Photography: Painting with Light

The word, “photography” derives from the Greek language as “writing with light.” But I find it easier to think of it as painting with light. A photographer’s subject must be illuminated, and the color of the subject is determined by the color of the light striking it. There are many ways to change that color (choice of film, adjusting the white balance, etc.) but the starting point is the light source one is using and for the landscape photographer, that usually means the sun. So knowing what happens with sunlight at different times of the day as well as different times of the year helps me anticipate photographic opportunities before they happen.

The subject here is the Francis Scott Key Bridge, from a vantage point on the Washington, D.C. side of the Potomac River. Figure 1, on the left, was taken about 30 minutes before Figure 2. The latter, shot a few minutes before sunset on September 21, 2004 using Ektachrome VS 100 slide film. Anyone who lives in the Washington area knows that the Key Bridge is not painted gold. The normal color of the bridge is shown in Figure 1, but the color shown in the second image is as I saw it and not the result of a Photoshop technique. The magic lasted only a few minutes and probably was witnessed by only a few people, mostly boaters and the staff of the boathouse from whose dock the picture was taken.

All landscape photographers are aware that sunlight is composed of many colors (or wavelengths as the scientific folks would say). These colors are shown in a rainbow or when the light passes through a prism. We also are familiar with the yellow or red light that is often associated with a sunrise or sunset. The warm golden tone is caused is the fact that the sun is close to the edge of the earth’s horizon and the light must pass through a greater amount of the earth’s atmosphere. The air scatters the shorter wavelengths (violet and blue) while the longer wavelengths (yellow, orange, and red) pass through.


Knowing that a sunset can produce this effect, however, is not enough to capture an image like the one in this example. It is also necessary to know where the sun will set. In this case, the bridge runs almost due north-south (a bearing of 18 degrees east of north when crossing from Virginia), meaning that the upriver side faces almost due west. And September 21, 2004 was one day before the fall equinox when the sun sets precisely at due west. Therefore, I knew that for a few days around that date I had a good chance of capturing a image of the bridge being illuminated by a golden sunset.