Despite the large maximum aperture, the lens remains compact. Lens group 5 moves for rear focusing, and sharp, crisp pictures are obtained at all apertures. The background blur is ideal for portraits. The USM autofocuses the lens quickly and quietly.
Canon EF 100mm f/2 USM Features:
Compact telephoto lens with large maximum aperture
Rear focusing design, and light weight
Sharp, crisp pictures are obtained at all apertures
Fast USM motor for fast and quiet AF