Canon USM Vietnam
From mechanical motor to USM – Ultrasonic Motor
In the early years of autofocus photography, motors were typically located inside the camera body or attached externally to the lens, transmitting mechanical movement to the focus lens group. In 1987, Canon introduced the EF mount with a fully electronic connection, allowing the AF motor to be miniaturized and placed directly inside the lens. This innovation opened up the possibility of optimizing motors for each lens type, resulting in faster and more precise focusing.
To meet the demands for extremely fast, silent, and powerful autofocus for wide-aperture lenses, Canon developed the ring-type USM (Ultra Sonic Motor). A key feature of USM is the use of ultrasonic vibrations to generate rotational movement that drives the focus group. Ring-type USM is not only powerful but also operates nearly silently — making it ideal for professional lenses.