Exposure Metering System; Matrix Metering - Nikon N90 AF Instruction Manual

EXPOSURE METERING SYSTEM
The Nikon N90 has three type of exposure metering systems- Matrix Metering,
Center-Weighted Metering and Spot Metering .
MATRIX METERING
This system is ideal for quick operation in any exposure mode
(pp. 49-66). With D-type AF Nikkor lenses including AF-I Nikkor,
3D Matrix Metering is automatically activated. 3D Matrix
Metering uses three types of data: (1) scene brightness, (2)
scene contrast and (3) focused subject's distance (Distance
Information). Data on scene brightness and contrast are
detected by the camera's 8-segment Advanced Matrix Sensor,
while data on the focused subject's distance is detected and
relayed by the D-type AF Nikkor lens in use. In addition, the
information sent by the camera's autofocus system indicating
whether the main subject is centered is also considered in the
computation. By analyzing these data, the N90's built-in
microcomputer is able to provide correct exposure even in
extremely complex lighting situations.
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If a non-D-type lens is used, Advanced Matrix Metering is
performed. Although lens' Distance Information is not given, 8-
segment Matrix sensor provides the correct exposure in most
lighting situations.
Note that Matrix Metering system can be used only with lenses
that have a built-in CPU (such as AF Nikkor and AI-P lenses.)