Photographers normally shooting handheld at 1/250 sec can switch on IS to obtain a similarly steady and blur-free result with a shutter speed of just 1/15 second. The inclusion of automatic panning detection makes it easier for photographers to track wildlife and other moving subjects. Photographers can also enable additional noise reduction for shots captured […]
via http://www.creativeportfolio.net/canon-lens-is-lens-for-optical-performance-on-canon-digital-cameras