| 摘要 |
PROBLEM TO BE SOLVED: To facilitate the manufacture and to lighten the load on a motor. SOLUTION: A cam follower 12a of a cylinder body 12 which holds a lens part 24 engages a cam groove 14a on the internal surface of a moving cam cylinder 14. The cam groove 14a comprises an insert cam that the cam follower 12a engages when the cylinder body 12 is built in the moving cam cylinder 14, a collapsing cam which holds the cylinder body 12 at a collapsing position, an extension cam which moves the cylinder body 12 between the collapsing position and a photography position for photography, and a photography cam which moves the cylinder body 12 for zooming in the photography position. The collapsing cam and photography cam are so shaped as to closely engage the cam follower 12a and the extension cam is so sectioned as to loosely engage the cam follower 12a.
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