| 摘要 |
PROBLEM TO BE SOLVED: To provide a lens barrel capable of preventing a movable barrel from tilting with respect to a fixed barrel without increasing the operation torque of a focus ring. SOLUTION: A fixed barrel 1 consists of a rear fixed barrel, an outer fixed barrel 9, and an inner fixed barrel 15. Moreover, a movable barrel 21 consists of a lens holding part 25 for holding the movable side lens group 23 and a cylinder part 27 fitted between the outer fixed barrel 9 and the inner fixed barrel 15. In the inner peripheral surface of the cylinder part of the movable barrel 21, three 1st rectilinear grooves 41 forming a 1st rectilinear groove group and three 2nd rectilinear grooves 43 forming a 2nd rectilinear groove group adjacent to (20 deg. phase difference in this embodiment) these rectilinear grooves 41 are formed at 120 deg.-interval respectively. On the other hand, a 1st rectilinear key group consisting of three 1st rectilinear keys corresponding to the 1st rectilinear grooves 41 and three 2nd rectilinear keys 47 corresponding to the 2nd rectilinear grooves are fastened on the outer peripheral surface of the inner fixed barrel 15 by screws.
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