Patent ID: 6982835

Claim:
A zoom lens formed of only four lens groups arranged along an optical axis, in order from the object side, as follows: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; and a fourth lens group having positive refractive power; wherein the first lens group and the third lens group do not move during zooming; the second and fourth lens groups are moved along the optical axis during zooming; the first lens group includes, in order from the object side, a first lens element having negative refractive power, a second lens element having positive refractive power and a convex lens surface on the object side that is cemented to the first lens element, a third lens element, and a fourth lens element having positive refractive power and a convex lens surface on the object side; the fourth lens group includes, in order from the object side, a first lens element having positive refractive power and a convex lens surface on the object side, a second lens element having a biconcave shape, a third lens element having positive refractive power, and a fourth lens element having positive refractive power; and the following conditions are satisfied: ν d1 <45 N d2 <1.52 ν d2 >63 where ν d1 is the Abbe number of the first lens element of the first lens group at the d-line, N d2 is the refractive index of the second lens element of the first lens group at the d-line, and ν d2 is the Abbe number of the second lens element of the first lens group at the d-line.