My issue is Microsoft Word- that is associated with the hardware when installed so cannot be used with the newer iMac. I just got a newer 27' iMac (late 2013), and wanted to keep only one full size keyboard. I use Yosemite (OS 10.10) with mid-2012 MacBookPro and late 2009 iMac 27'. The suggestions work on some Macs but not others. Click on it's icon and it will allow you to adjust the brightness of 3 separate, connected displays/monitors. Install this app and a dark screen icon will be added to your menu bar at the top right of your screen.Ĥ.

Instead of experimenting save time and go to the App store and purchase a program called ScreenDimmer.ģ.

When I use my iMac as an external/additional display/monitor for my new Macbook Pro I can't control the brightness of my iMacs screen through the Macbook pro.Ģ. The whole F2 thing does not work so don't waste your time.ġ. The only thing that works is a display port cable with dual male ends. Don't use a Thunderbolt cable to connect the old iMac's display port. I have a late 2015 Macbook pro and I wanted to use my late 2009 i7 iMac as my monitor.ġ. I had the same issue as everyone in this forum. Just in case people end up here looking for a solution for adjusting the brightness of an external monitor or iMac when connected to a macbook pro.

Adjust brightness mac second monitor