The EF 20mm f/2.8 USM Lens from Canon is an ultra-wide-angle lens with a fast maximum aperture for full frame EF mount cameras. A floating rear focusing system gives nice images at all subject distances and an ultrasonic motor (USM) enables fast, smooth and quiet autofocus. Full-time manual focus override allows for precise manual focus even when in AF mode. The minimum focus distance is 9.8".