| 摘要 |
A cam mechanism of a photographing lens is provided to maintain a predetermined moving range of a movable optical member by forming a compact cam ring. A cam mechanism of a photographing lens comprises a cam ring(11) having a plurality of cam grooves, a linear moving frame(8) having a plurality of cam followers corresponding to the cam grooves and a zoom lens barrel. The cam grooves having the same basis cam track are disposed in different positions on an optical axis, and has a small length such that the cam grooves are open to a sectional end portion of the cam ring. The cam followers are engaged with the cam grooves and are disposed in different positions on the optical axis. In a front moving end and a rear moving end of the linear moving frame relative to the cam ring, one cam follower is separated from the cam groove and the other cam followers maintain the engagement with the cam groove. When the cam mechanism is housed not to photograph, the linear moving frame is disposed on the optical axis between the front and rear moving ends.
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