C.fn5: Operation; Dial Direction During Tv/Av; Av Setting Without Lens - Canon EOS-1D X Instruction Manual

3 Custom Function Settings

C.Fn5: Operation

Dial direction during Tv/Av

Normal
Reverse direction
You can reverse the dial's turning direction when setting the shutter
speed and aperture.
In the <a> shooting mode, the turning direction of the <6> and <5>
dial will be reversed. In the other shooting modes, the turning direction
of only the <6> dial will be reversed. The <5> dial's turning direction
will be the same for the <a> mode and for setting the exposure
compensation.

Av setting without lens

You can set whether the aperture can still be set when no lens is attached
to the camera.
OFF: Disable
ON: Enable
You can set the aperture with the camera even while no lens is attached.
This is convenient for studio photography when the aperture is already
determined, as you can set the aperture beforehand.
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