Patent ID: 8254037

Claim:
A lens barrel comprising: a variable focal length lens system including at least three movable lens groups; and guiding means for moving the variable focal length lens system forward and backward in an optical axis direction, wherein the variable focal length lens system includes at least a first lens group having positive refracting power, a second lens group having negative refracting power, and a third lens group having positive refracting power, arranged in this order from an object side, when a lens position setting is changed from a wide angle end state to a telescopic end state, at least the first and third lens groups are moved toward the object side in such a way that air separation between the first lens group and the second lens group monotonically increases and air separation between the second lens group and the third lens group monotonically decreases, the guiding means includes a fixed frame, a rotating frame to move forward and backward in the optical axis direction relative to the fixed frame while rotating around an optical axis relative to the fixed frame, a rectilinear guiding frame that is disposed in the rotating frame and does not rotate when the rotating frame rotates but moves integrally with the rotating frame in the optical axis direction, a first guide frame to move the first lens group forward and backward in the optical axis direction relative to the rectilinear guiding frame, and a second guide frame to move the third lens group forward and backward in the optical axis direction relative to the rectilinear guiding frame, the second lens group is integrated with the rectilinear guiding frame, and the rectilinear guiding frame is fixed in the optical axis direction when the lens position setting is changed from the wide angle end state to the telescopic end state.