Canon EOS-1D X Mark III Advanced User's Manual page 175

ISO Speed Range Used With ISO Auto
You can set the automatic ISO speed range for ISO Auto within ISO 100–102400. The
minimum can be set within ISO 100–51200 and the maximum within ISO 200–102400, in 1-
stop increments.
1.
Select [Auto range].
2.
Set [Minimum].
Select the [Minimum] box, then press <
Select the ISO speed, then press < >.
175
>.