| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of eccentricity of retaining rings in an approach position and a distancing position in a lens structure having a first lens retaining ring and a second lens retaining ring which function optically in the approach position and the distancing position, respectively. SOLUTION: In the apparatus for preventing eccentricity of the retaining ring for a relative turning lens, at least three positioning recessed parts and follower projections which are engaged with each other in the approach position and the distancing position to define a relative position in an optical axis direction are dispersedly disposed in a circumferential direction on one side and the other side of the facing end surfaces of the first lens retaining ring and the second lens retaining ring. All positioning recessed parts are simultaneously engaged with all follower projections. Therefore, the eccentricity of the first lens retaining ring and the second lens retaining ring is removed.
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