Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 173)

ISO Speed Range When Set Manually
You can set the manual ISO speed setting range (minimum and maximum limits). You can
set the minimum limit within L (equivalent to ISO 50) to H2 (equivalent to ISO 409600), and
the maximum limit within ISO 100 to H3 (equivalent to ISO 819200).
1.
Select [ : ISO speed settings].
2.
Select [ISO speed range].
3.
Set [Minimum].
Select the [ Minimum ] box, then press < >.
Select the ISO speed, then press < >.
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