Patent ID: 8040614

Claim:
A zoom lens comprising: a first lens group having positive refractive power and having a position fixed at all times; a second lens group having negative refractive power and made movable in a direction of an optical axis to vary power; a third lens group having positive refractive power and having a position fixed at all times; a fourth lens group having positive refractive power and made movable in the direction of the optical axis to correct a focal position resulting from power variation and perform focusing; and a fifth lens group having positive refractive power, said first lens group, said second lens group, said third lens group, said fourth lens group, and said fifth lens group being arranged in order from an object side to an image side, said first lens group being formed by arranging a concave lens, a convex lens, a cemented lens of a concave lens and a convex lens, and a convex lens in order from the object side to the image side, and the zoom lens satisfying following conditional expressions (1) and (2), 0.03 <H 1 ′/f 1<0.3 (1) 0.3 <|f 2|/√( fw·ft )<0.65 (2) where H 1 ′ is an interval from a vertex of a surface nearest to the image side in the first lens group to a principal point on the image side of the first lens group (− denotes the object side, and + denotes the image side), f 1 is focal length of the first lens group, f 2 is focal length of the second lens group, fw is focal length of an entire lens system at a wide-angle end, and ft is the focal length of the entire lens system at a telephoto end.