Why does the screen change brightness level?

Flickers or changes it and leaves it there?

 

Loose logic board connector? That's the only thing that I can think of, but then the whole displayey part of the display would be having problems. Could be your backlight giving out...

 

I've had this problem myself. I went to the Genius Bar and of course they could no reproduce it. They still took my computer (Applecare FTW) and sent it out for repair. Apple replaced just about everything and it still happens to this day.

 

I also have the same problem. Changing the screen brightness back to the previous level doesn't work, since as it just goes back to the old brightness settings in 30 sec -- a few minutes. I find the brightness being changed on my MBP to be very annoying. I thought initially it might be the light sensor for the backlit keyboard that was doing it, but it was not. Anyone else notice how the macbook air keyboard backlight is triggered from the iSight camera and on the MBP it is _under the keyboard_. I.e. you can't hold your finger over the iSight camera in order to engage the keyboard backlight controls. Which I _hate_. ) Can you put tape over the under-keyboard sensor somehow??

Ok. It is a feature. I just took a lamp and shined it over the keyboard and the screen started lighting up, then dimmed down when I took the lamp away. So dear readers, it appears you are in some lighting setting between two of the settings the MB(P) is using, and it keeps going between those two settings.

I still want to turn on the keyboard backlight by blocking off the iShit.

 

Solution

I encountered the same problem few days after I got my MBP. And I guess someone said in this thread about MBP trying to adjust brightness in response to ambience light level. I think THAT is the cause. However, this is too sensitive a response since I do not notice any change in ambience light level in my room if you know what I mean. Here is what I propose. Go to System Preferences and choose Displays. You would see a box "Automatically adjust brightness as ambient light changes" and most likely, it will be checked. Uncheck it and it should help. I just did that like 10 min ago and since then the screen has not flickered. Hope THIS is the solution.

 

you guys sure "Automatically adjust brightness" isn't checked, that'll do it if you put your hand over the sensor or something.

 

Lol, thats what I was just about to suggest...

- CaptHowie

 

MacBooks don't have a light sensor, that's only in the MacBook Pro.

 

AH! Thank you!!! I just got my MacBook Pro and noticed that the screen was changing based on where I had my hands (I was in a dim room). Now that I know about the option I am going to leave it on... it feel so much better knowing that it is a function and not a defect.

 

At least my Macbook (2.0GHz Alu) seems to have a light sensor.
If I put my hand in front of the iSight, the screen brightness changes if i have the auto adjust brightness setting on.

Just adding this reply to the thread for the record if someone, as me, would have had some time of wondering if there is something wrong with their MacBook screen or with their eyes...

Lucky me it was neither ;-)

 

How to Turn Off Automatic Brightness

I assume you are using OS X 10.6. I had the same issue on my Macbook Pro. While i didn't experience "flickering", I did notice changes in brightness while typing an email. At first I thought I just might be going crazy. But it seems that just moving toward and away from the screen through changes in my posture was enough to trigger a change in ambient light as far as the computer was concerned. Another compounding factor was that I had turned off the main overhead light in the room above the computer table. A few feet behind and above me, I had two skylights turned on so small movements on my part really affected the amount of light getting to the computer's sensor, wherever that might be.

I was able to find the setting to change it to manual brightness. Here's how to do it:

Go to System Preferences | Displays | Displays tab
just under the Brightness slider is a checkbox for "Automatically adjust brightness as ambient light changes." Uncheck that, and the problem should stop.

I must admit, it's a neat feature, but I like to adjust brightness settings manually, especially if I'm working on some graphics.