Canon MARK IV User Manual (en)

Exposure compensation can increase (brighter) or decrease (darker) 
the standard exposure set by the camera.
You can set the exposure compensation up to ±3 stops in 1/3-stop 
Exposure compensation can be set in the <d/s/f> shooting modes.
Check the exposure.
Press the shutter button halfway and 
check the exposure level indicator.
Set the exposure compensation 
Set the power switch to <J>, and 
while looking at the viewfinder or top 
LCD panel, turn the <5> dial.
Turn the <5> dial while pressing the 
shutter button halfway or within (9) 
after pressing the shutter button halfway.
When exposure compensation has 
been set, the <y> icon will be 
displayed in the viewfinder.
To cancel exposure compensation, set the 
exposure level indicator <s> to the 
standard exposure index (<a> or <C>).
Take the picture.
 Exposure Compensation
Increased exposure
Decreased exposure
If [8C.Fn II -4: Auto Lighting Optimizer] (p.81) is set to a setting other 
than [3: Disable], the image may still look bright even if the exposure 
compensation is decreased.
The exposure compensation amount will remain in effect even after you 
set the power switch to <2>.
Be careful not to turn the <5> dial and change the exposure compensation 
inadvertently. To prevent this, set the power switch to <1>.
You can also set it by pressing the <O> button and turning the <6/5> dial.