| 摘要 |
PURPOSE:To obtain a telecentric lens of F1.7 for video, by providing the 1st positive lens group for focusing, the 2nd negative lens group for magnification variation, the 3rd negative lens group as a compensator, and the 4th positive lens group, and adding eight numeric limits and compensating aberrations. CONSTITUTION:The 2nd lens group for variable power has a negative meniscus lens 11 and a negative meniscus lens 22 having a convex cemented surface on an object side. The 4th lens group has a lens 41 consisting of a biconvex lens having an intense refracting surface on the object side, negative lens, and positive lens, and a lens 42 consisting of a biconcave lens, biconvex lens having a refracting surface on an image side, and biconvex lens having an intense refracting surface on the object side. The eight numeric limits are added to the optical conditions of the 2nd and the 4th lens groups to compensate the distortion, spherical, and coma aberrations, thus constituting a small-sized lens system having F1.6. |
