| 摘要 |
PURPOSE:To enable the lens to be driven with relatively light load by performing manual focus controlling with high accuracy by way of a helicoid mechanism and automatic focus controlling without the aid of the helicoid mechanism. CONSTITUTION:There are an outside helicoid barrel 13, middle helicoid barrel 15 and inside helicoid barrel 17. The barrel 15 and distance setting ring 11 are coupled and the cam face and concave face with which a set distance detecting member 31 and automatic focus detecting member 33 make contact are provided to the rear end face of the ring 11. The barrel 13 is secured to a stationary ring 21 and a rectilinear propagation key 19 is secured to the barrel 17. When a manual-automatic focus setting changeover ring 26 is set to manual, a lens driving second moving member 23 makes sleeve fitting to the first moving member 17 connected by way of a helicoid mechanism, whereby both are integrally moved. When it is set to automatic, the second moving member 23 display relatively with the first moving member 17 to drive the lens, whereby the focus controlling is accomplished. |
