Patent ID: 9279966
Filing Date: 2016-03-08
CPC Classification: G02B

Claim Text:
1. A zoom lens consisting of: a first lens group having positive refractive power, and which is fixed during magnification change; a second lens group having negative refractive power, and which moves from an object side toward an image side while magnification is changed from a wide angle end to a telephoto end; a third lens group having negative refractive power, and which corrects movement of an image plane during magnification change; and a fourth lens group having positive refractive power, and which is fixed during magnification change and includes a stop, in this order from the object side, wherein the first lens group consists of a 1a-th lens group having negative refractive power, and which is fixed during focusing, a 1b-th lens group having positive refractive power, and which moves during focusing, and a 1c-th lens group having positive refractive power, and which is fixed during focusing, in this order from the object side, and wherein the second lens group consists of a 2a-th lens group having negative refractive power and a 2b-th lens group having positive refractive power in this order from the object side, and a distance between the 2a-th lens group and the 2b-th lens group is changed during magnification change, and wherein the third lens group moves in such a manner that a distance from the fourth lens group at the telephoto end is narrower than a distance from the fourth lens group at the wide angle end, and wherein the following conditional formulas (1) and (2) are satisfied: L: a length from a most-object-side surface in the first lens group to the stop, fw: a focal length at the wide angle end, and f1b: a focal length of the 1b-th lens group.