Canon EOS-1D Mark IV - Manual (Page 212)

Custom Function Settings
C.Fn I -14 Apply shooting/metering mode
While holding down the <*> (AE lock) button, you can switch to the
regtsiered setting (shooting mode, metering mode, shutter speed, aperture,
or exposure compensation),
Disable: Pressing the <■)(■> button will lock the exposure (AE lock).
Enable: By holding down the <■)(■> button, you can instantly switch to the
registered setting.
Register: Set the desired setting for the AE lock button: Shooting mode,
metering mode, shutter speed, aperture, or exposure
compensation.
When you select
[Register], [With AE lock button (AF on/AF
off)] will be displayed where you can set the < ■)(■ > AE lock button
to also execute AF or not. Select [AF on/AF off] to register the
setting to the camera.
Q This setting cannot be registered if the shooting mode is set to “Bulb”.
C.Fn I-15 Flash sync, speed in Av mode
You can set the flash-sync speed for flash photography in the aperture-
priority AE (Av) mode.
0: Auto
The flash sync speed is set automatically within a range of 1/300 sec. to
30 sec. to suit the scene’s brightness. High-speed sync can also be
used.
1: 1/300-1/60 sec. auto
Prevents the sync speed from being set too slow under 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.
2: 1/300 sec. (fixed)
The flash-sync speed is fixed to 1/300 sec. This more effectively
prevents subject blur and camera shake than with setting 1. However,
the background may come out darker than with setting 1.
if When 1 or 2 is set, high-speed sync cannot be used with an external
Speedlite.
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