Patent ID: 9645382
Date: 2017-05-09
CPC Classifications: G02B

Claim:
1. An objective lens for an endoscope, wherein the objective lens focuses from a farthest point object to a nearest point object by moving, along an optical axis, at least one lens group excluding a most object-side lens group, and wherein the following conditional formulas (1) and (2′) are satisfied: where ft: a focal length of an entire system when the objective lens has been focused on the nearest point object, where an object distance to the nearest point object is dt, fw: a focal length of the entire system when the objective lens has been focused on the farthest point object, where an object distance to the farthest point object is dw, and fm: a focal length of the entire system when the objective lens has been focused on a middle point object, where an object distance to the middle point object is dm, which is represented by dm=(2×dw×dt)/(dw+dt).