Symptom
A built-in flat panel display dims. This may occur while watching a movie or slide show.
Solution
As an added feature of Energy Saver, a built-in flat panel displays dim after a period of inactivity equal to half the time required for the computer to go to sleep, as set in the Energy Saver pane of System Preferences. Because watching a movie or slide show does not count as activity, the display may dim while you are watching a QuickTime movie or slide show.
Dimming helps prevent image persistence that can be caused by an unchanging image, such as a login screen. There is no independent setting for display dimming in the Energy Saver preference pane. Pressing any key brings the screen back to full brightness, or wakes the computer.
If you want to prevent dimming while watching a movie or slide show, follow these steps:
1. Choose System Preferences from the Apple menu.
2. Choose Energy Saver from the View menu.
3. Set the slider for "Put system to sleep whenever it is inactive for" to Never.
4. Be sure the checkbox for "Separate timing for display sleep" is not selected."
Note: After viewing a QuickTime movie or slide show, you may wish to set the Energy Saver system preference back to your sleep preference, especially if you need to conserve battery life.
For more information, see technical documents:
106880: "
Mac OS X: Screen Saver Slide Show Goes Blank (or Black)"
88343: "
Apple Displays: Avoiding Image Persistence on LCD Displays"