| 摘要 |
A lens assembly has zooming and focusing capabilities and a plurality of lens groups. The lens assembly has a region ranging from an infinity position to a closest available position and over which some of the lens groups used for focusing purpose are driven in an axial direction parallel to an optical axis of the lens assembly in a distance variable with a change in focal length resulting from a zooming operation. This lens assembly includes a zooming mechanism for driving some of the lens groups used for zooming purpose to respective predetermined positions appropriate to a preselected focal length, a focusing mechanism for driving the lens groups used for focusing purpose independently of the zooming mechanism over a stroke which is constant regardless of the position of focal length selected by the zooming mechanism, and a cam mechanism provided in the zooming mechanism for avoiding any possible interference of any one of the lens groups used for focusing purpose with any one of the remaining lens groups and/or any other stationary member when lens groups used for the focusing purpose are driven over the region.
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