Previous 1 2 Next 27 Replies Latest reply: Mar 6, 2013 7:52 AM by digsoreos
Eric Westby Level 4 (1,815 points)

I've owned iPhones going back to the 3G, and as a result I'm fairly sure I know how the auto-brightness setting is supposed to work. (When the phone is powered up in a darkened room, the display is dimmed to a level appropriate to the ambient lighting.) At least that's how it's always worked until I started using my new iPhone 5! With my new phone, there's no perceptible difference between having the setting on or off. And before you say it, yes I know you have to turn the screen off and on again for the new brightness level to take effect.


Has anyone else noticed anything similar?

iPhone 5, iOS 6, 64GB, GSM/AT&T
  • tal1971 Level 2 (245 points)

    It works the same from what I can see.


    What I noticed the other day (which is how I would expect auto brightness to work). I was setting my iPhone 5 up. I was sitting with the sun shining through the windows (which was directly behind me). I had set the brightness level to around 75 percent, I had auto brightness on. When I went back into the brightness section again, due to the bright sunlight, I saw the brightness level move its self up to the maximum level. It done this because of the bright sunlight and so that it would be easier to read. This is exactly how I would expect auto brightness level to work, i.e dim itself when in a darkened room, and brighten up when in a well lit area.


    If you go into the section to alter the brightness, and set it at say 75 percent, put auto brightness on. Leave the screen on for the brightness section and go outside in the sunlight. You should see fairly quickly the brightness level go up all by its self. I forgot to mention that both my iPhone 5 and iPad 3 do this.

  • Pappasbike Level 3 (560 points)

    iOS 6 changed how the brightness functions on all my devices, iPhone 4, 4S, iPad. I don't have the 5 ( yet ), but I assume it;s the same. No matter what the brightness level had been set at when I locked the screen, when I first wake it up it is very dim then slowly adjusts it self to the necessary level based on ambient light. If ypou're in the brightness setting you can watch the slider move itself to the proper level.


    This is quite different from previous phones/operating systems where the screen would come on at previous brightness level and then adjust itself to the ambient light. I remember how it would always blind me if I woke it up in a darkened room!

  • Liquadia Level 1 (0 points)

    mine doesnt work after the update I cover then whole sensor or phone under heavy blankets it does nothing

  • Liquadia Level 1 (0 points)

    That does work for me though that brightness lift from dim to normal!

  • Eric Westby Level 4 (1,815 points)

    Fascinating. I can state unequivocally that mine does not work that way: even in a pitch black room, with auto-brightness turned on, it comes up 5x brighter than my other iDevices do. I guess a trip to the Genius Bar is in order. :^/

  • brentonfromhighton Level 1 (0 points)

    There is nothing wrong with the auto brightness.


    When you have auto brightness enabled the slider works as the minimum brightness setting with auto brightness.


    If you have the slider too high the brightness cant reduce because youre not letting it.


    Set your brightness at about 25% and you'll see what I mean.

  • Eric Westby Level 4 (1,815 points)

    With all due respect, I believe the auto-brightness function or the ambient light sensor on my unit is faulty. I know exactly how it is supposed to work; as I mentioned in the OP, I've owned several iOS devices. The brightness setting is almost all the way to the left.


    That said, I know you were just trying to be helpful, so thanks for your input.

  • Eric Westby Level 4 (1,815 points)

    An update to the thread: I went to the Genius Bar today, and the Genius confirmed that something isn't quite right: we pointed the unit directly into the sun with auto-brightness on, and it didn't get any brighter. He also found that if you turn the brightness all the way down to nothing, *then* turn auto-brightness on, the setting goes sort of haywire, changing positions seemingly at random.


    He went off to research the issue a bit on his super-secret database, and came back with the news that while others have reported it, and Apple is aware of the problem, there's not yet consensus on whether it's a hardware or software issue. It only seems to be affecting a small number of devices.


    Unfortunately his best advice was to wait for iOS 6.0.1, and if that doesn't resolve it, see once again about getting a hardware replacement. I guess I'll be manually changing the brightness in bed for a while! #firstworldproblems

  • ivan98 Level 1 (10 points)

    Refer to Figure 1 in


    Prior to iOS 6, the control function of Auto Brightness is pre-determined based on the Brightness slider value you set. Figure 1 shows 4 such curves; 1/4, 1/2, 3/4 and Max.


    In iOS 6, works/ propose that users can dictate their own brightness function.


    1. In ambient brightness of value a1, if you're not happy with the proposed brightness by the phone, you set it to some brightness level, say b1.
    2. In ambient brightness of value a2, if you're not happy with the proposed brightness by the phone, you set it to some brightness level, say b2.
    3. In ambient brightness of value a3, if you're not happy with the proposed brightness by the phone, you set it to some brightness level, say b3.


    From now on, each time the phone goes into ambient lighting of level a2, it will automatically go into brightness level b2.

  • Eric Westby Level 4 (1,815 points)

    Fascinating! Mine doesn't work quite the way described in Reddit; e.g., I go into a dark room and set it to my preferred level, leave. and return to the dark room, but the brightness does not change back to my preferred level.


    Still, this shows beyond a doubt that the way the sensor and related code work is completely new. Thanks,

  • fbzik Level 1 (10 points)

    Sensor works very well, both on 4S and 5 but people do not know how to set it correct.


    1. You need to set slider on minimum brightness

    2. Turn auto-brightness one ON/OFF and set it on ON, than it will adjust automaticly




    The auto-dim feature got significantly improved in iOS 6. The best improvement is brightness adjustment in the lock screen. Before, in a dark room, I would be blasted with the iPad or iPhone’s default brightness before sliding to unlock and having it dim down to match the room’s brightness. Now, from the moment the screen turns on, the brightness is appropriate.

    In all previous versions of iOS, the light sensor would sense the room’s brightness and then suddenly make the brightness adjustment. In iOS 6, the auto-brightness adjustment is gradual and much more subtle, like the Mac. "

  • thumper_net Level 1 (10 points)

    The auto brightness is an ios 6 bug , just seen cnets apple byte where they state the auto brightness does not work and they gave the whole ios 6 a bad apple , not a good start sadly

  • Eric Westby Level 4 (1,815 points)

    Could you provide a URL for the CNET story you referenced? I searched and came up blank.



  • thumper_net Level 1 (10 points)

    If you download the cnet tv app from the appstore you can watch the weekly podcast

    Iclick on shows and choose apple byte

    The story over ios 6 and iphone 5 and iphone 4s problems is


    Apple Byte:

    iPhone 5: Record sales, record frowns?

    Dated 27/09/2012

    There are plenty of other older videos to watch as well

    Its a good and sometimes funny weekly show

    Hope that helps

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