Click to explore the main light.

Outdoors, the brightest source of light is usually the sun. In the studio, the role of the sun is performed by what's called the main light (or sometimes the key light). Like the sun it's the brightest source of light and casts the darkest shadows. There are two things to consider when placing the main light—it's position relative to the lens axis and its distance from the subject.

• When close to the axis of the lens, shadows are minimized. As the light moves further from the lens axis, shadows expand and become more prominent.
• As the light is moved closer to the subject, the light falling on the subject increases and you can use a smaller aperture. Also as you move it closer, it's relative size increases so the light becomes softer. It casts shadows with less defined edges and lowers contrast as it envelopes the subject in light.

Like the sun, this light is often positioned above and often slightly behind or to the side of the subject. Placing the light above the subject creates light on the subject that is familiar, as are the shadows it creates. Placing it below the subject often creates a mysterious, eerie looking effect. You'll see this lighting in horror and mystery movies, especially with bad guys. However, its position depends on the subject. If you wanted to bring out the dimples in a golf ball, you'd place the light farther away and rake the light across the surface of the ball. For a portrait, you might do exactly the opposite, moving it closer and more in front.