Image stabilization
Reduce the effects of handheld camera shake
It’s hard to believe that a lens with a built-in Image Stabilizer was at one time considered rather a novelty. Now, it’s almost the reverse.
Using an IS lens can help you to achieve sharper images when you’re shooting handheld. It won’t be able to freeze a moving subject, of course – to do that, you’ll need to use a faster shutter speed or a burst of flash – but it will reduce the effect of camera shake.
There are several classes of Canon IS lenses, with some having a simple on/off switch and others having an additional switch for setting the IS mode. Mode 1 is the all-purpose setting that stabilizes both horizontal and vertical movement, while Mode 2 compensates for movement in just one plane – and is the one to choose if you’re panning the camera to track a moving object. A few lenses have a Mode 3 option, which will only activate the IS when an image is taken and can produce a more natural looking image in the viewfinder when photographing action.
The performance of IS units varies as well. The EF 24-105mm f/3.5-5.6 IS STM has a four-stop Image Stabilizer, for instance, while the RF 24-105mm F4-7.1 IS STM’S gives up to five-stops of shake reduction, allowing you to use a shutter speed that’s five stops slower than you would normally have to use in order to get a sharp image.
Each ‘stop’ is equivalent to a shutter speed that’s twice as slow. So if you can normally achieve a sharp shot with an 80mm lens handheld at 1/80 sec, you could potentially get the same sharpness at 1/40 sec with one stop of stabilization, 1/20 sec with two stops, and so on. Technique still plays a huge part in getting the sharpest results though.