Canon EOS Rebel XTI - Manual (Page 105)

3 Setting Custom FunctionsN
105
C.Fn-6 Exposure level increments
0: 1/3-stop
1: 1/2-stop
Sets 1/2-stop increments for the shutter speed, aperture, exposure
compensation, AEB, etc. Effective when you prefer to control the
exposure in less fine increments.
C.Fn-7 Mirror lockup
0: Disable
1: Enable
Effective for telephoto and close-up shots to prevent camera shake
caused by the mirror’s reflex action.
C.Fn-8 E-TTL II
0: Evaluative
Fully automatic flash photography for all conditions, from low light to
daytime fill-flash.
1: Average
Geared for advanced users who want to control the external Speedlite,
this mode averages the entire flash metering area. Since the camera
will not execute automatic exposure compensation, adjust the flash
exposure compensation if necessary.
The exposure level will be displayed in the viewfinder and on the LCD
monitor as shown below.