All photographers know, or quickly learn, that subject matter is only one element of a photograph and it is arguably not the most important element. Interesting or dramatic light is often the key ingredient of a successful image. When composing a photograph, it is important to pay attention to the direction the light is coming from and how this impacts the subject that is being photographed.
Look around for the source of the light and then take another look at the subject to see how the light is falling on it and how it changes as you move. Often by stepping to one side or another the lighting can be made more dramatic and interesting.
There are basically four types of directional light that are important to an outdoor photographer: sidelight, backlight, frontlight, and soft or diffused light. Here's a rundown on two types:
Soft light can be created by fog, overcast or shade and increases the color contrast in softer, subtler tonalities. Soft light enhances colors that would be lost or become to contrasty in direct sunlight. Soft light is best for subject matter that is colorful or has interesting detail such as flowers, plants or other types of close up images.
The two soft-light images below - the close-up of the lupine and the small waterfall near Yosemite were both taken in cloudy, overcast conditions. This type of light eliminates shadows, which reduces contrast and allows for more saturated, vivid colors. Neither of these images would have been successful if the sun had been shining on them.
Sidelight creates shadows by lighting one side of the subject while leaving the other side darker. This is a great light for textured subject matter such as rock cliffs, bluffs or for showing depth in sand dunes. Sidelight works well for subject matter where color is missing or not an important part of the image.
In place of color, the dark shadows created by sidelight often become an important element in the image, which makes sidelight very useful for shooting monochromatic images. Often when I am photographing along the coast at sunset I will turn to one side or the other to see the effect of the low, warm light instead of facing directly into the setting sun.
In the two side-light examples below, the dark shadow lines between the ridges of the sand dunes were caused by the sun being very low on the horizon. Shots that I took a few minutes later did not turn out as well because the sidelight had disappeared as the sun went lower. In the second image of sidelight in Yosemite, the rays of the sun are dispersed by smoke that was in the air from a controlled burn.
Note: Doug Steakley is a professional photographer who teaches for BetterPhoto's online digital photography school. Check out his online photography workshop: Photographing Motion