| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize a lens barrel itself and also to precisely regulate the maximum aperture size of a shutter blade. SOLUTION: A driving barrel is rotated at the time of varying power, and a moving barrel having a front group lens and a shutter block 22 is moved in the direction of an optical axis by rotation at a zoom lens barrel. A straight advancing guide barrel stopping the rotation of the moving barrel is freely turnably supported at the inside of the driving barrel, and also a cam barrel 18 is freely turnably supported at the inside of the straight advancing guide barrel. The cam barrel 18 is rotated by transmitting the rotation of the driving barrel, so that a rear group lens frame which it has at inside is moved in the direction of the optical axis by an action with the straight advancing guide barrel. The moving barrel is moved between a position at which the shutter block 22 enters the inner surface of the cam barrel and at the position at which it escapes from it at the time of varying the power. The shutter block 22 is provided with a projected member 75 varying the regulating position of the maximum aperture sizes of the shutter blades 56 and 57. A cam 72 engaged with the projecting member 75 when the shutter block 22 enters and regulating the maximum aperture sizes of the shutter blades 56 and 57 in accordance with the focal distance of a photographing lens is formed on the inner surface of the cam barrel 18 so as to be inclined in a rotating direction centering the optical axis.
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