Nikon D300 User Manual page 192

To use active D-Lighting:
1
Select [Active D-Lighting].
In the shooting menu (pg. 254),
highlight [Active D-Lighting]
and press 2.
2
Choose an option.
Highlight [Off], [Low], [Normal],
or [High] and press J.
J
D
Active D-Lighting
When Active D-Lighting is on, the capacity of the memory buffer drops
and additional time is required to record images (pg. 406). Matrix
metering is recommended (pg. 100). Although exposure is in fact
reduced to prevent loss of detail in highlights and shadows, highlights,
underexposed areas, and mid-tones are automatically adjusted to prevent
the resulting photograph from being underexposed. The [Brightness] and
[Contrast] Picture Control settings (pg. 151) can not be adjusted while
active D-Lighting is in effect.
D
"Active D-Lighting" versus "D-Lighting"
The [Active D-Lighting] option in the shooting menu adjusts exposure
before shooting to optimize the dynamic range, while the [D-Lighting]
option in the retouch menu optimizes dynamic range in images after
shooting.
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