| 摘要 |
PROBLEM TO BE SOLVED: To provide a high zoom ratio lens barrel capable of covering up the fluctuation of focus on a variable operation without impairing the operability on the variable operation. SOLUTION: The zoom lens barrel is provided with a rotation cylinder 100 rotated by zooming, a straight cylinder 102 which makes straight advance thereby, a focus cam cylinder A101 which moves a focus lens 2G on each zooming position and permits the focusing operation and a focus coupling ring 103 which rotates the focus cam cylinder A101. With respect to the focus point obtained on a focus cam 101a of the focus cam cylinder A101, a correction amount for correcting the focus point on each zooming position is made to be the sum of corrections by the respective correction cams obtained by a correction cam A104a of the focus cam cylinder A101, a correction cam B102b of the straight cylinder 102 and a correction cam C103a of the focus coupling ring 103. COPYRIGHT: (C)2005,JPO&NCIPI
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