The SLR Hut EF 500mm f/4L IS II USM Lens from Canon has every upgrade necessary to make it the ideal telephoto lens for professional-grade photography. Three-mode optical image stabilization allows shooting at shutter speeds 4 stops slower, and the advanced third IS mode activates only when shutter button is fully pressed, so that fast-moving subjects pan without the IS function interfering with composition and framing. Ultrasonic Autofocus Motor (USM) enables smooth, fast, quiet autofocus and Power Focus mode allows smooth focus change, especially important while shooting video. The AF stop button pauses autofocus with just a touch, and manual focus override gives precise manual focus in AF mode.