This 16 35mm lens has three types of aspherical elements and uses inner focusing and ring usm for silent and high speed af operation it is also highly resistant to dust and water droplets three types of aspherical elements highly resistant to dust and water droplets inner focusing and ring usm for silent operation drop in gelatin filter holder provided circular diaphragm for better background blur ef mount l series lens aperture range f28 22 ud and three aspherical lens elements ultrason