Nikon F100 Instruction Manual page 45

w: Center-Weighted Metering
Center-Weighted Metering places special emphasis on brightness within
the 12mm-diameter circle in the viewfinder, so it is useful for basing
exposure on a specific area of the scene.
e: Spot Metering
Nearly 100% of the meter's sensitivity is concentrated on the 4mm-dia.
area (approx. 1% of entire frame) within the selected focus area of the
viewfinder. Use Spot Metering when you want to base the exposure on a
very small area within the frame, such as with a backlit subject or low-
contrast scenes. When Spot Metering is selected, shifting focus area also
shifts Spot Metering area to a corresponding position. However, Spot
Metering area stays at center (does not shift) as long as Dynamic AF Mode
with Closest Subject Priority (page 39) is activated or non-CPU lens (page
32) is attached.
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