness to what the senor thinks is the best brightness for the lighting - which is the 'default' brightness. There is not one set brightness default.

The functioned doesn't seem to work properly. If I turn up brightness all the way, then turn on "Automatically adjust brightness," the brightness does not decrease to the appropriate ambient lighting. It stays super-bright. When I'm working on a picture and accidentally hit a brightness key, I would like to have a return to default. Unfortunately, the auto-setting doesn't do the trick.

There is no such thing as a brightness baseline or default. It's wherever the user wants it to be. Or, in the case of an ambient light sensor, the OS decides where to put it. But there is no fixed luminance point that is considered "standard".

I'm finding is that I sometimes hit the bright or dim buttons by accident and I want to go back to where the "auto" setting would put brightness (ie when the computer starts up or after sleep) for the current ambient light in the room. If I turn the sensor off and back on, the brightness doesn't change....seems to think where I last had it IS the default.

If I turn the sensor off and back on, the brightness doesn't change....seems to think where I last had it IS the default.

That is odd. It may be that you didn't manually/accidentally change it enough for the OS to assume it needs to readjust the brightness.

Once "Automatically adjust brightness" is enabled, brightness will adjust to the ambient light.

http://support.apple.com/kb/PH10969?viewlocale=en_US

Best.

There is no default setting for display brightness.

F2 key is not working?

But you can adjust it.

System Preferences > Displays > Display > Brightness

Best.

Did you ever get an answer to the default brightness for a Mac? It is strange not to have a baseline for this.

No - never got one. It should be built in.