| 摘要 |
Positive first and second lenses each having a convex surface directed onto the object side, a negative third lens having a concave surface directed onto an image side, a negative fourth lens having a concave surface directed onto the object side, and positive fifth and sixth lenses each having a convex surface directed onto the image side are successively disposed from the object side, and predetermined conditional expressions are satisfied, thus yielding an image readout imaging lens suitable for reading out color originals. Successively from the object side, positive first and second lenses L1 and L2 each having a convex surface directed onto the object side, a negative third lens L3 having a concave surface directed onto an image side, a negative fourth lens L4 having a concave surface directed onto the object side, and positive fifth and sixth lenses L5 and L6 each having a convex surface directed onto the image side are disposed, and the following conditional expressions (1) to (6) are satisfied: Nda+0.015 nu da>2.58 (1) Ndb+0.015 nu db>2.58 (2) 0.59f<fa<1.08f (3) 0.53f<fb<1.60f (4) 0.46<fa/fb<1.23 (5) -0.56f<f4<-0.31f (6)
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