Canon EOS 1D Software Instruction Manual page 197

Shortened release time lag
Normally, the shutter-release time lag is controlled for stability. This Personal Function
eliminates this control. As a result, the shutter-release time lag can be reduced by as much
as about 20 percent when the aperture needs to be stopped down by no more than 3 stops.
This is effective when a shorter shutter-release time lag is more important than a stable
shutter-release time lag.
Since the difference is in 10-millisecond increments, the time lag may not feel any
shorter.
Enables the electronic dial's function to be used in the reverse
direction
The electronic dial's rotational function can be reversed for selecting the AF point and
setting the shutter speed and aperture.
By matching the dial's rotation direction to the particular operation, the operation can feel
more intuitive.
When the main dial's rotational function is reversed, the horizontal AF point selection
direction does not change.
Prevents exposure compensation with the Quick Control Dial
The Quick Control Dial cannot be used to set exposure compensation.
This prevents exposure compensation from being set accidentally while the AF point is
being selected.
Enables Quick Control Dial switch to turn on/off Main Dial too
Setting the Quick Control Dial switch to <OFF> disables the Main and Quick Control Dials.
Personal Function Settings
M-73
M
4