The way that movement is captured in a photograph is governed by the shutter speed that’s used. A fast shutter speed, or short exposure time, freezes movement whereas a slow shutter speed or long exposure time results in motion blur.
The trick to freezing movement is to know how fast the shutter speed needs to be to suspend the subject's motion. When shooting motion as a blur, however, you need to consider how much movement you want to capture. The longer the exposure time, the greater the blur - or at least up to a point. If you have an extremely long exposure, say of 30 seconds and a relatively fast-moving subject, for example, a person walking across a landscape, they may not be in any one place long enough to register in the image.
Let’s take a look at how to get the result you want.
Shutter priority mode is the easiest exposure mode to use for shooting movement as a blur. It lets you set the shutter speed while the camera takes care of the aperture.
As previously mentioned, you need to think about how fast your subject is moving when you’re deciding the shutter speed. With fast action like cyclists or runners, for example, a shutter speed of 1/125 sec or 1/60 sec is enough to render the idle areas, like the body and head, relatively sharp while their feet and legs are blurred, giving a sense of the action and energy.
If you pan with a fast-moving subject, with practice, you’ll be able to drop the shutter speed further perhaps to 1/30sec or 1/15sec and create a nicely blurred background while parts of the subject are in focus. Again this conveys a sense of speed. The trick is to pan smoothly with the subject while using the focus point visible through the viewfinder as a crosshair to track your subject.
> For more on the panning and tracking technique see our video guide.
Shooting landscapes and seascapes
We tend to think of landscapes as being motionless but crops and trees can sway in a breeze, rivers flow downhill and clouds drift across the sky. All of these can be recorded with blur to create more interesting images than the traditional still shot.
Clouds don’t usually move very fast so you need a long exposure to record them with blur, often 30 seconds or more. This length of exposure is not achievable when you’re shooting in daylight unless you have a neutral density filter on the end of your lens.
Similarly, turning choppy water into a smooth mist requires exposure of a couple of minutes or so, making a dense ND filter like a Lee Filters Little Stopper or Big Stopper essential.
Naturally, you need to support the camera on a good solid tripod to make sure that all the motionless elements in the scene are recorded in pin-sharp detail.
Exposures longer than 30 seconds usually require you to shoot in Bulb mode and use a remote release to avoid making the camera wobble while the shutter is open.