Nikon D40 Manuel D’Utilisation

White balance ensures that colors are unaffected by the color of the light source.  Auto
white balance is recommended for most light sources; if necessary, other values can be
selected according to the type of source.  The following options are available in P, S, A, and M
modes (Auto is automatically selected in Digital Vari-Program modes): 

In addition to selecting white balance, the White balance option in the shooting menu can be used
to fine tune white balance, measure preset white balance, or copy a value for preset white balance
from an existing photograph.

White balance can also be set using the command dial.

Camera sets white balance automatically.  Recommended for most sit-
uations.

Use under incandescent lighting.

Use under fluorescent lighting.

Use with subjects lit by direct sunlight.

Use with built-in flash or optional Nikon flash units.

Use in daylight under overcast skies.

Use in daylight with subjects in the shade.

Use gray or white object or existing photograph as reference for white
balance (  70).