| 摘要 |
PROBLEM TO BE SOLVED: To provide a multistage zoom lens barrel whose diameter is made smaller even when a guiding groove must be formed in a helicoid part. SOLUTION: This zoom lens barrel is constituted as the multistage type one by combining plural barrel members, and at least a pair of adjacent barrel members is connected by helicoid-coupling an outer peripheral surface helicoid part formed on the outer peripheral surface of either barrel member with an inner peripheral surface helicoid part formed on the inner peripheral surface of the other barrel member. The inner peripheral surface helicoid part is provided all over the periphery of the inner peripheral surface and respective helicoid ridges 315 constituting the inner peripheral surface helicoid part are equipped with a 1st high ridge part 315a and a 2nd low ridge part 315b and continuously formed. The 2nd ridge part 315b regulates the guiding groove for guiding the advance and retreat movement of the other barrel member in an optical axis direction. A notch 315c for making pulling stroke in the perpendicular direction of a forming die member for the barrel member small is formed on the 1st ridge part 315a.
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