| 摘要 |
PURPOSE:To photograph a document, especially, an original of about A4 size on a sheet film or the like by arranging the first-fourth lenses in order from the object side to the image side. CONSTITUTION:The first lens 10, the second lens 12, the third lens 14, and the fourth lens 16 are meniscus lenses, and lenses 10 and 16 are convex meniscus lenses and are so arranged that the convex face of the lens 10 is directed to the object side and that of the lens 16 is directed to the image side, that is, the concave face of the lens 16 is directed to the object side. Lenses 12 and 14 are concave meniscus lenses and are so arranged that the convex face of the lens 12 and the concave face of the lens 14 are directed to the object side. When the resultant focal length of the whole of the system, the radius of curvature of the i-th lens face from the object side, the distance between lens faces, the refractive index of the i-th lens, and the Abbe's number of the i-th lens are denotes as (f), ri (i=1-8), di (i=1-7), ni (i=1-4), and vi (i=1-4) respectively, they satisfy numerical values of a list.
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