I have a 2010 iMac 27 as well as a 27 Apple Cinema Display. The iMac will auto-dim on inactivity, I'd say around 5 minutes. When the iMac dim's the Cinema Display is still bright. There is no Automatically reduce the brightness of the display option in Energy Saver or Displays within System Preferences. Anyone any suggestions? CLI commands would be preferred.
Automatically dim the backlight of a secondary monitor on MAC
osx;display settings