3Custom Function SettingsN
C.Fn III: Autofocus/Drive
C.Fn-4 AF-assist beam firing
Enables or disables the built-in flash’s AF-assist beam or the EOS- dedicated external Speedlite’s AF-assist beam.
0:Enable
The AF-assist beam will be emitted when necessary.
1:Disable
The AF-assist beam is not emitted. This prevents the AF-assist beam from disturbing others.
2:Enable external flash only
If an external Speedlite is attached, it will emit the AF-assist beam when necessary. The camera’s built-in flash will not fire the AF- assist beam.
3:IR AF assist beam only
When an external Speedlite is attached, only with infrared AF- assist beam will be emitted. This prevents the AF-assist beam from firing as a burst of small flashes.
With an EX-series Speedlite equipped with an LED light, the LED light will not automatically turn on for AF-assist.
If the external Speedlite’s [AF-assist beam firing] Custom Function is set to [Disable], this function’s setting will be overridden and the AF-assist beam will not be emitted.
C.Fn-5 Mirror lockup
0:Disable
1:Enable
Prevents mechanical vibrations in the camera caused by the reflex mirror action (mirror shock), which can disturb shooting with super telephoto lenses or close-up (macro) shooting. See page 147 for the mirror lockup procedure.