Most digital cameras come with a built-in flash. This usually can be set to fire automatically, in which case the camera will measure the lighting and engage the flash when you take a picture whenever the lighting level is too low.

Alternatively, you can set the flash to always go off, never togo off, or to go off in "Red Eye" mode, which fires a tiny pre-flash to let subjects' eyes acclimate to the light, thus reducing the dreaded "red-eye" effect.

Rebel: In any of the Creative modes, press the lightning bolt icon button at the left of the camera body. The flash unit will pop up, and the flash will go off when the next shot is fired. To turn the flash off again, press the flash unit itself down until it snaps into position. The flash cannot be turned off when the camera is in any of the Basic modes.

PowerShot _cameras: Set the flash by pressing the small button on the top left of the back of the camera that's marked with a tiny lightning bolt. As you press the button the options are displayed as icons in the upper left corner of the LCD screen. The options are:

• Lightning bolt icon with a tiny letter A for automatic flash
• Lightning bolt icon for always on flash
• Lightning bolt icon with a line through it for turning off the flash

If you find that your flash pictures come out too bright or too dark, you may want to manually adjust the flash intensity. This is especially relevant if you're shooting objects that are fairly close to you, or relatively far away.

Rebel: Press the Menu button and navigate to Shooting Menu #2. Access the "Flash exp comp" (flash exposure compensation) and use the arrow keys to raise or lower the flash intensity.

PowerShot G1: Press the "WB" button on the camera back repeatedly, until the scale on the LCD shows a flash icon. Then press the omni selector left or right to adjust the flash intensity up or down. Press the Set button to accept the new setting.

PowerShot G5: Press the FUNC button on the camera back, then use the down arrow on the omni selector to scroll down to the flash entry. Now scroll left or right to adjust the flash intensity up or down. Press the SET button to accept the new setting.

Most cameras can also accept high-quality aftermarket flash units, which will provide more full and even illumination. Consult your camera's documentation to see which flash unit to buy.