Backlighting
Photographing backlit subjects can be a very
frustrating task, but it is also the type of light that produces some
outstanding images by making the subject look colorful and brilliant against
a dark background. You can also create silhouettes by exposing for the
lighting behind the subject.
The process of calculating exposure in backlit lighting is actually very
simple and not at all frightening. If you want all the detail , just meter
the most important part off the subject and work in stops. Some people use
the Sunny f-16 rule (see Exposure)
and then open up 1 or 2 stops to get proper exposure. I like to eliminate
guess work and get exactly the shot I want. I simply spot meter the area I
want in perfect exposure then work in stops by adding or reducing light. If
my subject is medium tone, I spot meter that area and shoot. I get a well
exposed shot against a dark background. If my main subject is lighter than
medium tone, I add light, or do the opposite if my subject is darker than
medium tone. It's that simple.
The actual color of the subject is irrelevant. It could be red, blue, brown
or whatever other color. If the subject is medium red, medium, blue, or
medium brown for instance, my exposure would be the same. I'd spot meter the
medium tone area and shoot. For lighter reds, blues, or browns, I'd add one
or two stops depending on how light I would want my subject to be. For
darker reds, blues, or browns, I would reduce my exposure by one or two
stops.
Right
Image:
I spot metered the white feathers on the great egret and then opened up
1-1/2 stop.
This is the fastest and most accurate way of photographing backlit subjects.
You could shoot in multi-segment or multi-pattern metering (they are the
same thing) mode and get fairly good results some of the time, but spot
metering gives you absolute control over the whole composition.
Above: The rim light effect around the leaves is the result of
exposing for this area and opening up 1 stop.
You should not add nor reduce exposure in multi-segment metering mode since you have no idea how each area in the frame was calculated by the camera. If your camera for instance, uses 9 segment metering, it divides the frame into 9 different areas and then calculates the light in each of these areas to come up with an average exposure. How much light your camera adds or reduces from each area in unknown. If you add or reduce exposure manually, you could easily underexpose or overexpose an area or more. Spot metering eliminates guess work by selecting what is really important to you to create a bold poster like image against a dark background. If you prefer a silhouettes, just expose for the light behind the subject and work in stops. Add or reduce exposure to create the effect you want.
Recommended reading:
Understanding Exposure: How to Shoot Great Photographs with a Film or
Digital Camera
More than 100 vivid, graphic comparison pictures illustrate every point in this classic and can help any photographer maximize the creative impact of his or her exposure decisions. Peterson stresses the importance of metering the subject for a starting exposure and then explains how to use various exposure meters and different kinds of lighting. The book contains lessons on each element of the triangle and how it relates to the other two in terms of depth of field, freezing and blurring action, and shooting in low light or at night. A section on special techniques explores such options as deliberate under-and over-exposures, how to produce double exposures, bracketing, shooting the moon, and the use of filters. Understanding Exposure demonstrates that there are always creative choices about how to expose a picture - and that the decision is up to the photographer, not the camera.