Capturing motion
When you want to catch a moving target through your camera lens, you can go in two creative directions: you can use a slow shutter and purposely blur the image to create a heightened sense of motion, or you can set the shutter speed high enough to "freeze" the subject at a particular instant in time. (Experienced photographers also know to claim that they were trying for the former if the latter doesn't work as intended.) This section provides some tricks to use for both approaches.
Speeding up your camera's response time
Using blur to emphasise motion
If your camera offers manual exposure control or shutter-priority AE (autoexposure), achieving the amount of blur you want is easy: just experiment with slower and slower shutter speeds until you're satisfied with the results.
Of course, as you reduce shutter speed, your camera senses light for a longer period of time. So you should also reduce aperture size (by shifting to a higher f-stop setting) to avoid overexposing the image. If your digital camera offers only programmed AE -- or programmed AE and aperture-priority AE -- you may be able to use these workarounds to get the slow shutter needed to produce the blur:
- In programmed AE, try switching to night-time scene mode, if available. As discussed earlier, this mode typically forces a slower shutter. Warning: you may wind up with too much light in your image.
- In aperture-priority AE, set the f-stop to its highest number, which results in the smallest possible aperture opening. The camera will shift to a lower shutter speed to account for the smaller aperture.
Freezing action with a fast shutter
If your photo collection is like most, it contains scads of images that were unintentionally blurred because the subject moved too fast for the camera to capture clearly -- and no amount of fiddling in a photo editor can fix them. For future pictures, follow these guidelines to freeze a subject in motion:
- Switch to shutter-priority AE or manual exposure, if available on your camera, so that you can match the shutter speed to the pace of your subject. Until you get a feel for the shutter-to-action relationship, you'll need to experiment to find the right setting. For the subject below, a shutter speed of 1/20 second was much too slow. At 1/125 second, the jumper appears cleanly suspended in mid-jump.
- Don't forget that you must add more light as your raise shutter speed, either by shifting to a larger aperture (lower f-stop number) or by increasing the power of whatever artificial light source you may be using. Otherwise, your image will get progressively darker.
- If your camera doesn't offer manual shutter control or shutter-priority AE, but it does provide aperture-priority AE, you can increase shutter speed by shifting to a lower f-stop. Doing so opens the aperture and lets in more light, which causes the camera to increase shutter speed in response.
- No way to control either aperture or shutter speed? Check to see whether your camera offers a sports or action scene mode. This mode automatically shifts your camera to a higher shutter speed.
Match shutter speed to the pace of your subject.
Here, a shutter speed of 1/125 second froze the jumper cleanly in mid-air in the right photo.
Speeding up your camera's response time
Although many digital cameras offer shutter speeds high enough to capture just about any moving subject, some other camera functions can slow you down.
Try these tricks to kick your camera into a higher gear:
- On most models, you must wait for the camera to write the current image to the memory card before you can take a second picture. Even when this lag time is brief, it can cause you to miss a great shot when you're shooting action. To keep the lag time as short as possible, use the lowest resolution setting that will produce the quality and picture size that you need. The more pixels the camera captures, the longer it takes to write the picture to the camera's memory card.
- Turn off speciality image-processing functions, such as noise reduction and colour effects.
- If you can get by without it, turn off your camera's flash. You can't take a picture during the time it takes the flash to recycle between shots.
- Turn off instant picture review, which displays an image briefly on the camera monitor after each shot. Most cameras prevent you from taking the next shot during the picture review period.
- Make sure that your batteries are fresh. Low-powered batteries can make a camera behave sluggishly.
- When using autofocus and autoexposure, frame the image and set the exposure and focus (by pressing the shutter button halfway down) in advance of the action. That way, you don't have to wait for the autoexposure/focus mechanism to do its thing when the moment you want to capture happens. Just keep the shutter button pressed halfway down and then press it the rest of the way when the action occurs.
If your subject isn't already in the frame at the time, set the focus and exposure by pointing the camera at something that's at the same distance and in similar lighting as your subject will be. - Lastly, you may want to consider switching to movie mode, if your camera offers one. This mode records a brief digital video segment, just like a digital camcorder. You can then pull a single frame from the video clip to use as a still photo. Unfortunately, most cameras limit you to low-resolution images and don't permit the use of flash in this mode. Movie mode also creates large image files, so make sure you have a high-capacity storage card in your camera.
Content adapted from Shoot Like a Pro!: Digital Photography Techniques, McGraw-Hill Publishing, and used with permission: CNET Networks © 2007, and McGraw-Hill © 2007.
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