The Flickering Screen Issue
MacBooks are equipped with an ambient light sensor located near the webcam. By default, macOS uses this sensor to constantly monitor the lighting conditions in your room. If a cloud passes over the sun, or if you lean forward and cast a shadow over the sensor, macOS will instantly dim your screen. When you lean back, it brightens again. While this saves battery life and reduces eye strain in dark rooms, the constant, automatic flickering and shifting of screen brightness can be incredibly distracting—especially for photographers and video editors who require absolute color and brightness consistency.
How to Disable Auto-Brightness
You can turn off the ambient light sensor entirely, forcing the screen to remain exactly at the brightness level you manually select on your keyboard.
1. Click the Apple logo () in the top-left corner of your menu bar.
2. Select System Settings (or System Preferences on older versions).
3. In the left-hand sidebar, scroll down and click on Displays.
4. Look at the options for your built-in display.
5. Locate the toggle switch labelled Automatically adjust brightness.
6. Click the toggle switch to turn it Off.
What About True Tone?
Just below the auto-brightness setting, you will likely see a second toggle switch labelled True Tone. While auto-brightness changes the intensity of the light, True Tone automatically changes the color temperature (making the screen more orange in warm lighting, or more blue under fluorescent lights). If you are disabling auto-brightness because you need color accuracy for design work, you must also ensure the True Tone toggle is turned Off. Otherwise, your screen will stop flickering, but the colors will still silently shift based on the lighting in your room.