| 摘要 |
PURPOSE:To effectively solve problems of excessive functions due to disagreement of focal length and inferior focussing accuracy, by shifting a focussing lens in accordance with the focal length of a variable focal point lens and object distance. CONSTITUTION:When the focal length of a variable focal point lens 12 is short, the focussing zone against a photographing distance is adjusted by moving a focussing lens forward or stopping the focussing lens. To a distant object the focussing lens of the lens 12 is pulled back and to a near object the focussing lens is held at a position which moves the lens forward and, therefore, a lens frame 11 is held at a neutral position. When the focal length of the lens 12 is long, the focussing lens is moved forward, stopped, or pulled back. In case where an object is distant, the focussing lens is operated in the same way as in the case of short focal length. Moreover, when an object is at an intermediate distance, the photograph can be taken with the lens at a neutral position. Therefore, no excess and deficiency occur in the focussing ability and the focussing operation can be made with the same accuracy irrespectively of the length of the focal length of the lens 12. |
