Canon Lens Label Interpretation

AFD：Arc-Form DriveArc DC motor is developed for AF drive of early EF lens. Unlike the USM motor, the AFD motor focus has sound. DO: Multi-Layer Diffractive Optical ElementCanon announced on September 4, 2000 that it had successfully developed the world's first "multilayer diffractive optical element" for use in a camera lens. The multi-layer diffractive optical lens...