Nikon Z 6II Reference Manual page 59

❚❚ Movie Mode
ISO sensitivity can be adjusted by holding the S button and
rotating the main command dial. ISO sensitivity for movie
recording can be adjusted in mode M only.
•
The value selected for [ISO sensitivity settings] > [ISO
sensitivity (mode M)] applies when [Off] is selected for [ISO
sensitivity settings] > [Auto ISO control (mode M)].
•
You can choose between "ISO AUTO" (auto ISO sensitivity
control enabled) and "ISO" (auto ISO sensitivity control
disabled) by holding the S button and rotating the sub-
command dial.
Camera Controls
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