Patent ID: 9720208
Date: 2017-08-01
CPC Classifications: G02B

Claim:
1. An inner focusing lens comprising sequentially from an object side thereof: a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a negative refractive power, wherein the first lens group includes farthest on an object side thereof, at least one negative meniscus lens, focusing is performed from a focus state at infinity to a focus state for a minimum object distance by moving the second lens group along an optical axis, from the object side to an image side such that an interval between the first lens group and the second lens group increases and an interval between the second lens group and the third lens group decreases, while the first lens group and the third lens group remain fixed, and the inner focusing lens satisfies a conditional expression (1) f3/f≦−29.1, where f3 is a focal length of the third lens group at the focus state at infinity and f is an overall optical-system focal length at the focus state at infinity.