| 摘要 |
A lens barrel is mated with a lens mount through use of a screw thread whereby relative rotation adjusts lens focus. The lens barrel and lens mount are additionally provided with an interengaging formation that is interposed between an optical axis of the lens barrel and the screw thread. This formation provides a cylindrical sliding contact which isolates any particles produced by operation of the screw thread from reaching the optical components at or near the optical axis.
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