How long will your camera’s shutter last
The shutter speed is controlled using the camera’s shutter, a precision-engineered mechanical device found just in front of the image sensor in your DSLR. The skill of its design lies in being to regulate the shutter opening precisely – particularly at the fastest shutter speeds.
The stresses of this high-speed firing and re-arming procedure mean that top-end models are normally launched with an indication of how long the shutter will last until it needs to be replaced. For example, many pro-level models are good for 300,000 cycles.
Entry-level DSLR models are not given a figure, but are understood to be good for 50,000 shots. Programs are available to check the on-board counter of your DSLR to see how many times your shutter has been fired.
Understanding shutter speed and camera shake
Like the aperture, the shutter speed is not just a way of adjusting the overall exposure of an image. It also has artistic uses, controlling the amount of blur (or lack of it) in a picture.
This effect is only noticeable if either the camera or the subject is moving. Even with stationery subjects, shutter speed is crucial if the camera is handheld – the slightest movement of your body results in ‘camera shake’ and a blurred image. If the shutter speed is fast enough, this movement becomes imperceptible.
Just how fast the shutter needs to be to avoid camera shake depends on a number of factors (including whether you use an image-stabilised lens, and how windy it is). The most important factor is the focal length of lens.
The more you zoom in (and the narrower the angle of view) the more this camera shake becomes noticeable. So the longer the focal length you use, the faster the shutter speed you need.
A rough-and-ready rule is that your minimum shutter speed should be ‘one over’ the focal length. So with a 50mm lens setting use 1/50 sec or faster, and 1/200 sec or faster with a 200mm lens.
Use a solid tripod, though, and the camera shake problem is eliminated, giving you complete control of shutter speed – and therefore also a greater choice of aperture.
Moving subjects will also affect shutter speed choice. If you want the subject to appear sharp in the shot, a fast enough (short enough) speed must be used to make the subject appear still.
Choosing the exact speed depends not just on the speed of the subject, but also on how big it appears in the frame, and its direction. You need a faster shutter speed if the subject is moving directly across the field of vision, rather towards the camera – and a faster speed the bigger the subject appears in the picture.
However, it is not essential for everything to be completely still – many moving subjects are more artistically captured with a deliberately long shutter speed.
The secret is to use a shutter speed that is long enough to make the blur look deliberate, rather than accidental. Using a tripod helps – so static parts of the scene appear sharp, and only moving parts appear artistically blurred.
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