—Christopher Robinson, Editor
Photographic lighting is primarily an exercise in reflection management. Understanding and managing reflection, for the result the photographer wants, is good lighting. We will look at how subjects reflect light and how to capitalize on those reflections.
Types Of ReflectionLight can reflect from a subject as diffuse reflection, direct reflection or glare. Most surfaces cause some of each of these three types. The proportions of each type of reflection vary with the subject, and it is the proportion of each reflection in the mix that makes one surface look different from another. For now, we do not care what type of light source might be producing any of the following examples. Only the reflecting surface matters. Any sort of light, strobe, tungsten or fluorescent could work.
Diffuse ReflectionDiffuse reflections are the same brightness regardless of the angle from which we view them. This is because the light from the sources is reflected equally in all directions by the surface it strikes. Figure 1 shows a diffuse reflection. In it we see light falling on a small white card. Three people are pointing their cameras at it.
If each of these individuals were to photograph the white card, each of their pictures would record the subject as the same brightness. On film, the image of the card would have the same density in each negative. Neither the angle of illumination of the light source nor the camera’s angle of view would affect the brightness of the subject in such a picture.
Other than in lighting textbooks, no surfaces reflect light in a perfectly diffuse manner. However, white paper approximates such a surface. Now look at Figure 2. Notice that the scene contains a mostly white piece of sheet music.
There is a reason that we chose to put the white newsprint in this particular example. All white things produce a great deal of diffuse reflection. We know this because they appear white regardless of the angle from which we view them. (Walk around the room you are in now. Look at the white objects and the black objects from different angles. Notice that the apparent brightness of the black objects may change with viewpoint, but the white objects stay about the same.)
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