| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a mechanism capable of shortening the length of a cam barrel without reducing an overlapping amount of the cam barrel for light shielding and a moving barrel in the optical axis direction while sufficiently securing a maximum amount of extensions of a first group lens to the cam barrel. <P>SOLUTION: The lens barrel includes: a cam barrel 3 having a first cam groove 3a and a second cam groove 3c on the inner peripheral part; a first group lens barrel 4 that is disposed on the inner peripheral side of the cam barrel 3 with its holding the first group lens 1, engaged with the first cam groove 3a and moves in the optical axis direction along a lift of the first cam groove 3a; and a moving barrel 6 that is disposed on the inner peripheral side of the cam barrel 3 and outer peripheral side of the first group lens barrel 4, engaged with the second cam groove 3c and moves in the optical axis direction along the lift of the second cam groove 3c. When a maximum amount of extension of the moving barrel 6 with respect to the cam barrel 3 is a, a maximum amount of extension of the first group lens 1 with respect to the cam barrel 3 is b, and an overlapping amount of the moving barrel 6 and the cam barrel 3 in the optical axis direction in a state that the moving barrel 6 is moved to the maximum extension position with respect to the cam barrel is c, the lens barrel satisfies the following relational expression: b≥a+c. <P>COPYRIGHT: (C)2013,JPO&INPIT |
