Canon developed a 21-zone metering sensor to accommodate 45-point area AF. Using a newly developed algorithm, this metering system performs high-speed calculations of output from 21 zone sensors and AF information, and adjusts exposure instantly.

This configuration enables the camera to make compensations appropriate to shooting conditions and maintain exposure stability. The system also incorporates an average metering element that factors in periphery conditions, providing accurate exposure even when the composition changes slightly, or when the subject covers multiple metering points.