| 摘要 |
PURPOSE:To obtain a lens for a small-sized image pickup apparatus which is small in size, is bright, can be mounted to the same mount as that of the conventional image pickup tube and permits the use of a unit diaphragm by forming the lens consistion of the five groups and five elements satisfying the specific conditions. CONSTITUTION:This lens is constituted, successively from the object side, of the 1st lens which is a negative meniscus lens with the convex face directed to the object side, the 2nd lens which is a biconvex lens where the face having strong curvature is preferably on the object side, the 3rd lens which is a biconcave lens, the 4th lens which is a convex lens and the 5th lens which is a convex lens. The conditions (1)-(5) are satisfied when codes are designated as follows: (f) the focal length of the entire system of the lens, di; the wall thickness or air space of the i-th lens, fi; the focal length of the 1st lens, f1,2; the combined focal length from the 1st lens to the 2nd lens, ri; the radius of curvature of the i-th face. |
