| 摘要 |
PURPOSE:To position a main lens system correctly, by providing a cam mechanism which sets the second auxiliary lens frame to the rear of a main lens frame when the main lens frame is moved backward to a prescribed magnification position. CONSTITUTION:An auxiliary lens frame 13 for reduction is attached to the rear end of a main lens system 4 freely rotatably by a shaft 14. This auxiliary lens frame 13 for reduction holds an auxiliary lens system 15 and is provided with a pin 16 in the side part. When the main lens frame 4 is moved backward toward a reduction position, the auxiliary lens frame 13 for reduction receives the tension of a spring 10 to stand up gradually and is set to the rear of the main lens frame 4. This standing-up of the auxiliary lens frame 13 for reduction is controlled by the pin 16 and a cam groove 11b, and thus the main lens frame is positioned correctly in a prescribed magnification position. |
