| 摘要 |
PURPOSE:To simplify the structure of a zoom lens which performs the closeup shooting with extension of the whole lens body, by deforming the cam and key grooves of a cam barrel and at the same time providing an interlocking mechanism between a control ring and the cam barrel. CONSTITUTION:For the normal shooting, a control ring 6 is turned toward its circumference. As a result, a lens support barrel 5 is turned toward its circumference and at the same time shifted toward the optical axis of the lens to perform focusing. When the ring 6 is moved toward the optical axis, a cam barrel 3 is turned in its circumference direction to perform zooming. In the case of the close-up shooting, the ring 6 is shifted toward an arrow A. Thus the barrel 3 is turned slightly toward an arrow B. Then the ring 6 is further shifted in the direction opposite to the arrow A, and a barrel 4, the barrel 3 and lens frames 8 and 9 are all shifted in a body. |
