Canon EOS-1D X Mark III Advanced User's Manual page 115

5.
Set the exposure and take the picture.
Exposure Compensation with ISO Auto
If the ISO speed is set to " " (AUTO) for manual exposure shooting, you can set exposure
compensation ( ) as follows:
With [ : Expo comp (hold btn, turn
Quick Control screen
Caution
Exposure may not be as expected when ISO Auto is set, because the ISO speed is
adjusted to ensure standard exposure for your specified shutter speed and
aperture value. In this case, set the exposure compensation.
Exposure compensation is not applied in flash photography with ISO Auto, even if
you have set an exposure compensation amount.
Note
In < > mode with ISO Auto, <
meter. mode after focus] set to the default setting (
button halfway will lock the ISO speed after focus is achieved with One-Shot AF.
When ISO Auto is set, you can press the <
If you press the <
level difference on the exposure level indicator compared to when the <
button was pressed.
Any existing exposure compensation amount is maintained if you switch to <
mode with ISO Auto after using exposure compensation in <
< > mode (
To coordinate exposure compensation in ½-stop increments with ISO speed set in
⅓-stop increments when [
comp ½-stop] and used with ISO Auto, exposure compensation is further adjusted
by adjusting shutter speed. However, the shutter speed displayed will not change.
Check the exposure level indicator and set the desired shutter speed
and aperture value.
< > or < > is shown at the ends of the exposure level indicator if
the exposure level exceeds ±3 stops from standard exposure.
> button and recompose the shot, you can see the exposure
).
1: Exposure level increments] is set to [½-stop, Exp
)] in [ 6: Custom Controls] (
> (Evaluative metering), and [
), holding down the shutter
> button to lock the ISO speed.
115
)
2: AE lock
>
>
>, < >, or