Nikon D6 Reference Manual page 272

D
Auto ISO Sensitivity Control
•
If value currently selected for [ISO sensitivity] is higher than that
chosen for [Maximum sensitivity], the value chosen for [ISO
sensitivity] will serve as the upper limit for auto ISO sensitivity control.
•
During flash photography, shutter speed is limited to the range defined
by the values selected for Custom Settings e1 [Flash sync speed] and
e2 [Flash shutter speed]. If the value selected for [Minimum shutter
speed] is not in this range, the value selected for Custom Setting e2
[Flash shutter speed] becomes the effective minimum shutter speed.
•
If a non-CPU lens is used without lens data, the minimum shutter speed
will be fixed at
•
If an optional flash unit is attached, ISO sensitivity may be raised
automatically when auto ISO sensitivity control is used in combination
with slow sync flash modes, possibly preventing the camera from
selecting slow shutter speeds.
A
Turning Auto ISO Sensitivity Control On or Off
You can also turn [Auto ISO sensitivity control] on or off by holding the
S ( Q ) button and rotating the sub-command dial ( 0 116).
220
Adjusting the Camera's Sensitivity to Light (ISO Sensitivity)
1
/ s.
30