Patent ID: 9013805
Filing Date: 2015-04-21
Classification: G02B

Abstract:
1. A zoom lens substantially consisting of 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 in this order form the object side, wherein each of the lens groups is moved such that the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the distance between the third lens group and the fourth lens group decreases while changing magnification from the wide angle end to the telephoto end; the fourth lens group substantially consists of a fourth-a lens group having positive refractive power and a fourth-b lens group having negative refractive power in this order from the object side, and only the fourth-b lens group is moved toward the image side while focusing from an infinity to a close distance; the fourth-a lens group substantially consists of a 4-1st lens having a positive biconvex shape, a 4-2nd lens having a negative meniscus shape with a concave surface toward the image side, and a 4-3rd lens having a positive biconvex shape in this order from the object side; and the fourth-b lens group substantially consists of a 4-4th lens having a positive meniscus shape with a convex surface toward the image side and a 4-5th lens having a negative biconcave shape in this order from the object side.