| 摘要 |
PROBLEM TO BE SOLVED: To secure incidence of a sufficient light amount to a photographing optical system, with excellent position accuracy of a first lens group secured and to downsize a lens barrel and an imaging device.SOLUTION: A cam ring and a first group holding frame have a cam follower provided on one part, and have a cam groove with which the cam follower is slidably engaged formed on the other part, and by a rotation of the cam ring to a direction around an optical axis, the cam ring and the first group holding frame are moved to the optical axis direction or rotated to the direction around the optical axis. By the movement of the first group holding frame to the optical axis direction or the rotation thereof to the direction around the optical axis, a barrier support frame is moved to the optical axis direction, and in a photographing state, the first group holding frame is supported by a rectilinear advancement ring unrotatably to the direction around the optical axis and movably to the optical axis direction. In one section between a collapsed state and the photographing state, the first group holding frame is supported by the rectilinear advancement ring rotatably to the direction around the optical axis, and in a process from the collapsed state to the photographing state, in one section, the first group holding frame is rotated to the direction around the optical axis with respect to the rectilinear advancement ring by the rotation of the cam ring, thereby the first group holing frame and the barrier support frame are relatively moved so as to get closer to each other in the optical axis direction. |
