Canon EOS 6D Instruction Manual page 326

8: Custom Controls
: Flash exposure compensation
Press <0> to display the flash exposure compensation setting screen
(p.170) on the LCD monitor.
: Image quality
Press <0> to display the image-recording quality setting screen
(p.102) on the LCD monitor.
: Picture Style
Press <0> to display the Picture Style selection setting screen (p.112)
on the LCD monitor.
: Depth-of-field preview
When you press the depth-of-field preview button, the aperture will stop
down and you can check the depth of field (p.147).
: IS start
With the lens' IS switch set to <1>, the lens' Image Stabilizer
operates when you press the button assigned to this function.
: VF electronic level
When you press the button assigned to this function, the viewfinder and
LCD panel will display an electronic level using the exposure level
indicator (p.61).
: Menu display
Pressing <0> will display the menu on the LCD monitor.
: No function (disabled)
Use this setting when you do not want to assign any function to the
button.
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