Canon’s STM lenses are aimed at videographers. The Stepper Motor (that’s the STM) promises quiet operation while shooting video. But how do the produced noise and the speed compare to Canon’s USM (Ultra Sonic Motor) lenses? That’s what YouTube user marconilanna tries to find out in the video above. In summary: STM lenses are definitely less noisy but a bid slower than the USM lenses. On the other hand being a bit slower allows STM lenses to refocus more smoothly. A Canon EOS 70D was used for the test.