Canon MARK IV User Manual (en)

Custom Function Settings
C.Fn II -9     LCD panel illumination during Bulb
0: Off
1: On during Bulb
If the LCD panel illumination is on (p.116) and you take a bulb exposure, 
the illumination will continue until the bulb exposure ends. This is 
convenient when you are taking a bulb exposure in low light and want to 
check the exposure time.
C.Fn II -10     INFO. button when shooting
You can change what is displayed on the LCD monitor when you press the 
<B> button while the camera is ready to shoot.
0: Displays shooting functions (p.23)
Displays shooting functions as found on the 
top LCD panel and in the viewfinder.
While the shooting settings are displayed, 
you can press the <W> <o> 
<Q> <Y> <Z> <O> or <S> 
button to display the respective function 
screen and turn the <6> or <5> dial to 
change the setting.
1: Displays camera settings (p.246)
Displays the camera settings.