In the studio, you usually use more than one light to illuminate a portrait or product. The goal is often to create light that looks like that found outdoors. The lights can be hot lights, strobes, or slave flash units-or even fill cards. Sometimes you can get away with only one or two lights but the use of main, fill, background and rim lights is a classic studio lighting setup for portraits that can be adapted to other subjects.

• The main light is positioned somewhat to one side of the subject and somewhat above it.
• A fill light is placed opposite the main light, but more nearly at the subject's level.
• A background light is used to control the lighting on the background behind the main subject.
• A rim light is placed quite high and behind the subject to highlight edges and separate the subject from the background.

  For most purposes you can get by with just the main light and a fill light. In fact, you can often get along with just the main light by replacing the fill light with reflectors to bounce light into the shadows. The way you position a light relative to the subject is very important.

• As you move a light farther away from the subject you reduce the light falling on it. Because there is less light you may have to use a larger aperture which gives less depth of field.
• Moving a light back hardens its light, while moving it closer softens it. By moving a light farther away, you also reduce the light it illuminates the subject with. On strobes, you do it by adjusting the light's intensity. On continuous lights you can do the same with a dimmer switch. You can have one light illuminate the subject with more intensity than another light. The difference between the two lights is called the lighting ratio.
• Positioning the light at an angle to the subject will make the light uneven over the subject with the part closest to the light getting more light. The exposure will only be correct for those at one distance—normally those in the area metered by the autoexposure system. Parts of the setup located farther from the light source will be increasingly darker the farther away they are.