| 摘要 |
PROBLEM TO BE SOLVED: To provide a lens for reading an image which is composed of six lenses, namely, positive, positive, negative, negative, positive and positive in this order from an object side, which is comparatively bright, whose angle is wide and whose chromatic aberration is excellently corrected. SOLUTION: A 1st positive lens L1 whose convex surface faces the object side, a 2nd positive lens L2 whose convex surface faces the object side, a 3rd negative lens L3 whose concave surface faces an image side, a 4th negative lens L4 whose concave surface faces the object side, a 5th positive lens L5 whose convex surface faces the image side and a 6th positive lens L6 whose convex surface faces the image side are disposed in this order from the object side. Besides, a diaphragm 2 is disposed between the lenses L3 and L4. At least the lenses L2 and L3 or the lenses L4 and L5 are mutually joined. Besides, the lenses are constituted so as to satisfy following conditional expressions (1) and (2). (1) 80×(θ+-1)+νd+>44. (2)νd+>60 (νd+ represents the Abbe number of the 2nd lens or the 5th lens andθ+ shows the partial dispersion ratio of the 2nd lens or the 5th lens).
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