The EF 200-400mm f/4L IS USM Lens with Internal 1.4x Extender from Canon is a high-performance super-telephoto zoom lens with a built-in 1.4x extender that converts the focal range and maximum aperture to 280-560mm f/5.6. The extender is located at the base of the lens and applied with a simple lever switch. An Image Stabilization system offers up to four shutter speed stops of compensation against camera movement, which is ideal in low-light situations and when shooting at its long focal lengths. Three IS modes are available, each optimized for your specific subject. There is a mode ideal for static subjects, one for panning with moving subjects and an Exposure Only mode that applies stabilization only during exposure, offering you the speed you need to follow fast, erratically moving subjects. Fast, quiet Auto Focusing (AF) is provided by a ring-type Ultrasonic Motor (USM), an internal focusing system, dedicated AF algorithms and a high-speed CPU. Full-time manual focus override, which enables the adjustment and fine-tuning of focus even in AF mode, provides precise control over image capture. The Power Focus mode aids focusing during video shooting, allowing the photographer to smoothly adjust focus during filming by twisting the playback ring. Three Focus Limiting Ranges are provided to enable quicker AF in specific situations and AF stop buttons allow you to pause the AF operation if needed. Focus Preset mode allows you to set a focus distance and automatically return to it with just a twist of the playback ring. Focus Preset is available in AF, MF and PF modes.