Patent ID: 7463427

Claim:
A zoom lens consisting of a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power, and a fourth lens group having positive refracting power, which are disposed in order from an object side, wherein the first lens group and the third lens groups are stationary, and the zoom lens performs mainly variable power by shifting the second lens group in an optical axis direction, and performs correction for image position fluctuations and focusing by shifting the fourth lens group in the optical axis direction, characterized in that: said first lens group is composed of five lenses: a concave lens; a convex lens with a strong convexity facing to an image side; a cemented lens composed of a concave lens with a strong concavity facing to the image side, and a convex lens; and a convex lens with a strong convexity facing to the object side, which are disposed in order from the object side, and is configured so as to satisfy each of the following conditional expressions: (1) 1.25< h 1-4/ h 1-1<1.55; (2) d 1-2/ d 1-3<0.4; (3) 1.65<n1-2; and (4) 0.1< H 1′ /f 1<0.6, where: f 1 is a focal length of the first lens group; h 1 -i is a paraxial ray height in the i-th surface from the object side when allowing a paraxial ray parallel to an optical axis to enter the first lens group; d 1 -i is axial spacing from the i-th surface to the (i+1)-th surface in the first lens group; n 1 -i is a refractive index on a d-line of the i-th lens in the first lens group; and H 1 ′ is spacing from a vertex of a surface closest to the image side in the first lens group to a principal point on the image side in the first lens group (“−” indicates the object side, and “+” indicates the image side).