V1.02
Thom Hogan’s Complete Guide to the Nikon D300
Page 253
manual doesn’t point out the 75/25 split, but Nikon’s
technical specifications indicate the 75% value; the 25% is
inferred.) In other words, if the central area metered f/4 at
1/125 and the outer area metered f/16 at 1/125, the exposure
would be set somewhere around f/5.6 at 1/125.
Center-weighted metering
normally uses a circular area
about the same size as the green
area in illustration at left for 75%
of the metering value. The
remaining 25% of the meter value
is based on the area outside this
area (white area in illustration)
The central measuring area is normally 8mm (0.31”). You can
change the size of the central area by using Custom Setting
#B5 (see “Center-weight Circle Size” on page <541>), though
I personally don’t find this to be an overly useful feature.
One throwaway note in the Nikon literature should be called
out: if you’re using a filter that has an exposure factor of one
stop or more, use Center-weighted metering instead of matrix
metering. That would, for instance, apply to polarizing filters.
The reasoning behind switching metering types with strong
filters is simple: the matrix patterns were created using no
filtration. Strong filters can greatly alter what the matrix sees
in two ways: they reduce the overall brightness level, which is
something that the matrix system uses to determine what
pattern to use; and some types of filters have variable impacts
on different areas of the frame, altering the pattern the matrix
meter sees. For example, a polarizing filter can bring down a
bright sky value quite a bit without affecting foregrounds at
the same intensity. That means that the matrix pattern for
“landscapes with sky” might not be recognized as easily.
Spot
Most professionals tend to use spot metering when they
have enough time to do a critical evaluation of a scene. That’s
