Lens Mount & Drive Technology

In-lens Drive Systems

Immediate, accurate response

In 1985, in the midst of the technological trend toward full-fledged autofocusing, most manufacturers of autofocus SLR cameras adopted a body range-finding/body drive system (in which the AF drive motor is built into the camera body with lens drive operated through a mechanical coupler). Canon did not follow this trend, determining instead that the key to domination in the future was to take a bold leap forward, casting off inhibiting technologies and constructing a new system that would eventually surpass other systems. This signaled Canon’s dedication to a new, high-precision AF system that would respond to the photographer’s intentions immediately and accurately.

Aiming to achieve ideal system efficiency, Canon opted for an in-lens motor drive system in which each lens, from fisheye to super telephoto, is powered by the optimum motor. This method provided the answer to Canon’s misgivings about the body rangefinder/body drive system. This system also realizes the basic Canon camera design concept of “locating the ideal actuator in the vicinity of each drive unit and relying on electronic control for all data transmission and drive operations.” Because the actuator is adjacent to the drive unit, energy transfer loss is minimized, boosting efficiency, and noise produced by the drive unit is also reduced. The choice of actuators is expanded as well, making it possible to handle the specific focus torque of each lens and enabling even the largest lens to focus quickly and smoothly. In super telephoto lenses where the drive unit is positioned far from the camera body, this system performs better than a body drive, making it possible to create super telephoto lenses with fast, accurate autofocus. And for professional L-series lenses, the ability of this system to deliver durability and operability in even the most severe conditions is also a significant advantage.