Canon EOS-1DX Instruction Manual page 105

VF display illumination
The AF points and grid in the viewfinder can be illuminated in red when
focus is achieved.
Press the <Q> button to set the AF points to be illuminated in red
(blink) during AI Servo AF.
The setting here is not applied to the electronic level display (p.61) in the
viewfinder.
Blinking interval depends on the shooting conditions.
The AF points and grid will always be illuminated in red when you press
<S> for AF point selection.
3 Customizing AF Functions
AUTO: Auto
The AF points and grid are automatically
illuminated in red under low light.
ON: Enable
The AF points and grid are illuminated in
red regardless of the ambient light level.
OFF: Disable
The AF points and grid are not
illuminated in red.
OFF: Non illuminated
AF points are not illuminated in red
during AI Servo AF.
: Illuminated (Normal)
AF points used for focusing are
illuminated in red during AI Servo AF.
The red illumination takes effect when
[VF display illumination] is set to
[Auto] or [Enable].
: Illuminated (Brighter)
The function is the same as that of
[Illuminated (Normal)]. However, the
illumination is brighter.
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