• SSM (Super Sonic wave Motor) is designed for fast, smooth, silent automatic focusing. This technology achieves high torque at low speed with rapid start/stop response. It operates through the ability of a piezoelectric device to reshape itself quickly when voltage is applied. • Two aspherical and two ED lens elements correct visual aberrations and improve picture quality across the entire zoom range. • The Auto Clutch mechanism stops the manual focus ring from rotating while in AF mode.