An electronic flash that has a photocell which measures the amount of flash illumination reflected back by the subject. When enough light for a properly exposed picture is reflected to the photcell, it stops the flash from emitting more light.
Electronic flash unit that automatically adjusts flash duration based on flash-to-subject distance.
A flash system that automatically determines whether an image requires a flash and provides the correct amount of light; a typical feature on most digital cameras.
An electronic flash unit with a light-sensitive cell that determines the length of the flash for proper exposure by measuring the light reflected back from the subject.