Nikon D300 User Manual page 220

camera will maintain the normal range of ISO settings in
sensitivity auto
low-noise, sharp masterpieces. However, at times the light
may be so low that the ISO may exceed the normal range of
200–800 and will start getting into the noisier ranges above
ISO 800.
Just be aware that
push your camera's
noisier images when light levels drop, if you've allowed it.
Use it with this understanding and you'll do fine. ISO
the maximum, unless you have set the maximum to a lower
number. Make sure you understand this or you might get
some noisy images.
ISO sensitivity auto control
powerful Nikon cameras. Maybe not everyone needs this
failsafe feature, but for those who do it must be there. I will
use it myself in circumstances where getting the shot is the
most important thing and where light levels may get too low
for normal ISO image-making.
Even if you think you might only use it from time to time, do
learn how to use it for those times. Experiment a bit with
sensitivity auto
control, so your images will be their normal
ISO sensitivity auto control
ISO sensitivity
control. It's fun and can be useful!
220
into a range that causes
is yet another feature of our
ISO
can and will
3200 is
ISO