10. Light has color, even when it looks “white.” This is called color temperature, and our eye/brain computer is very adept at adjusting our perception so that we hardly notice it. Digital sensors and film, though, may record color casts where our eyes didn’t see them.

The color of early morning and late afternoon sunlight is warm in tone, while open shade at midday can be quite bluish. Tungsten light bulbs cast very yellow light. And any surface that light bounces off can add its color.

With digital cameras, you can use the white-balance control to neutralize color casts or to emphasize them—for example, to add a warmer tone to a landscape or portrait. With slide film, you had to choose the right film for the light you’d be shooting in, or compensate with filters.

Tip: Landscapes shot on clear days can be very blue, especially in the shadows. Set your camera’s color balance to Cloudy, which acts as a warming filter for a more golden glow.