Screen savers have been around since the early days of personal computers. They were originally designed to prevent an image from becoming permanently etched into a CRT's phosphorus, a phenomenon known as burn-in.
Burn-in is no longer an issue with computer monitors, so for the most part, screen savers don't serve any useful purpose, but there's no denying that they can be interesting and fun to watch.
You can access your Mac's built-in screen saver from the Desktop & Screen Saver preferences pane.
Open the Desktop & Screen Saver Preferences Pane
- Click the ‘System Preferences' icon in the Dock, or select ‘System Preferences’ from the Apple menu.
- Click the ‘Desktop & Screen Saver’ icon in the Personal section of the System Preferences window.
- Click the ‘Screen Saver’ tab.
The Screen Saver has three main areas: a list of available screen saver modules a preview window that shows what a selected screen saver looks like; and various controls and buttons for configuring the selected screen saver.
The Screen Saver area contains a scrollable list of screen saver modules. The list includes the modules provided by Apple, as well as any third-party screen savers you may install. In addition to built-in or third-party screen savers, you can select an image stored on your Mac to serve as a screen saver.
When you select a screen saver module or image, it will display in the Preview section of the Screen Saver tab.
The Preview window displays the currently selected screen saver, showing you how the screen saver will look once it's activated. Just below the Preview window are two buttons: Options and Test.
- Options. Click the Options button for a dropdown sheet of the options available for the currently selected screen saver module. Options vary from module to module; typical options include speed, the number of items to display, and how often an image cycles. If you select a folder of images to use as a screen saver, the options include displaying the images in random order, cross-fading between slides, zooming back and forth (similar to the Ken Burns effect of imparting the appearance of movement to a still image), cropping a slide to fit the screen, and keeping slides centered.
- Test. Click the test button to immediately activate the currently selected screen saver on your monitor. You can stop the screen saver by moving the mouse or clicking any key on the keyboard.
Screen Saver Controls
The screen saver controls in OS X 10.4 and OS X 10.5 are slightly different; 10.5 has a couple of additional options.
- Use random screen saver. Your Mac will randomly select a screen saver module each time it activates the screen saver function.
- Hot Corners. Click this button for a dropdown sheet that allows you to assign one or more corners of your display as hot corners. When the mouse cursor moves into a hot corner, the assigned function will be performed. You can use the dropdown sheet to assign a corner to start or disable the screen saver.
- Start screen saver. The ‘Start screen saver’ slider determines how long your Mac must be inactive before the screen saver kicks in. Use your mouse to slide the indicator to the number of minutes you want your Mac to wait before activating the screen saver.
OS X 10.5's Additional Controls
- Show with clock. This option will superimpose a digital clock over the active screen saver.
- Main screen only. If you have more than one display connected to your Mac, you can have the screen saver appear on all of the displays or just the main display.
Once you make your selections, you can close the Desktop & Screen Saver preferences pane.
One thing to note: If the activation time you set in a screen saver is longer than the time to sleep specified in the Energy Saver preferences pane, you'll never see the screen saver because your Mac will be asleep before the screen saver can activate. Check the setting in the Energy Saver preferences pane if your monitor goes blank instead of displaying the screen saver.