Does the Late 2013 15-inch MacBook Pro (Retina display) need both sensors to the left & right of the FaceTime camera in order to function correctly?

Are these both ambient light sensors? I usually don't use FaceTime nor do I allow the system to automatically adjust the levels of brightness.

If the two uses mentioned above are the only two purposes for these sensors, I wouldn't really need them, or at least not both of them right?

The problem is the screen protector I have, which was supposedly designed for the exact specs of this laptop; yet, it clearly covers the rightmost sensor. The slightest up, down, left, or right will leave one side short and the other side overlapping the bevel.

If both of them happen to be ambient light sensors, my question is, in order for the macbook and other apps to function properly are both sensors necessary? Please keep in mind the fact I don't use FaceTime and do not allow the system to auto adjust brightness as well.

Else, what are their purposes?

  • AFAIK they only have one sensor. Commented Mar 20, 2014 at 0:07
  • @Riegler Definitely two. I'm trying to take a picture but it is turning out to be quite difficult.
    – les
    Commented Mar 20, 2014 at 0:14

1 Answer 1


On my 2015 Macbook Pro, what looks like two ambient light sensors is actually a light sensor on the left of the webcam, and a green LED on the right of the webcam that lights up when Facetime is open to let you know the camera is in use.

The sensor on the left can be tested by waving a flashlight in front of it and observing the keyboard dimming. The light on the right can be verified by opening Facetime.

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