Canon EOS M6 Mark II Advanced User's Manual page 111

If the "30"" shutter speed blinks, it indicates underexposure.
z
Turn the <6> dial to set a larger aperture (lower f/number) until the
shutter speed blinking stops or set a higher ISO speed.
If the "1/4000" shutter speed blinks, it indicates overexposure.
z
Turn the <6> dial to set a smaller aperture (higher f/number) until the
shutter speed blinking stops or set a lower ISO speed.
Aperture Value Display
The higher the f/number, the smaller the aperture opening will be. The f/number
z
displayed varies depending on the lens. If no lens is attached to the camera,
"F00" will be displayed for the aperture.
Checking the Area in FocusM
Press the button you have assigned to depth-of-field preview (using [ 8
C.Fn III-2: Customize buttons], ( = 537)) to stop down the lens to the
current aperture setting and check the area in focus (depth of field).
The larger the aperture value, the wider the area in focus, from the foreground
z
to the background.
Exposure is locked (AE lock) as you hold down the button assigned to
z
depth-of-field preview.
Pressing the button assigned to depth-of-field previewing when a Speedlite
z
470EX-AI is attached with the < X > switch set to < Z > (full auto) starts AI.B
full-auto distance measurement.
Aperture-priority AE Mode (Av)
:
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