The EF 85mm f/1.8 USM Lens from Canon is a highly practical medium telephoto prime lens ideal for a range of applications including portraiture. Its fast f/1.8 maximum aperture is effective in low light and ideal for shallow depth of field focus control. An ultrasonic autofocus motor (USM) provides fast, smooth and quiet AF action and because the front lens group does not rotate during focusing, polarizing and special filter effects can be used effectively.