Canon's latest optical Image Stabilizer (IS) technology provides up to 4-stop compensation for image blur caused by camera shake and slow shutter speeds. 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. To ensure consistently accurate results at all zoom positions, the IS system within each lens has been optimised for that lens' specific focal length range. Since the IS system is based within the lens, the results are visible through the viewfinder when framing the image.