We’re rather spoilt in today’s 21st Century digital world. When I were a lad – oh dear, have I reached that stage already? – if you made a photographic mistake you wouldn’t know about until after the film was processed. This could be weeks afterwards, long after the time when the mistake could be easily rectified. Now of course, thanks to LCD screens and the like, you can see immediately when a shot hasn’t worked and so do something about it straight away.
One common ‘mistake’ is camera shake. This is when a photo is slightly soft, not because of a focusing error but due to the camera moving slightly during an exposure. This is more likely to happen when a camera is handheld, but it can still occur when a camera is mounted on a tripod, particularly if it’s windy or the ground is soft and squidgy.
The likelihood of camera shake increases the slower the shutter speed either you or the camera selects. (In automatic camera modes, including Program, cameras typically bias exposure to a relatively fast shutter speed to reduce the risk of camera shake. That doesn’t mean that camera shake won’t occur though.) Camera shake is also more likely the longer the focal length lens used. Longer lenses magnify any movement you make during the exposure, increasing the effect of camera shake. Fortunately, as we’ll see in a moment, there is technology that will help you avoid the shakes.
First though, let’s go old school. There’s a very rough-and-ready rule that you can use to reduce the risk of camera shake: select a shutter speed value that’s approximately the same value as the focal length of the lens. (When shooting with a full-frame camera.) So, for example, if you’re using a 200mm lens try to use a shutter speed of at least 1/200; faster still if you know that you’re prone to the shakes, if you’re shooting in high wind, or you’re standing in an awkward unsteady position. If you’re shooting with an APS-C or M4/3 camera you have to modify the rule a bit: multiply the focal length by 1.5 for an APS-C camera, or double it for a M4/3 camera, to get the desired shutter speed.
The technological solution mentioned above is image stabilisation. This comes in two forms: lens IS (VR, OSS, or OIS) or sensor IS. With lens IS optical elements within the lens are subtly shifted in order to compensate for any slight movement you might make; with sensor IS it’s the sensor itself that’s shifted (though some cameras combine lens IS and sensor IS if both are available). Typically image stabilisation can let you shoot at a three to five-stop slower shutter speed than the rule above would suggest. IS kicks in when you press the shutter button down to the halfway point (when metering and focusing are also activated). The key is let IS work its magic before pressing the shutter button fully. This can take a second or two, but once it’s working you should see the image in the viewfinder look more, well… stable.
You’re more likely to need a slow shutter speed when light levels are low. You can delay the need for slower shutter speeds either by raising the ISO or by using a larger aperture. The downsides to raising the ISO is an increase in the amount of visible noise. (Though modern sensor are ridiculously good at suppressing noise at all but the highest ISO settings). Using a larger aperture means dealing with reduced depth of field and – depending on the lens – the likelihood of more chromatic aberration and vignetting.
If you really need to use a slowish shutter, don’t have IS or lack a tripod then keeping the camera as steady as possible is the only solution. Ideally don’t hold the camera at arms’ length but use the viewfinder instead, with the camera pressed lightly against your face. (Admittedly this is a bit trickier if your camera doesn’t have a viewfinder…)
Then, you need to stand (or kneel) as upright as possible, keeping your feet shoulder-width apart with your elbows tucked against your body. Grip the camera gently but firmly with your right hand and use your left hand to support the lens if possible. Breathe in and then slowly out. Then, just before you breathe in again, gently squeeze the camera shutter button down to take the shot.
All that’s left then is to review the shot, zooming in to check sharpness. Of course, when I were a lad (here we go again) we just had to make do with bringing the print closer to our face… Ah, the good old days!