Your webcam cover is messing up your screen brightness

by @edent | # # # | 4 comments | Read ~309 times.

Here’s something I didn’t know – but should have, because it’s obvious… Your screen’s auto-brightness depends on your webcam. If, like me, you have a privacy cover – this happens:

The MacBook I’m using doesn’t have any lux sensors that I can see – most phones have a separate sensor which means the camera isn’t in use all the time.

What I find curious is that the camera’s hardware light isn’t on. It turns on when an app is accessing the camera – but not when the OS is.

A laptop with the webcam covered - a green LED is visible.

Is that a security hole?

Anyway, if you’re wondering why your screen isn’t adjusting its brightness correctly, uncover your webcam. If you’ve got nothing to hide…

4 thoughts on “Your webcam cover is messing up your screen brightness

  1. Mo says:

    I’m pretty sure the light sensor is distinct from the camera in a MacBook; there’s no way to activate the the camera without turning on the light on without dicking around with the firmware. with the exception of this kind of malware (which are now pretty difficult on modern macOS with System Integrity Protection enabled, as it by default), camera covers are largely pointless on Macs.

  2. Neil says:

    Hmm… I’ve used webcam covers on all my MacBooks (Air, Pro, MacBook), and haven’t noticed a problem with this.

    It might depend on the model? I’m tying this on a MacBook Pro, with the webcam cover in place. If I put my thumb slightly to the right of the webcam, that triggers the screen brightness change. But the cover alone is fine.

    Or — perhaps more likely — it might be that you need a smaller webcam cover? I use these (currently showing as unavailable), as they are both very small and very thin (so don’t affect the unit closing properly): https://www.amazon.co.uk/gp/product/B01J8UO94U/

  3. Alex Gibson says:

    Low tech solution proposal:
    MacGyver your existing slide cover by drilling a hole in it where the camera lens is, and covering that with Scotch Magic tape or anything else handy that is translucent, but not transparent.
    Or if you have access to a 3D printer (I’m happy to help) This cover could be printed (more smoothly than the designer did!) in translucent natural PLA: https://www.thingiverse.com/thing:2814505

  4. Huh, fair! It looks like there’s one right here, with some tiny perforations, so I guess the cover is affecting that? ¯\_(ツ)_/¯ src: osxdaily.com/2011/09/22/key…


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