Patent ID: 7817356

Claim:
An imaging lens comprising: a first lens, a second lens, a third lens, and a fourth lens, which are arranged in ascending sequence, starting from a lens nearest to an object, wherein: the first lens has a double-convex shape and positive refractive power; the second lens has a double-concave shape and negative refractive power; the third lens has a meniscus shape with its convex surface facing an image, and has positive refractive power; the fourth lens has a meniscus shape with its convex surface facing the object; and following equations (1) to (5) are fulfilled: 1.55< f/f 1<1.7 (1), 0.9< f/f 3<1.65 (2), −0.004<1/ f 1ν1+1/ f 2ν2<0 (3), |1/ f 3ν3+1/ f 4ν4|<0.015 (4), and 0.12< T 23/ TTL< 0.16 (5), where f: combined focal length of the entire imaging lens, f1: focal length of the first lens, f2: focal length of the second lens, f3: focal length of the third lens, f4: focal length of the fourth lens, ν1: Abbe number of line d of the first lens, ν2: Abbe number of line d of the second lens, ν3: Abbe number of line d of the third lens, ν4: Abbe number of line d of the fourth lens, T23: spacing between the second lens and the third lens, and TTL: distance from an apex of the first lens to an image plane.