Nikon D300 Complete Manual page 315

Outdoor shots in overcast skies (6000K)
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ã Outdoor shots taken in shaded areas (8000K)
Individual Kelvin values can be set from 2500K to
K
10,000K
Manually set white balance using a white or
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neutral object (Nikon doesn't specify a range, but
we know that you can manually adjust a D300
from 2500K to 10,000K, so the range should be at
least that wide)
Note: Digital cameras fare less well using the Automatic white
balance setting with light that falls under 4000K (note that
Nikon doesn't recommend Auto below 3500K for the
D300; yet I find that even at 4000K the camera tends to set
a white balance that's a bit too high in Kelvin for the light).
That's partially because the blue sensors receive very little
information at these so-called "warm" color temperatures,
so the minute amount of blue wavelengths being seen by
the sensor becomes a factor.
One novel way of coping with the problem of getting good
automatic white balance with indoor light is to simply do
what we used to do with film: use an 80B filter! The 80B
shifts the 2900K color temperature of a 100-watt bulb up to
about 4300-4400K (an 80A would push it above 5000K),
putting it within the range the camera handles well.
Tip: Nikon's choice for normal outdoor lighting (5200K) should
raise eyebrows, though I haven't seen anyone specifically
comment on it. Daylight film is usually balanced to 5400K,
and many digital photographers set their default daylight
value even higher. (The origin of the 5400K number, by the
way, is interesting—it's the average measurement of color
temperature, taken at noon on summer and winter solstice
on the Mall in Washington DC in 1926! Since altitude, time
of day, time of year, cloud cover, and distance from the
equator all alter daylight color temperature, one value does
not apply to every situation.) Don't be afraid to experiment
a bit to find the white balance you like best. In general, I
find that Flash a2 is the quickest way for me to set a sunny
white balance I like, and I also tend to use much higher
Thom Hogan's Complete Guide to the Nikon D300
V1.02
Page 315