This is the big problem with backlighting – it’s not easy to get the right exposure. When the light source is behind the subject, the face of the subject is usually toward the camera, and it’s in shade. For example, let’s say you’re taking a picture of your father with the sun behind him because it produces a halo of his thinning white hair. When you take a meter-reading – either with your autoexposure camera or some other meter – the meter often reads the bright sun or sky behind him, and it “decides” that there’s plenty of light on the subject so you need minimal exposure. Result: A well-exposed sky…but your father is a dark silhouette. This is a frequent problem with backlit subjects – underexposure of the subject.
What should you do to get better exposure?
You have a number of options.
First, some cameras have a “Backlight Button.” If you hold this button down while you take the picture, the camera will override the exposure meter and open up the aperture a bit – usually, one stop or one-and-a half stops. This may solve the problem. But in really bright backlight – for example, in bright sun – it may not be enough. Since we usually can’t tell in advance, we at NYI try for a more controlled solution.
Second, you can move in close to take a meter reading. To do this, first decide what’s most important in the picture. Then, if it’s, say, your father’s face, come in close and take a meter reading of the face only. Don’t let the meter read any part of the bright sky. If you’re using an autoexposure camera, lock in this exposure before you step back and compose the shot. (Your camera’s manual will tell you how to lock in the exposure.) If you’re using a through-the-lens meter or a separate meter, come in close, get a meter reading of the face only, then use this setting as your exposure when you step back to take the picture. (If you are using a zoom lens, you may be able to accomplish the same result without moving. Zoom in tight so that the built-in meter sees only the face, and take its reading. Then hold this exposure setting as you zoom back to the full image.)
The second method is usually better than the first. But it’s not perfect because the exposure will be right for the face, but it will usually be too much for the bright background, so the sky will often burn out. If you don’t care about the sky, then this approach is fine. But what if the sky is filled with interesting puffy clouds. How can you record them as well as your father’s face? This brings us to the third option.
Meter for the sky. Then add light to your father’s face. How?
The easiest way may be to add fill flash. Your camera probably has a fill-flash setting. Use it. Or you can add light to the face using a reflector board. This is a bright – usually white or silvered – surface that reflects the sunlight back onto the face. You usually need an assistant to hold the reflector board, although your subject may be able to hold it without assistance. Either way, there are two tricks to using a reflector board properly: First, hold it close enough to the face to get sufficient light reflected onto the face. Try holding it at different distances, and watch the light on the face carefully. You may find that the effect you want will only be achieved when the board is just a few inches from the face. Which brings us to the second “trick”: Make sure the reflector board doesn’t show in the picture!
Whether you use fill flash or a reflector board, this technique of metering for the sky and then adding light to the face gives you the best of both worlds – the face can be properly exposed and the clouds can stand out in the same picture.