Zoom mechanism for a zoom lens in cameras and the like

摘要

A zoom mechanism comprises a zoom system lens holding frame composed of at least one frame for changing its focal length by moving it in a direction of the optical axis, a focus system lens holding frame which moves together with the zoom system lens holding frame during a zooming operation and is held in the latter so as to be movable in a direction of the optical axis during a focusing operation, a detector for detecting movement of the zoom system lens holding frame from a predetermined reference position, a memory unit for storing a difference in position of the focus system lens holding frame from its normal position in relation to movement of the zoom system lens holding frame from the reference position as an amount of correction and for delivering a stored value corresponding to movement of the zoom system lens holding frame from the reference position a which movement is detected by the detector, and a controller for moving the focus system lens holding frame in relation to the zoom system lens holding frame in relation to the zoom system lens holding frame in a direction of the optical axis by an output of the memory unit.