Nikon D300 Complete Manual page 312

OK button to select it.
To turn Active D-Lighting off, repeat the above and select
Off in Step 4.
Some important things to note when using Active D-
Lighting:
• It was designed to work with matrix metering. If you
switch to another metering type, you get variable results.
• The camera never tells you when it is and isn't active.
Other than looking in the SHOOTING menu, you can't
tell whether you've set Active D-Lighting or not, and you
can't tell whether it's active or not (see first bullet).
• It doesn't change the exposure in Manual exposure mode.
Active D-Lighting only changes the zero point in the
metering bar in Manual exposure mode.
• Some Picture Control settings are canceled. Any
Brightness or Contrast setting is overridden by Active
D-Lighting.
• Automatic ISO and exposure compensation settings still
apply, if set. You can get really confused if you start
setting multiple things that influence exposure
simultaneously. If you don't believe me, set the camera to
Manual exposure mode, then turn on ISO sensitivity
auto control, dial in an exposure compensation, and set
Active D-Lighting; try to figure out what's changing the
exposure and by how much in that situation.
• The Active D-Lighting function is designed to work on
high contrast scenes. If you use it on a low contrast scene,
Thom Hogan's Complete Guide to the Nikon D300
V1.02
Page 312