Nikon D300 User Manual page 120

ISO sensitivity can be set to values between ISO 200 and ISO 3200
in steps equivalent to 1/3 EV. Settings of from about 0.3-1 EV
below ISO 200 and 0.3-1 EV above ISO 3200 are also available for
special situations.
ISO sensitivity can be adjusted
by pressing the ISObutton and
rotating the main command
dial until the desired setting is
displayed in the control panel or
viewfinder.
IS0 button Main command
dial
Control panel Viewfinder
94
ISO sensitivity: 3200
[] The ISO Sensitivity Menu
ISO sensitivity can also be adjusted using the [ISO sensitivity] option in the
shooting menu (pg. 254).