"By optically distributing power with a gauss type design and two high- refraction glass lenses, flare at maximum aperture is minimized and astigmatism is greatly reduced. Moreover, improvements in the quality of the focused image and the beautiful natural blur of the background are simultaneously achieved. Use of a Micro USM (Micro Ultrasonic Motor) provides fast, silent autofocusing, as well as full-time manual focus. The colour balance is virtually identical to the ISO recommended reference values. Filter size: 58mm Max aperture: f/1.4 With micro USM motor "