Nikon D300 Complete Manual page 250

• If the difference in brightness across the entire matrix
meter is minimal (by definition, a low contrast scene), the
matrix metering is nearly perfect (and the meter tends to
use what it sees in the central region as the primary
measurement, almost like center-weighted metering).
Indeed, even color variations tend to be exposed correctly
in this situation
• Nikon's matrix meters tend to underexpose off-center
subjects in very high contrast situations, especially so if
the subject is outside the autofocus sensor areas.
However, since the D300's autofocus areas extend across
so much of the image area, this isn't as pronounced in the
D300 as in other cameras, and I don't see it at all if the
autofocus system has moved the focus point off center to
that subject.
• Overall scene brightness plays a part in the final camera
metering decision. Nikon once tried to build a diagram of
how brightness and contrast information interacted, but it
was very confusing and didn't reveal much detail useful to
the casual photographer. The key point that diagram
revealed was that in very bright and very dim scenes the
camera sets exposure differently than in "normally" lit
scenes. If I had to characterize this, I'd do so as follows:
• In very dark scenes, the central region (e.g. the center-
weight circle) is often considered the most important,
and exposure is sometimes biased towards what is
seen there. Lesson: be careful with very off center
subjects in low light. Anything outside the autofocus
sensing areas is what I consider off-center, so keep the
AF sensors over the critical area for exposure.
81 A "middle yellow value" doesn't have the same reflectance as a "middle gray
value," or a "middle red value" for that matter. The color ability of the Nikon matrix
meter corrects for this, however. If your subject is a big gray blob filling most of the
image area, the gray blob will be placed near the midpoint in the dynamic range of
the camera. If your subject is a yellow parakeet filling most of the image area, the
parakeet's yellow will be placed near the midpoint in the dynamic range of the
camera. Why "near" and not "at"? Because Nikon tries to account slightly for
perceptual differences between colors.
Thom Hogan's Complete Guide to the Nikon D300
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