Dissecting Canon's STM Lens Stepper Motor

Canon's STM lenses utilize a unique 2-phase bipolar stepper motor with a permanent magnet rotor and a rotationally symmetrical stator, unlike the AFD stepper motor. The article first explains the general working principle of a stepper motor, then delves into the specifics of Canon's STM motor design. The motor uses two independent coils, energized in both directions to create varying magnetic polarities, driving rotor rotation. Full-step and half-step modes are briefly mentioned, but half-step mode isn't explored further due to autofocus systems prioritizing speed over precision.