In photography, showing movement implies some amount of motion blur. Motion blur is caused by the shutter remaining open long enough to allow light from a moving subject to project a part of that motion onto the image sensor. The amount of motion blur is determined by the shutter speed and subject’s rate of movement within the frame.
There are two broad methods of showing movement in photography. In the first, a moving subject’s motion is implied against a static background; this is achieved with a stationary camera that’s firmly held or supported by a tripod. In the second method, you do the opposite of the first; by panning the handheld camera along with the action, your subject remains relatively fixed in the frame against a streaking, motion-blurred background.
Although it’s possible to imply non-panning motion in handheld photography, there’s a practical lower limit to useable shutter speeds, and surpassing it can lead to undesirable camera shake. It’s good practice to use a tripod or to place the camera on a steady surface to ensure that the stationary elements in your composition remain clear when showing motion using relatively slow shutter speeds.
Showing movement with the shutter
While there’s no objective definition of how much motion blur is required before a picture is considered to show movement, it’s safe to assume that a shutter speed that falls just under the threshold necessary to render motion as practically imperceptible is not it. A picture with a nominal amount of motion blur is more likely to be deemed a failed attempt at freezing motion than a successful attempt at showing it. Alternatively, selecting shutter speeds that are too long can negate the appearance of movement and render your subject mostly invisible against the static background.
For specific subjects, setting your shutter speed for a predictable amount of motion blur is straightforward. For example, consider the implied motion of automobile lights streaking along a winding road at twilight. To capture a picture where a single unbroken streak of light spans the entire length of the path, calculate how many seconds it takes several cars, on average, to traverse that distance, and set that as your shutter speed (plus a few seconds for safety). This method works for a variety of subjects whose movements are easy to analyze and predict, such as the rotating blades of windmills, passing trains, and crowds on escalators.
For motion that’s not periodic and easily traceable, experimentation and reviewing your results are the keys to eventual success. Water is a fascinating subject for exposures of all lengths. Short exposures freeze it in place, moderate exposures (up to several seconds) will show its flow, and long exposures render it as something uncanny and dreamlike, like a thick mist enveloping the shore, utterly devoid of apparent movement.
Panning with a moving subject
Panning your camera with a moving subject is a unique way of showing motion while isolating your subject from their surroundings. Panning is achieved by smoothly and accurately moving the camera to follow your subject’s movement, taking care to keep them in a fixed position relative to your frame. When done correctly, your subject is rendered clearly against a streaking background. Unlike showing motion against a stationary background, panning is also a physical skill that requires fluid movement and hand-eye coordination.
A deliberate amount of background motion blur is required to isolate a moving subject successfully. As with everything related to shutter speed and motion, the degree to which the background is blurred by motion depends on the rate of its passage within your frame and the exposure duration.
To become consistently successful at panning with a moving subject requires a mindful approach, lots of practice, and knowledge of several best practices.
- Use the focus point indicators or framing gridlines in your viewfinder as visual points of reference to help you hold your subject steady in the frame.
- Use a lens in the effective focal length range of 100–135 mm to magnify your subject and make them more prominent in the frame
- Endeavour to capture similar subjects at a relatively consistent distance. Doing this will refine your skill.
- If your camera or lens feature some form of optical image stabilization (or vibration reduction), it may be necessary to adjust or disable the setting accordingly, as some stabilizers can inadvertently sabotage quick horizontal panning.
- The depth of field is rarely a factor when panning because subject isolation is achieved by the motion blur of the surroundings and not selective focusing.
- Beware of daytime light intensity, especially in direct sunlight. Panning requires using relatively slow shutter speeds; if taking pictures in shutter priority auto-exposure mode, your camera will adjust the aperture in proportion to your slow shutter speed. Sometimes, the smallest aperture may not be sufficient at preventing overexposure, and you’ll need to increase your shutter speed.