Camera Shake.

When you take a photograph you capture a moment in time. The faster the shutter speed is the shorter the moment will be. If you use a fast enough shutter speed the moment will appear frozen and without movement. When you are choosing a shutter speed you will have to take into account two separate types of movement:

• subject movement. This is anything within the picture area that is moving or may move during exposure.
• camera movement or 'camera shake'. This is movement of the camera during exposure.

Movement appears as blurring of the image. Subject movement will only affect the part or parts that actually move during exposure while camera shake will affect the whole image to the same degree.
Before we look at how to choose shutter speeds we will address what is a common cause of ruined photographs.
Camera Shake.
Unlike subject movement which is relative to the camera, and you can often see it, camera shake is movement of the camera relative to the subject and, as it happens during exposure, you cannot see it. Everyone suffers from camera shake at some time or other.
Most instances of camera shake occur during hand held photography. This, as you have probably noticed, is a very popular way to take photographs so it is wise to know when you are likely to fall victim to camera shake. Like using a fast enough shutter speed to freeze movement in a photograph you must also use a fast enough shutter speed to freeze any movement of the camera. The actual shutter speed you use to combat camera shake is generally determined by a couple of factors.

Minimum recommended shutter speeds for hand held photography.
24mm	1/30th
28mm	1/30th
50mm	1/60th
70mm	1/60th
90mm	1/125th
135mm	1/125th
200mm	1/250th
300mm	1/250th
500mm	1/500th

• an individuals ability to hold a camera steady.
• the focal length of the lens in use at the time.
• magnification. If you are shooting close-ups camera movement is magnified along with your subject.

Many people over estimate how steady they can hold a camera but minimum shutter speeds for your average Joe Punter hand holding a camera are usually given as the inverse of the focal length in use. The word 'inverse' comes from the world of mathematics and as such is a bit scary to a lot of people but in this case it just means 'one over'. As in 'one over the focal length'. Here is a wee example of how easy it really is.
Using a standard 50mm lens the minimum shutter speed you should use will be 'one over 50', which is 1/50. To turn it into a shutter speed you simply call it a fraction of a second, like this; 1/50th of a second. The nearest shutter speed you can set is actually 1/60th of a second but you get the idea.
Or.
Using a 200mm lens the minimum shutter speed you should use will be 'one over 200', which is 1/200th of a second. So you would set your shutter speed to 1/250th of a second, that being the closest to 1/200.

These figures are just a rough guide and may vary according to individual ability. Over time you will learn how slow a shutter speed you can hand hold but if in doubt always err on the fast side. It would be unwise to hand hold any camera/lens combination below 1/30th of a second.

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