Digital Photography Composition For Dummies

Sometimes I use one-shot autofocus when I shoot fashion images. I ask a model to step into a specific area, lock my focus on that area, and then ask him to back up and walk toward me. I take the shot when he reaches the area of focus. This way I get a natural walk from him and achieve sharp focus.

Continuous autofocus: When photographers shoot subjects in motion, they usually use a setting designed to track movement and automatically adjust focus accordingly. Nikon refers to this setting as continuous, and Canon refers to it as AlServo. (Read your owner's manual to find out which autofocus settings your camera has and exactly how to use them.)

Continuous focus allows you to focus directly on a moving subject by leading it. Leading a moving target refers to aiming ahead of it in order to make up for the distance it will travel. The continuous focus setting causes your camera to focus ahead of your subject based on how fast the subject is moving. Leading is best for shooting unpredictable subjects that are likely to be moving.

Composing subjects in motion

Most often, photographers compose images of moving subjects based on the direction in which they're moving. The general rule is to provide more space in front of the subject than behind it. This space in front is referred to as active space. It gives the subject room to move into the frame and gives viewers a sense of where the subject is going.

Figure 16-1 shows an example of active space in a composition. You may often follow this example, but remember that each situation is unique and should be photographed accordingly. Look for what's most interesting in telling the story of your subject. Perhaps where the subject came from is more interesting than where it's going. For instance, a rally car kicking up a trail of dust behind it could create interesting lines and shapes.

Because action is part of the message when photographing a subject in motion, be on the lookout for compositional elements that help give the sense of movement. Here are some elements that can help you:

Lines: Lines are a great tool for emphasizing and hinting at movement. They lead people's eyes in certain directions. Try to compose your scenes so the compositional lines assist in moving a viewer's eyes in the direction of the suggested motion.

Supporting elements: These elements help tell the story of why a subject is in motion or where it's going. If, for example, a runner is giving it everything she has, you may find it helpful to show the finish line that's motivating her. Or you can reveal the runner behind her who's causing her to push it.

Image format: Whether your composition should have a vertical or horizontal format is an important decision to make. If the subject is moving in a horizontal direction, a horizontal format may work best. If it's moving vertically through the scene (as a space shuttle might), a vertical format may tell the story better. For more on horizontal and vertical formatting, check out Chapter 11.

28mm, 1/640 sec, f/U, 320

Figure 16-1: The space provided in front of the subject shows the extreme length of the rail he's attempting to slide across.

Deciding whether to freeze or show motion

When you're photographing a subject in motion, you have the option to freeze or show the motion. Each situation is different, so you have to decide which way to go. I describe the methods in the following sections.

Producing sharp detail by freezing motion

When you want the maximum amount of clear and sharp detail in your photographs, you want to freeze motion as much as possible. Some situations where you may want to freeze motion completely include the following:

' Your subject has made impact with a liquid and created a splash, and you want to capture the effect.

• The details in your subject (which is moving) and background need to be clear for your message to be effective.

' A water drop is falling from a leaky faucet, a rock face, or a melting icicle.

' You're photographing an explosion or a bullet passing through something.

You freeze motion primarily by shooting with a fast shutter speed. The quicker your subject is moving, the more you should speed up your exposure time. An exposure time of 1/250 second is a good starting point for freezing motion in most cases, and it's the maximum speed in which most cameras can still sync with a flash. So, if you're shooting with a flash, you shouldn't go any faster than this unless your camera is capable. (Refer to your owner's manual to find out the max sync speed of your camera.) If you're shooting with available light, you don't have to worry about sync speeds, and you can shoot as fast as your camera allows.

Keep in mind that your shutter speed also controls your exposure (in combination with your aperture and ISO, which I cover in Chapter 3). So, if your exposure setting is 1/250 second at f/11 with an ISO of 200 and you speed up your exposure from 1/250 to 1/500 second, you need to open the aperture 1 stop to f/8 or raise the ISO 1 stop to 400 in order to compensate for the 1 stop loss of light. When the aperture is opened up all the way and using the maximum ISO, you'll be limited as to how fast you can shoot while maintaining a proper exposure. The brighter a scene, the less you have to worry about this dilemma.

Freezing the motion caused the drama in Figure 16-2. This image shows that the kite surfer just did a trick at a high speed with a lot of power behind it. The spray helps to suggest movement.

Showing motion Blur

Motion blur occurs when your shutter speed is too slow to freeze the motion of your subject. As a result, your image doesn't have sharp focus and may include some streaking. Sometimes motion blur ruins the outcome of a photo, but you also can use it to tell the story of a subject in motion more effectively. The relationship between your subject and your shutter speed determines how much motion blur you have in your image.

200mm, 1/500 sec, f/B, 320

Figure 16-2: Capturing the moment by freezing time.

Results vary when it comes to motion blur. The more practice you have, the more reliably you can predict the results. You can slightly blur a person walking down the street with a 1/30-second shutter speed. Depending on how fast or slow the person is moving, however, this technique could cause results that appear out of focus rather than blurred by motion. In order to emphasize the motion in his walk, a 1/15-second shutter speed may work better.

The slower your shutter speed, the less identifiable the subject and the stronger the emphasis on the motion that's happening. A car going 35 mph down the street may start to streak at 1/60 second.

In the following sections, I discuss capturing motion in light (fireworks, headlights, and so on) with long exposures. I show you how to create an effect that captures detail in your subject while causing the environment around it to streak with motion. I also explain how to combine the techniques of freezing motion and motion blur in one image.

Streaking fights

One interesting way to use motion blur is to shoot long exposures at night in order to capture moving lights. In Chapter 10, for example, I discuss the

technique of setting your camera on a tripod for long periods of time to photograph star trails. This technique also works with cars passing through your scene. Composing a frame of a winding road with the city or mountains in the background provides a great opportunity to practice with this method. Take some practice shots to make sure you have the correct exposure and an effective composition. When a car is about to enter the scene, start your exposure.

You want the car to enter and exit the scene during the time of the exposure. Doing so gives the sense that the car passed through the scene. If your exposure stopped before the car exited the scene, it would seem as though the car stopped in your image. Plan your shutter speed accordingly.