Canon EOS-1D X Mark II DSLR Camera (Body Only) - Manual (Page 166)

i : Setting the ISO Speed for Still Photos
166
You can set the manually-settable ISO speed range (minimum and
maximum limits). You can set the minimum limit within L (equivalent to
ISO 50) to H2 (equivalent to ISO 204800), and the maximum limit within
ISO 100 to H3 (equivalent to ISO 409600).
1
Select [ISO speed settings].
Under the [ z 2 ] tab, select [ ISO
speed settings ], then press < 0 >.
2
Select [Range for stills].
3
Set the minimum limit.
Select the minimum limit box, then
press <
0 >.
Select the ISO speed, then press
<
0 >.
4
Set the maximum limit.
Select the maximum limit box, then
press <
0 >.
Select the ISO speed, then press
<
0 >.
5
Select [OK].
3 Setting the Manually-Settable ISO Speed Range