| 摘要 |
PURPOSE:To compensate the deterioration of performance of image formation with a parallel plane, by constituting a system comprising a front group having negative refractive index and a rear group having positive refractive index and limiting the refractive index of lenses constituting the front group through the provision of the parallel plane for automatic focusing at the image side of the rear group. CONSTITUTION:A system has a front groupIhaving negative refractive index consisting of a negative meniscus lens L1, a negative lens L2, a positive lens L3 in the order of an object side, and a rear group II consisting of a positive lens L4, a positive meniscus lens L5, a negative lens L6 and a positive lens L7, and a parallel plane III as a photosplitting element is disposed as the back of the rear group II. In zooming, the movement is made while the interval between the front groupIand the rear group II is changed. To compensate the aberration due to the parallel plane III, the equation of 1.7<n2, and 1.65<n1, n2 is satisfied, where refractive index of the lenses L1, L2 and L3 is respectively n1, n2 and n3. Further, the performance can be increased by giving of limit to 8 numerals. |
