When to use IS

What is image stabilisation and can I use it to freeze moving subjects?
Chandrakant Patel, Vadodara

Image stabilisation (IS) is a technology that helps minimise any blur used due to camera shake. It basically allows you to use shutterspeeds slower than usual and still obtain sharp results. To understand this, we need to remember that for any given focal length, it is advisable to use a shutterspeed that is a reciprocal of the focal length. For example, for a 100mm lens, you should use a minimum shutterspeed of 1/100sec. Now, stabilisation lets you shoot at shutterspeeds that are three or four stops slower. So, you may be able to shoot at 1/6sec while using a 100mm lens. Do remember that IS is only useful for reducing the effect of camera shake. It does not prevent motion blur and hence, does not help while shooting moving subjects.