Ultrasonic motor drive Canon EF lens mount

ultrasonic logo

ultrasonic motor (usm) lenses appeared introduction of ef 300 mm f/2.8l usm lens in 1987. canon first camera maker commercialise usm technology. ef lenses equipped usm drives have fast, silent , precise autofocus operations, , consume less power compared other af drive motors.

there 3 types of usms: ring-type usm, micromotor usm, , nano usm. ring-type usm allows full-time manual focus (ft-m) operations without switching out of af mode. micromotor usm used bring down cost of lens. possible implement ft-m micromotor usm; however, requires additional mechanical components, , vast majority of micro-usm lenses not offer such capability. nano usm introduced in 2016 release of canon s latest iteration of ef-s 18–135mm lens. intended offer af speed of ring-type usm quietness of stm mechanisms (see below).

some older usm lenses identified gold ring , word ultrasonic printed in gold on lens barrel. l lenses usm don t have gold ring, still have word ultrasonic printed on lens barrel.