Depth by Layers
Last week we demonstrated what could be done with the warm color and side lighting to illuminate features to the east of a setting sun. This image, taken 48 minutes earlier than last week’s image, shows a different effect that can be achieved in the light of the setting sun.
The nearly horizontal light produces almost detailless silhouettes of the features in the canyon. Particulate matter in the air causes the light to scatter. The more air you look through, the more light-scattering there is, and the lighter the tone of gray of any feature behind that air. With this light-scattering effect, you get a depth-by-layers look, as near features are closer to black and the farthest features approach white, and features are almost posterized to a particular gray level corresponding to their distance from the camera.
Exposure for such a shot is somewhat difficult for most automatic-exposure cameras. The dynamic range (the difference in light level between the lightest and darkest features) is usually quite wide and, depending on how much sky or foreground is in your frame, an automatic-exposure camera will make the picture darker or lighter in an attempt to make the average of the scene a middle gray. Using a spot meter and employing techniques of the Zone System would give much more control, but neither the spot meter nor mastery of the technique are available to most photographers. Fortunately, there are some things that can be done to help control the lighting. First, if your camera has this capability, try to get as small a spot-meter reading as possible, and meter for a feature that you would like to see rendered as middle gray (around the middle of the tonal scale). Once the meter reading has been obtained, lock the corresponding exposure. If need be, you can put your camera into manual-exposure mode to effect this lock. Locking the exposure will make for consistent exposures regardless of how you might re-aim your camera. Second, shoot in RAW format. This preserves a lot more of the tonal information in the highlights and shadows. Third, use a RAW processing program, such as Adobe Lightroom (or Camera RAW) to adjust the mapping of pixel values to tonal values. In the Develop module of Lightroom, you’ll see an histogram (a count of pixels at the various tonal values) with peaks at the left (dark) and right (light) end of the tonal scale. The “Recovery” slider will pull the higher values down, recovering some of the detail in the sky; the “Fill Light” slider will pull the lower values up, recovering some of the detail in the shadows. The effect can be dramatic.
A luxury of using a digital camera is that there is no marginal cost for taking more pictures (“the film is cheap”), so experiment with different exposures, and take more pictures as the sun gets lower and lower in the sky. As is shown here, the light-scattering effect is pronounced and good sunset photography can be done even an hour before the actual setting of the sun.
Tip of the Week
2007.07.30
