What is Image Stabilization?



Image Stabilization, or simply ‘IS’, is a technology employed in some Canon SLR lenses and point-and-shoot cameras that compensates for camera shake. This allows for sharp photos at shutter speeds that would normally be slow enough to allow camera shake to affect the final image.

Other manufacturers have this feature in their products as well, though it goes by other names. In the Nikon system the same feature is called Vibration Reduction, or ‘VR’. For the remainder of this article however, all stabilization will simply be referred to as IS.

While Canon and Nikon use in-lens IS for their SLR systems, and in-body IS for their compact cameras, other manufacturers (e.g. Sony) use in-body IS for both.

IS works by moving either an element inside the lens (for in-lens IS), or the sensor itself inside the camera (for in-body IS) in response to movements of the camera. Most importantly this compensates for the natural vibrations that occur whenever someone holds a camera without using a tripod or other support.

As a rule of thumb, a shutter speed of slower than 1 over the focal length (for example, less than 1/200 for a 200mm focal length) will mean that the photo is likely to be spoiled by camera shake-induced blur. Most manufacturers claim that their stabilization system allows for an additional 2 to 4 stop of ‘handholdability’, which would mean that a 200mm lens could be safely handheld at shutter speeds of 1/50 or even 1/10.

IS is unquestionably a very useful feature of cameras and lenses. In allowing sharp photos at slower shutter speeds than would otherwise be possible, it delays the point at which a tripod or flash would be required, opening up a world of low-light photography that was previously impossible. Aside from camera shake caused by human hands, IS can also compensate for the vibrations caused by a vehicle with its engine running, for example a car, truck or even a helicopter – another useful application.

Because point-and-shoot cameras produce much worse results at high ISOs than DSLR cameras, and because they typically can’t be used with off-camera flashes, IS is arguably even more of a boon to point-and-shoot cameras than it is to SLR systems. It has become almost an essential feature.