Patent ID: 7212242

Claim:
An electronic image pickup system comprising a zoom lens and an electronic image pickup device located on an image plane side of said zoom lens, wherein said zoom lens comprises, in order from an object side, a first lens group comprising two lens components and having negative power as a whole and a second lens group comprising two lens components and having positive power as a whole wherein an air space between said first lens group and said second lens group is varied to vary focal length of the zoom lens, a total number of lens groups in the zoom lens is only two of the first lens group and the second lens group, a total number of lens components in the first lens group is two, a total number of lens components in the second lens group is two, wherein each of said lens components in the first lens group and the second lens group is a single lens, wherein said first lens group includes at least one surface in which the outermost periphery of an effective refracting surface portion is of concave shape in a direction opposite to a direction with a paraxial center of curvature found in said surface, and following conditions (d),(g),(j),(l) and (m) are satisfied: 30<( t 1 + D 2 )· A< 90 (d) 20< f 21 · A< 42 (g) 40<− f 22 · A< 140 (j) −1<( R 21 + R 22 )/( R 21− R 22 )<0 (l) 0.25<( R 23 + R 24 )/( R 23 −R 24 )<3.4 (m) where A is equal to 43.2/L wherein L is a diagonal length of an effective image pickup area of the electronic image pickup device, t 1 is a total axial thickness of the first lens group, D 2 is a total axial thickness of the second lens group, f 21 is a focal length of an object-side lens component in the two lens components in the second lens group, f 22 is a focal length of an image-side lens component of the two lens components in the second lens group, and R 21 , R 22 , R 23 and R 24 are radii of curvature of refracting surfaces forming the second lens group as viewed in order from an object side of the zoom lens.