As a general rule of thumb, you can safely shoot hand-held at a shutter speed equivalent to the reciprocal of the focal length you are using, without suffering camera shake. For example if youâ€™re using a 100mm focal length (a typical 3x zoom compact at full telephoto is equivalent to 105mm) then you can take a sharp hand-held shot at a shutter speed 1/100th of a second or faster. If youâ€™re using a 35mm focal length then 1/35th of a second is safe, and so on.
This example shot was taken hand-held on my Sony A100 SLR at a focal length of 50mm and a shutter speed of 1/50th of a second. As you can see itâ€™s sharp and shake free.
If I try to take the shot again with the same focal length but a shutter speed of 1/10th of a second, itâ€™s impossible to hold the camera steady enough for a shake-free shot. As you can see, the result is badly blurred.
Some recent cameras include technology which can help reduce the effects of camera shake at low shutter speeds. Some cheaper systems use electronic processing to counteract movement, a system often used in digital video cameras. Some manufacturers, such as Canon and Panasonic, use moving optical elements within the cameraâ€™s lens to cancel out camera vibration. Others, including Pentax, Sony and newer Ricoh models use a system which moves the cameraâ€™s sensor to achieve the same effect.
Electronic systems can reduce picture size and quality and are not as effective as the latter two methods. While there is no clear advantage in performance between moving-lens and moving-sensor systems, the latter has the advantage for SLR users that the lenses are cheaper to buy, since the anti-shake system is built into the camera body.
The Sony A100 has a moving-sensor anti-shake system that provides around 3.5 stops of extra stability. This next shot was taken with a focal length of 50mm at 1/10th of a second, but this time the anti-shake system is switched on. It has detected the vibration and corrected it by moving the sensor to compensate, resulting in a much sharper shot.