Canon EOS 600D - Manual (Page 52)

A Fully Automatic Shooting (Scene Intelligent Auto)
52
Although it is daylight, the flash popped up.
For a backlit subject, the flash may pop up to help lighten the
subject’s dark areas.
In low light, the built-in flash fired a series of flashes.
Pressing the shutter button halfway may trigger the built-in flash to
fire a series of flashes to assist autofocusing. This is called AF-assist
beam. Its effective range is about 4 meters/13.1 feet.
Although flash was used, the picture came out dark.
The subject was too far away. The subject should be within 5
meters/16.4 feet from the camera.
When flash was used, the bottom part of the picture came out
unnaturally dark.
The subject was too close to the camera, and a shadow was created
by the lens barrel. The subject should be at least 1 meter/3.3 feet
away from the camera. If a hood has been attached to the lens,
remove it before taking the flash picture.