| 摘要 |
PURPOSE:To correct various aberrations, etc. satisfactorily and to make a titled lens high in performance and compact in a zoom lens system consisting of a front group of negative refracting power and a rear group of opsitive refracting power and varying magnifications in accordance with the change in the space between both groups by specifying the foal length and the like. CONSTITUTION:This lens system consists of a front group (II) consisting of a positive lens (L1), a negative meniscus lens (L2), a negative meniscus lens (L3 and a positive meniscus lens (L4) successively from the object side and a rear group (II) consisting of a positive lens (L5) consisting of a positive-negative combined lens, a positive meniscus lens (L6), a netative lens (L7) and a positive lens (L8). The ratio of the combined focal length ofI, II is determined like the equation (1), whereby aberrations are well corrected and the lens is made compact. The ratio between the axial space of the L3 and the L4 and the focal length of the entire system is set like the equation (2), whereby spherical aberrations and curvature of field are improved. Further, the ratio of the radius of curvature at the combined face of the L5 and the focal length the entire system is set like the equation (3), whereby various aberrations by zooming particularly at the wide angle end are corrected. |
