Nikon D300 User Manual page 125

B
Auto ISO Sensitivity Control
Noise is more likely at higher sensitivities. Use the [High ISO NR] option in
the shooting menu to reduce noise (see page 263). Foreground subjects
may be underexposed in photos taken with the flash at slow shutter
speeds, in daylight, or against a bright background. Choose a flash mode
other than slow sync or select exposure mode A or M and choose a larger
aperture.
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