| 摘要 |
PURPOSE:To obtain various aberrations which are satisified excellently and to maintain invariably stable high performance by allowing a lens consisting of three elements in two groups to meet specific requirements. CONSTITUTION:The lens consists of three elements in two groups, i.e. the 1st group G1 of a positive cemented lens of a positive and a negative lens and the 2nd group G2 of a positive meniscus lens having a convex surface on a closer conjugate point successively from a farther conjugate point side. Those lens groups satisfy inequalities I and II, wherein r2 and r3 are radii of curvature of the cemented surface of the 1st group G1 and surface on the closer conjugate point side and r4 and r5 are radii of curvature of surfaces of the 2nd group G2 on the farther and closer conjugate point sides.
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