Color image readout lens and device using the same

A color image readout lens comprising four lens groups of positive, positive or negative, negative, and positive refractive power, respectively, in order from the object side, as follows:

• a first lens group formed of only a single lens element, said single lens element having a convex surface on the object side;
• a second lens group formed of, in order from the object side, a biconvex lens element that is cemented to a biconcave lens element;
• a stop;
• a third lens group formed of, in order from the object side, a fourth lens element that is cemented to a fifth lens element, with the fifth lens element having positive refractive power and a convex surface on the image side;
• and
• a fourth lens group formed of a single lens element having a convex surface on the image side;
• wherein the following Conditions (1) to (6) are satisfied
• 33<νi<45 Condition (1)
• −0.012<δθi<−0.004 Condition (2)
• 0.0006<Σφi·δθi<<0.0020 Condition (3)
• n2>n3 Condition (4)
• 5<ν2−ν3<15 Condition (5)
• 0.02<(D6−D5)/f<0.08 Condition (6)
• where
• νi is the Abbe number of the ith lens element, in order from the object side, with i=3, 4;
• δθi is the anomalous dispersion of the ith lens element, in order from the object side, with i=3,4;
• Σφi·δθi represents the sum of the products of the refractive power and anomalous dispersion of the ith lens elements, in order from the object side, with i=3, 4;
• n2 is the refractive index of the second lens element, in order from the object side;
• n3 is the refractive index of the third lens element, in order from the object side;
• and
• ν2 is the Abbe number at the d line of the second lens element, in order from the object side,
• ν3 is the Abbe number at the d line of the third lens element, in order from the object side,
• D5 is the distance between the third lens element, in order from the object side, and the stop, and
• D6 is the distance between the stop and the fourth lens element, in order from the object side.