| 摘要 |
PROBLEM TO BE SOLVED: To obtain a lens barrel constituted so that the positional deviation of lens groups caused by a conventional lens barrel is eliminated and an extremely accurate focusing action can be executed with a simple constitution. SOLUTION: The focusing action of this lens barrel is executed as follows. A gap between a second-group lens holding frame 26 holding a second group lens 15 being the focusing lens group and a third group frame 27 holding a third group lens being the other lens group whose gap exerts the largest effect on an image forming position is detected by a differential transformer 28, and a ring-like focusing cam 9 is driven according to the detection output of the gap between the frames so as to drive the lens 15 to a proper position.
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