Nikon D300 Complete Manual page 359

V1.02
-1 Brightness Lowering
the gamma tends to bring
mid-tone values down.
Look closely at the gray
scale patches on the
bottom of the
ColorChecker chart.
+1 Brightness Raising
the gamma brings those
same values up. Now that
gray scale ramp is so low
in value that the first two
values look similar
(though black still is
black).
Thom Hogan's Complete Guide to the Nikon D300 Page 359