| 摘要 |
PURPOSE:To make a high variable magnification zoom lens system including a wide angle region high in performance and compact by performing zooming by four elements of positive refracting power precedence type, and further moving the 4th lens group which moves during zooming. CONSTITUTION:The lens system is constituted of the 1st group I of positive refracting power, the 2nd group II of negative refracting power, and the 3rd group III and the 4th group IV of positive refracting power which are movable in the optical axis direction, successively from object side. Zooming of high variable magnifications including a wide angle region is accomplished by cooperatively moving these lens groups I-IV in the optical axis direction. Focusing is accomplished by further moving the 4th group IV which moves during the zooming. The focal length f1 of each group and the longest focal length fL of the entire system are set in the relations of the equations (1)-(3), whereby the degradation in aberrations is prevented and the lens system is made compact. |
