Avoiding The ShAkeS

there’S More to selecting a shutter speed than simply controlling exposure. Very fast – or short, if you prefer – shutter speeds have the effect of freezing movement because the exposure time is so brief. With slower speeds, there’s time for the subject to move during the exposure, which creates blur in the image. This is blurring that you might actually want, but using slower shutter speeds can also result in blur that you don’t want… caused by camera shake. You might think you have a steady hand, but magnifying the image will reveal you haven’t, and that’s another image heading for the ‘Delete’ button.

Camera shake is a bigger problem with telephoto lenses, which have a higher magnifying power and thus also magnify even the tiniest of hand movements, but at some point it will be an issue regardless of the lens focal length. You need to think about this when working out what shutter speed to use.

There’s a simple rule for determining when camera shake becomes a real risk and you should put the camera on a tripod. This rule states that the slowest ‘safe’ shutter speed for hand-held shooting can be determined by converting the lens’s focal length into a shutter speed… i.e. if you’re using a 300mm telephoto lens, then the slowest shutter speed to avoid camera shake is 1/300 second. (If shooting with an ‘APS-C’ or Micro Four Thirds format camera, use the 35mm-equivalent focal length with this rule.)

What about image stabilisation? It’s now available in most digital cameras and/or accessory lenses (or both in some systems) and it will certainly allow you to shoot at a slower shutter speed than would normally be the case, but there is still a limit. If you want to experiment with blurring subject movement, you’ll need to use a tripod. Likewise when shooting at night and if you want to keep using low sensitivity (ISO) settings to avoid unwanted noise in the image.