Canon EOS REBEL XS Instruction Manual page 64

Custom Function Settings*
C,Fn [[[: Auto focuslDrive
The AF-assist beam can be emitted by the camera's built-in flash or by the
external, EOSodedicated Speedlite.
O: Enable
1 : DieabJe
AF-assist beam not emitted.
2: Only externa_ flash em{te
ff an external EOS-dedicated Speedlite is attached, it will emit the AF-
assist beam when necessary. The camera's buHbin flash will not emit
the AF-assist beam.
If the external; EOS-dedieated Speedlite!s [AF,assist beam firing] Custom
Funotion is set to [Disabled], the SPeedlke will not emit the AE_assist beam
even if the camera's C.Fn-6-0/2 is set,
When 1 or 2 is set, AF will be possible during Live View shooting. For
details, see pages 102- 106_
0: Disable
1: Quick mode (p.102)
2: Live mode (p.104)
0: Disable
1 : Enable
Prevents camera vibrations caused by the reflex mirror action which can
disturb shooting with super telephoto lenses or close-up (macro)
shooting. See page 94 for the mirror Iockup procedure.
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