Canon EOS-1D X Mark III Advanced User's Manual page 929

ISO Speed in Movie Recording
The maximum limit is not expanded when the camera is set for RAW movies, even with
[Max for Auto] set to [H(51200)], [H(102400)], or [H(204800)].
In < > / <
The ISO speed will be set automatically within ISO 100–25600.
Setting [Max for Auto] in [
the maximum speed in the automatic setting range to H1 (equivalent to ISO 204800).
The minimum speed in the automatic setting range is ISO 200 when [
tone priority] is set to [Enable] or [Enhanced] (
expanded, even when expansion is set in [Max for Auto].
The minimum speed in the automatic setting range is ISO 400 when [
settings] is set to [On] (
In < > mode
With ISO speed set to [
25600.
When ISO Auto is set, setting [Max for Auto] in [
[H1(204800)] (
(equivalent to ISO 204800).
ISO speed can be set manually in a range of ISO 100–25600. Note that setting [ISO
speed range] in [
maximum speed in the manual setting range to H1 (equivalent to ISO 204800).
The minimum speed in the automatic or manual setting range is ISO 200 when [
Highlight tone priority] is set to [Enable] or [Enhanced] (
expansion is set, the maximum limit will not be expanded.
The minimum speed in the automatic setting range is ISO 400 when [
settings] is set to [On] (
Caution
Expanded ISO speeds are not available when the camera is set for RAW movies.
> / < > mode
: ISO speed settings] to [H1(204800)] (
).
], the speed is automatically set in a range of ISO 100–
) expands the maximum speed in the automatic setting range to H1
: ISO speed settings] to [H1(204800)] (
). ISO 100–320 represents an expanded ISO speed (L).
). The maximum limit is not
: ISO speed settings] to
929
) expands
: Highlight
: Canon Log
) expands the
). Even when ISO speed
: Canon Log
: