Nikon COOLPIX 5200 Manual page 58

Choosing a Value for Exposure Compensation
As a rule of thumb, select positive values when large areas of the frame are very brightly
lit (for example, when photographing an expanse of sunlit water, sand, or snow) or
when the background is much brighter than the main subject. Choose negative values
when large areas of the frame are very dark (for example, when photographing a forest
of dark green leaves) or when the background is much darker than the main subject.
This is because the camera, in order to avoid extreme under- or over-exposure, tends
to lower exposure when the frame is very bright and raise exposure when the frame is
very dark. This can make naturally bright subjects look darker and naturally dark sub-
jects appear over-bright, or "washed out."
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