Since different monitors can be brighter or dimmer at the same brightness level, you should first adjust them all individually until they match. By default, the F1 and F2 keys will only affect the active screen, but you can hold down Shift to control all displays at once. If you have more than one display connected to your Mac, you can control all of them individually or keep them in sync. However, if your monitor does not support gamma adjustment, an overlay mode is also available. The app works by modifying the gamma tables of each connected screen, as opposed to applying an overlay, which is what most similar apps do. Alternatively, you can access the app from the menu bar and check or alter brightness using your mouse. Once the app is up and running, you can use the F1 and F2 keys to lower and increase your screen’s brightness, just like on an Apple display. Simple and effective brightness adjustment It is designed as an alternative to Lunar for users who only need to alter brightness and perhaps don’t have a monitor that supports DDC. Gamma Dimmer is an attempt to make this function available on any monitor connected to your Mac. It is much more convenient than reaching for your monitor’s controls, but it is not supported by third-party displays.

One of the downsides of using third-party monitors is not being able to control your screen’s brightness using the keys on your Apple keyboard designed for this purpose.

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