| 摘要 |
A varifocal lens barrel includes movable lens groups including a focusing lens group which is moved by different amounts of movement at different focal lengths, a focus operation ring, a focus lens frame which supports the focusing lens group, a guide ring positioned around the focus lens frame, a bottomed focusing cam groove formed on the focus lens frame or the guide ring, a spherical follower which is supported by the focus lens frame or the guide ring, a biasing member for pressing the spherical follower against the bottomed focusing cam groove, and an adjustment mechanism which varies a relative moving range of the spherical follower in the bottomed focusing cam groove in accordance with a variation of the focal length to vary an amount of movement of the focusing lens group per unit of rotation of the focus operation ring.
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