| 摘要 |
PURPOSE:To provide a cam ring for a zoom lens which is inexpensive and is deformation-free by forming cam grooves on the inside of one halved cylinder of a plastic hollow cylinder consisting of a pair of halved cylinders without penetrating through the same. CONSTITUTION:Cam grooves 5, 6 are formed on the inside of one halved cylinder 4 of a plastic hollow cylinder consisting of a pair of halved cylinders 4 and 7 without penetrating through the same, whereby an intended cam ring for a zoom lens is obtained. Since the cam grooves 5, 6 are not penetrated in the cam ring obtained in such a way, the change in the groove width after formation of the grooves 5, 6 is obviated and since said ring is made of a plastic, the ring is produced inexpensively. |
