Nikon D3s Technical Manual page 26

Exposure
Choose the following ISO sensitivity settings:
ISO sensitivity auto
control: On
In this example, ISO sensitivity will automatically be raised
to a maximum of ISO 12 800 if optimal exposure can not
be achieved at ISO 200. In modes
be raised only if the shutter speed required for optimal
exposure would be slower than 1/500 s (slower speeds will
be used if a speed of 1/500 s would still result in underexpo-
sure at ISO 12 800).
22
ISO sensitivity: 200
Maximum
sensitivity: 12 800
Auto ISO Sensitivity Control
Minimum shutter
speed: 1/500 s
e and g , sensitivity will