Canon EOS R5C Manual page 696

C.Fn1
Exposure level increments
You can specify to use 1/2-stop increments as the increments for shutter speed, aperture
value, exposure compensation, AEB, flash exposure compensation, and FEB.
1/3: 1/3-stop
1/2: 1/2-stop
Note
Display when set to [1/2-stop] is as follows.
ISO speed setting increments
You can change the manual ISO speed setting increment to a whole stop.
1/3: 1/3-stop
1/1: 1-stop
Note
Even if [1-stop] is set, ISO speed will be automatically set in 1/3-stop increments
when ISO Auto is set.
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