| 摘要 |
PROBLEM TO BE SOLVED: To provide a wide-angle color image read lens which is relatively light and compact and can have aberrations excellently corrected by using four elements in four groups and meeting prescribed conditional expressions. SOLUTION: This lens has a 1st lens group composed of a positive lens L1 which is convex to the object side, a 2nd lens group composed of a negative lens L2 which is concave to the object side, a 3rd lens group composed of a positive lens L3 which is convex to the object side, and a 4th lens group composed of a negative lens L4 which is concave to the object side in order from the object side. The center thickness DR3 of the 3rd lens group, the focal length f4 and Abbe numberν4 of the 4th lens group, the interval DR3-4 between the 3rd lens group and 4th lens group, and the overall lengthΣD of the lens are so set as to meet prescribed conditions respectively. Consequently, the wide-angle color image read lens can be actualized which is relatively light and compact and can have various aberrations excellently corrected.
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