Patent ID: 7483221

Claim:
An image reading lens, comprising: in order from an object side thereof, a first lens group including at least one positive lens, wholly having a positive refractive power, and having a convex surface on the object side thereof; a second lens group including at least one positive lens, wholly having a positive refractive power, and a convex surface on the object side thereof; a third lens group of a cemented lens including a positive lens and a negative lens, the third lens group wholly having a negative refractive power and having a convex surface on the object side thereof; an aperture stop; a fourth lens group of a cemented lens including a positive lens and a negative lens, the fourth lens group wholly having a negative refractive power and having a convex surface on an image side thereof; a fifth lens group including at least one positive lens, wholly having a positive refractive power, and having a convex surface on the image side thereof; and a sixth lens group including at least one positive lens, wholly having a positive refractive power, and having a convex surface on the image side thereof; wherein at least all positive lenses in each of the first to sixth lens groups satisfy conditional expression (1), and at least two positive lenses of the first to third lens groups and at least two positive lenses of the fourth to sixth lens groups satisfy conditional expression (2): νd>60.0 (1) Δθ g,d >0.015 (2) wherein Abbe number at the d-line is νd; refractive indexes at the g-line, the d-line, the F-line and the C-line are ng, nd, nF and nC, respectively; relative partial dispersion at the g-line and the d-line is θ g,d =(ng−nd)/(nF−nC); and abnormal dispersion is Δθ g,d =θ g,d −1.365+0.00208×νd.