Canon EOS 20D Instruction Manual

145

3 Custom Function SettingsN

Fully automatic flash photography for all conditions, from low light 
to daylight fill-flash.

The flash is averaged for the entire area covered by the flash. 
Since automatic flash exposure compensation will not be 
executed, you may have to set it yourself depending on the scene. 
This also applies if you use FE lock.

When a slow shutter speed is set, you can capture a light trail 
following the subject. The flash fires right before the shutter closes. 
This Custom Function can be used to obtain 2nd-curtain sync 
effects even with EX-series Speedlites which do not have this 
feature. If the EX-series Speedlite has this feature, it will override 
this Custom Function.

This works in the shutter-priority AE (Tv) and aperture-priority AE 
(Av) modes. If the subject’s brightness changes suddenly and the 
current shutter speed or aperture becomes unsuitable, the shutter 
speed or aperture is shifted automatically to obtain a suitable 
exposure.

When 2nd-curtain sync is used, a preflash will be fired for flash metering 
control right after you press the shutter button completely. Remember that 
the main flash will fire right before the shutter closes.