I'm using an external monitor, so most of the time I've got the MacBook Air's internal screen dimmed to 0. But it doesn't switch off completely at 0 brightness as I can still see some graphical elements. They're hardly discernible but still there.

I was wondering if this is normal.

Unfortunately I couldn't find any other way to disable the built-in screen.


This is normal for LCDs that have the backlight off (which is what brightness at zero does), but which are still turned on. As far as I know, it's a side-effect of how LCDs work. The LCD screen itself turns the pixels on or off, but a CCFL or LED backlight behind the screen shines through to illuminate them. So while the backlight is off, the pixels are still active, just very hard to distinguish them.

I find on my old 2006 MBP, the Apple light from the lid leaks enough light that I can read a bit of text in the centre of my screen, even at zero brightness.

  • I see, ty for the explanation! seemed normal also to me, but it bothered me not knowing why. – user15322 Sep 19 '12 at 14:45

If you use only the second screen, you can safely close the lid of your MacBook Air and work only on the second screen, it will automatically switch it as the main and only screen.

  • Is this mountain lion thing? cause on lion, whenever I closed lid MBA would hibernate! – user15322 Sep 19 '12 at 14:45
  • No, if you are plugged to an external screen, it should automatically change. Make sure second screen is already recognized (the blue flash) and that you can use it and everything should change so it becomes main monitor. – Philippe Gilbert Sep 20 '12 at 12:12

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