CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2019-050032, filed on Mar. 18, 2019 and Japanese Patent Application No. 2020-004480, filed on Jan. 15, 2020, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.

BACKGROUND

Technical Field

Embodiments of the present disclosure relate to a zoom lens, a lens barrel, and an imaging device.

Related Art

Conventionally, various types of zoom lenses are mounted on digital cameras, such as digital camera single-lens reflex cameras, which is an example of an imaging device. In particular, a positive-lead zoom lens that includes, sequentially from the object side, a positive group, a negative group, and a rear group is used as a zoom lens system, whose focal length on the telephoto side (long focal length end side) is extended. Such a zoom lens system needs to be a compact-sized optical system having higher optical performance over the entire zoom and shooting-distance range. In addition, in order to achieve a high-speed automatic focusing operation (autofocus) and reduce the weight of the focusing lens group, the inner focus method is typically known that moves a lens group at the inner side relative to a heavier front lens.

SUMMARY

In one aspect of this disclosure, there is provided zoom lens system including a first lens group having positive refractive power; a second lens group has negative refractive power; and a subsequent lens group. The second lens group consists of a second lens group-a having positive refractive power, a second lens group-b having negative refractive power, and a second lens group-c having negative refractive power arranged in that order from the object side. The first lens group, the second lens group, and the subsequent lens group are disposed in that order from the object side. A distance between the first lens group and the second lens group increasing and a distance between the second lens group and the subsequent lens group decreases during a change in magnification from a short focal length end to a long focal length end. During a change in focus from infinity to a short distance, the second lens group-b is movable to the image side, and a distance between the second lens group-a and the second lens group-b and a distance between the second lens group-b and the second lens group-c are changeable.

In another aspect of this disclosure, there is provided an improved lens barrel including the above-described zoom lens system.

In still another aspect of this disclosure, there is provided an improved imaging device including the above-described zoom lens system.

