| 摘要 |
PURPOSE:To obtain a compact lens system having high performance and aberration corrected in a well-balanced state by allowing a lens system having quadruple structure consisting of a positive meniscus lens, a negative lens, a positive lens, and a negative meniscus lens in order from the object side to satisfy prescribed conditions. CONSTITUTION:A lens system having quadruple structure consisting of the 1st lens whose convex surface faces the object side, the 2nd lens, the 3rd biconvex lens, and the 4th lens whose concave surface faces the object side is allowed to satisfy conditions represented by inequalities I -VI. In the inequalities n2, n3 and n4 are the refractive indexes of the 2nd, the 3rd and the 4th lenses to a line (d), respectively; nu1 is the Abbe's number of the 1st lens; f is the focal length of the whole system; f4 is the focal length of the 4th lens; and f123 is the synthetic focal length of the 1st, the 2nd and the 3rd lenses. |
