| 摘要 |
PURPOSE:To reduce the size of a titlted lens system by making it constituted of at least the 1st lens group having positive refracting power, the negative 2nd and the 3rd lens groups, and the positive 4th lens group successively from an object side, fixing the 3rd lens group and moving at least the 2nd, the 1st and the 4th lens groups integrally. CONSTITUTION:Lens groups consists of the 1st lens groupIhaving positive refracting power, the 2nd lens group II having negative refracting power, the 3rd lens group III having negative refracting power, the 4th lens group IV having positive refracting power and the 5th lens group V having positive refracting power, successively from an object side. In the stage of zooming, the 3rd lens group is fixed, and the 2nd lens group II and the 5th lens group V as well as the 1st lens groupIand the 4th lens group IV are moved integrally. The 1st lens group and the 4th lens group as well as the 2nd lens group are moved linearly, and the 5th lens group is moved curvilinearly in order to hold the movement of the image picture caused by the zooming in a fixed position. In the tableIshowing the disposition of paraxial refracting powers, fi denotes the focal length of the i-th lens group, ei the distance between the principal points of the i-th lens group and the i+ lens group, and (f) the focal lengths in the zoom positions at the wide angle end, the intermediate and the telephoto end. |
