Canon EOS Rebel XS Instruction Manual page 72

Custom Function Settings*
C.Fn ill: Auto focus/Drive
The AF-assist beam can be emitted by the camera's builtqn flash or by the
external, EOS-dedicated Speed]ire
0: Enable
1: Disabme
AF-assist beam not emitted.
2: O_my external fl_sh emits
if an external, EOS-dedicated Speedlite Js attached, Jtwill emit the AF-
assist beam when necessary. The camera's bu It-in flash wil} not emit
the AF-assist beam.
If the external, EOS-dedicated Speed]ite's lAP-assist beam firing] Custom
Function is set to [Disabled], the SpeedJ!te wil} not ernff the AF-assist beam
even if the c_mera's C.Fn-6-0/2 is set.
When 1 or 2 is set, AF wil_ be possible during Live View shooting For
details, see pages 102 - 106
O: Disabme
1: Quick mode (p.102)
2: Live mode (p 104)
0: Disabme
1: Enable
Prevents camera vibrations caused by the reflex mirror acflon which can
disturb shooting with super telephoto }crises or close-up (macro)
shooting See page 94 for the mirror Iockup procedure
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