| 摘要 |
PURPOSE:To achieve focusing succeeding to zooming in a zoom lens possible for macrophotographing by transferring said lens to a macro region by turning an operating knob of a zoom ring. CONSTITUTION:A fixed lens system 4 is provided at the rear end of a fixed barrel 1, a holding barrel 3 holding a focus lens system 2 is at the front end, the 1st cam barrel 5 is at the center recess and the 2nd cam barrel 6 is at the external circumference. The 1st and 2nd cam barrels are rotated incorporately with a pin 5a and a groove 6a, and the 2nd cam barrel only is slidable toward the light axis. Through the turning of both cam barrles, zoom systems 9, 10 make zooming back and forth. When a knob 7 on the 2nd cam barrel turns, the 2nd cam barrel is shifted axially by the operation of a deflection cam 7c with the lens 10, allowing to make easy for the focusing succeeding to zooming. |
