The EF 400mm f/4 DO IS USM Lens from Canon utilizes multi-layer diffractive optical (DO) lens technology to correct chromatic aberrations, substantially reduce lens size and provide excellent overall telephoto image quality. This offers an alternative for sports, nature and wildlife photographers, giving exemplary results in a size previously unheard of for a lens of such a focal length and aperture. In addition, Image Stabilization provides up to 2-stops of correction against camera shake for less blur when using slower shutter speeds. Furthermore, with two distinct stabilization modes are featured. Mode 1 is best used with still subjects while Mode 2 is optimized for panning with moving subjects. An ultrasonic autofocus motor (USM) enables fast, smooth and quiet AF action and the AF stop buttons allow you to temporarily pause autofocus. Also, to minimize autofocus time with specific subjects, a focusing range limiter function lets you set the distances at which the lens will focus
