Canon EOS REBEL T4I Instruction Manual page 19

Setting the Flash "_
[Flash sync, speed in Av mode]
You can set the flash-sync speed for
flash photography in the aperture-priority
AE (Av) mode.
® AUTO: Auto
The flash sync speed is set automatically within a range of 1/200
sec. to 30 sec. to suit the scene's brightness. High-speed sync is
also possible.
@ lJ20e .
-_,_0A. 1/200-1/60 sec. auto
Prevents a slow shutter speed from being set in low-light conditions.
It is effective for preventing subject blur and camera shake.
However, while the subject will be properly exposed with the flash,
the background may come out dark.
® 1/200:11200 sec. (fixed)
The flash-sync speed is fixed at 1/200 sec. This more effectively
prevents subject blur and camera shake than with [1/200-1/60 sec.
auto]. However, in low light, the subject's background will come out
darker than with [1/200-1/60 sec. auto].
e_ iii_oo,ii_0 _e_ _,t0i o r Eii_oo Sec. <fiXe,_ii issei: ,_g, s peed S_n_ is
not possible in the <Av> mode,
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