# US 2017/0254992 A1 · Zoom lens and image pickup apparatus including same

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- Number: US 2017/0254992 A1
- Document ID: US20170254992A1
- Status: Published application
- Kind: A1
- Application number: 15/449,052
- Filed: 2017-03-03
- Published: 2017-09-07
- Earliest claimed: 2016-03-07
- Assignees: Canon Kabushiki Kaisha
- Applicants: Canon Kabushiki Kaisha
- Inventors: Yutaka Iriyama
- Web page: https://patentgrep.com/patent/US20170254992A1

## CPC

- G02B 15/1431: {the first group being positive}
- G02B 15/24: having a front fixed lens or lens group and two movable lenses or lens groups in front of a fixed lens or lens group
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

In a zoom lens in which the interval between adjacent lens units changes during zooming, a magnification-varying lens group includes a lens group V having a negative refractive power and a lens unit C having a negative or positive refractive power. The lens group V includes a first magnification-varying lens group V1 including a lens unit V1a having a negative refractive power and a lens unit V1b having a negative refractive power. The lens units V1a and V1b move toward the image side such that the interval between the two lens units is largest at the telephoto end. The lens unit interval m1 on the optical axis between the lens units V1a and V1b at the wide angle end and the maximum lens unit interval m2 on the optical axis between the lens units V1a and V1b during zooming are set as appropriate.

## Claims

### Claim 1

A zoom lens comprising, in order from an object side to an image side, a front lens group having a positive refractive power that does not move for zooming, a magnification-varying lens group including a plurality of lens units that move during zooming, and a rear lens group having a positive refractive power that does not move for zooming, an interval between the lens units adjacent each other being changed during zooming,
wherein the magnification-varying lens group includes a lens group V having a negative refractive power and a lens unit C having a negative or positive refractive power,
the lens group V includes a first magnification-varying lens group V1 including in order from the object side to the image side, a lens unit V1a having a negative refractive power and a lens unit V1b having a negative refractive power,
during zooming from a wide angle end to a telephoto end, both the lens unit V1a and the lens unit V1b move to the image side such that an interval between the lens unit V1a and the lens unit V1b is largest at the telephoto end, and
a conditional expression of
0.40<m1/m2<0.98
is satisfied, where m1 is a lens unit interval on an optical axis between the lens unit V1a and the lens unit V1b at the wide angle end, and m2 is a maximum lens unit interval on the optical axis between the lens unit V1a and the lens unit V1b during zooming.

### Claim 2 (depends on 1)

The zoom lens according to claim 1, wherein a conditional expression of
6.0<Ft/Fw<40.0
is satisfied, where Fw is a focal length of the zoom lens at the wide angle end, and Ft is a focal length of the zoom lens at the telephoto end.

### Claim 3 (depends on 1)

The zoom lens according to claim 1, wherein
the front lens group includes in order from the object side to the image side, a lens subunit F1a having a negative refractive power that does not move for focusing, a lens subunit F1b having a positive refractive power that moves during focusing, and a lens subunit F1c having a positive refractive power that does not move for focusing, and
the lens subunit F1c includes a plurality of positive lenses.

### Claim 4 (depends on 1)

The zoom lens according to claim 1, wherein the lens group V includes a second magnification-varying lens unit V2 on the image side of the first magnification-varying lens group V1, the second magnification-varying lens unit V2 having a negative refractive power that moves along a locus convex to the object side during zooming from the wide angle end to the telephoto end.

### Claim 5 (depends on 1)

The zoom lens according to claim 1, wherein the lens unit C moves along a locus convex to the object side during zooming from the wide angle end to the telephoto end.

### Claim 6 (depends on 1)

The zoom lens according to claim 1, wherein the lens unit V1a includes one negative lens.

### Claim 7 (depends on 1)

The zoom lens according to claim 1, wherein the lens unit V1b includes in order from the object side to the image side, a cemented lens, a positive lens, and a negative lens disposed, the cemented lens being constituted by a positive lens and a negative lens joined to each other.

### Claim 8 (depends on 1)

The zoom lens according to claim 1, wherein the lens unit V1b includes in order from the object side to the image side, a cemented lens and a positive lens disposed, the cemented lens including a positive lens and a negative lens joined to each other.

### Claim 9 (depends on 4)

The zoom lens according to claim 4, wherein the second magnification-varying lens unit V2 includes a cemented lens including a negative lens and a positive lens joined to each other.

### Claim 10

An image pickup apparatus comprising:
a zoom lens comprising in order from an object side to an image side, a front lens group having a positive refractive power that does not move for zooming, a magnification-varying lens group including a plurality of lens units that move during zooming, and a rear lens group having a positive refractive power that does not move for zooming, an interval between the lens units adjacent each other being changed during zooming,
wherein the magnification-varying lens group includes a lens group V having a negative refractive power and a lens unit C having a negative or positive refractive power,
the lens group V includes a first magnification-varying lens group V1 including in order from the object side to the image side, a lens unit V1a having a negative refractive power and a lens unit V1b having a negative refractive power,
during zooming from a wide angle end to a telephoto end, both the lens unit V1a and the lens unit V1b move to the image side such that an interval between the lens unit V1a and the lens unit V1b is largest at the telephoto end, and
a conditional expression of
0.40<m1/m2<0.98
is satisfied, where m1 is a lens unit interval on an optical axis between the lens unit V1a and the lens unit V1b at the wide angle end, and m2 is a maximum lens unit interval on the optical axis between the lens unit V1a and the lens unit V1b during zooming; and
a solid-state image pickup element that receives an image formed by the zoom lens.