Accent lighting isn’t always necessary, but can be important, if not essential, in certain situations. If you use a dark background, dark hair and clothing may blend into the background if you do not use a background light or accent lights. A properly placed accent light provides separation between the subject and the background.
When lighting a background, place your background light where it will be hidden from the camera and at a position where it will illuminate the background without spilling onto the subject. For example, you can direct the background light toward the background from behind the subject, or from either or both sides of the set.
You can control how light or how dark a background will photograph by adjusting the relationship between the intensity of the background light and the intensity of the light falling on the subject. First, take a reading using an incident light meter from the subject position. If you want the background to photograph in its true tonality, that is if you want a light gray background to photograph as light gray, adjust the intensity of the background illumination until your meter reads the same as the subject reading. For example, if your subject reading is f/8, your background reading should also be f/8.
You can create a lighter background by increasing the intensity of the background light. If your exposure reading at the subject position is f/8, adjust the amount of light on your background until the meter reads f/16, and expose for the subject at f/8. Your background will be two stops overexposed and will appear much lighter than it really is.
You can create a darker background by reducing the intensity of the background light. For example, if your exposure reading at the subject position is f/8, adjust the intensity of the background light to f/5.6, expose for the subject at f/8 and your background will be one stop underexposed and will appear darker than it really is.
It is just as important to light a white background properly, because without the correct amount of light, a white background will photograph as a dirty gray, or perhaps a starker white than you desire. You may find that your background will photograph as a cleaner white if you add enough light to boost the background reading by 1/2 to 1 full f-stop.
Accent Light and Kickers
Accent lights are seldom absolutely necessary, but they can turn an ordinary portrait into one that is outstanding. The most commonly used accent light is a hairlight. Unless you use a hairlight, your subject’s hair may blend into the background and will probably photograph somewhat darker than it really is. When you use a hairlight you should adjust its intensity until your incident light reading is equal to or more intense that the subject reading. If the reading is equal or close to equal, you will get a natural effect with improved hair texture. If you choose, you can increase the intensity of the hairlight to produce a more dramatic effect.
Your hairlight should be placed high and slightly behind the subject and aimed toward the subject’s hair. You can use any type of light source as long as you can adjust it so that it reaches only those areas you want to illuminate. For example, you can use a strobe with a small reflector. You can also use a soft box or a small to medium-sized strip light fitted with louvers for more precise light control. Regardless of the type light you select, it is best to mount your hairlight on a boom, a track system or some other type of ceiling support system.
Hairlights aren’t the only type of accent lights. You can add an accent light, called a kicker, from any position that allows you to illuminate only the area you want to accent. For example, a kicker can be behind and to the side of the subject. This light can add a rim of light along the side of the subject’s face, adding interest and sparkle to the photograph.