E-TTL II Flash System
E-TTL II will reward you with more accurate exposures in tricky circumstances – such as recomposed shots, or where the appearance of high or low reflective objects in the frame would otherwise result in over- or underexposure.
The EOS 30D features Canon’s E-TTL II for consistently accurate flash exposures when working with the camera's internal flash or any EX series Speedlite flash unit. This advanced distance-linked flash algorithm takes into account factors such as lens
distance information from compatible EF lenses, ambient light readings and the detection of reflective objects in order to calculate flash output.