Patent ID: 9116333
Filing Date: 2015-08-25
Classification: G02B,G03B

Abstract:
1. A zoom lens consisting of four lens groups 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, which are in this order from an object side; and a stop located between a most image-side surface of the second lens group and a most image-side surface of the third lens group, wherein distances between the lens groups change when magnification is changed from a wide angle end to a telephoto end, wherein the first lens group consists of a cemented lens of a negative lens and a positive lens in this order from the object side, and wherein the third lens group consists of a positive lens, a cemented lens of a positive lens and a negative lens, a negative meniscus lens with its concave surface facing the object side, and a biconvex lens, which are in this order from the object side, and wherein the following conditional formula (1) and (4-2) are satisfied: R16: a paraxial curvature radius of the object-side surface of the negative meniscus lens in the third lens group, R17: a paraxial curvature radius of an image-side surface of the negative meniscus lens in the third lens group, and R18: a paraxial curvature radius of an object-side surface of the biconvex lens in the third lens group.