Power zoom lens and camera system

摘要

A power zoom lens having a zooming lens unit which is movable in an optical axis direction to vary a focal length thereof and which is detachably mounted to a camera body. The power zoom lens includes a drive mechanism for driving the zooming lens unit, a detecting device for detecting a focal length of the power zoom lens, a memory device for storing the focal length detected by the detecting device, and a control device for controlling the drive mechanism until the focal length stored in the memory device is obtained.