Nikon D300 - Manual (Page 310)

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d7: Shooting Info Display
At the default setting of [Auto] (AUTO), the color of the lettering in
the information display (pg. 12) will automatically change from
black to white or white to black to maintain contrast with the
background. To always use the same color lettering, select
[Manual] and choose [Dark on light] (B; black lettering) or [Light on
dark] (W; white lettering). Monitor brightness will automatically be
adjusted for maximum contrast with the selected text color.
Dark on light Light on dark