David Pogue's Digital Photography: The Missing Manual

Existing-Light Portraits

Cameras love light, that's for sure. And you may need the flash for indoor shots.

But not always. Some of the best interior photos use nothing more than light streaming in from a window. Pictures that use only ambient light without adding flash are called existing-light, natural-light, or ambient-light photos. They have numerous advantages over flash photography:

• More depth. The problem with the flash is that it illuminates only about the first 10 feet of the scene. Everything beyond that fades to black.

  In existing-light photography, on the other hand, your camera reads the lighting for the entire room. Not only is your primary subject exposed properly, but the surrounding setting is too, giving the picture more depth.

• Less harsh. The light in an existing-light photo generally comes from a variety of sources: overhead lights, windows, lamps, and reflections off walls and ceilings. All of this adds up to softer, more balanced light than what you get from the laser beam generated by your built-in flash.

• More expressive. Too often, flash pictures produce the "deer in the headlights" look from your subjects—if the close-range flash doesn't whitewash them completely. Existing-light pictures tend to be more natural and expressive, and the people you're shooting are more relaxed when they're not being pelted by bursts of light.

An existing-light indoor portrait has a classic feel, because it's reminiscent of those timeless paintings by great artists like Rembrandt. ...