# US 11,307,392 B2 · Variable magnification optical system, imaging apparatus, and method for manufacturing variable magnification optical system

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- Number: US 11,307,392 B2
- Document ID: US11307392B2
- Status: Granted
- Kind: B2
- Application number: 16/886,757
- Filed: 2020-05-28
- Published: 2020-09-17
- Granted: 2022-04-19
- Earliest claimed: 2013-05-31
- Assignees: Nikon Corporation
- Applicants: Nikon Corporation
- Inventors: Hiroshi Yamamoto; Satoru Shibata
- Web page: https://patentgrep.com/patent/US11307392B2

## CPC

- G02B 15/144113: {arranged +-++}
- G02B 13/009: {having zoom function}
- G02B 15/144105: {arranged +-+-}
- G02B 27/646: {compensating for small deviations, e.g. due to vibration or shake (movement of one or more optical elements for control of motion blur in cameras, projectors or printers G03B2205/0007; image stabilisation in cameras peculiar to the presence or use of an electronic image sensor H04N23/68)}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

Provided is a variable magnification optical system comprising, in order from an object side along an optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a fourth lens group G4; upon zooming from a wide angle end state to a telephoto end state, a distance between the first lens group G1 and the second lens group G2 being varied, a distance between the second lens group G2 and the third lens group G3 being varied, and a distance between the third lens group and the fourth lens group being varied; the third lens group G3 comprising, in order from the object side along the optical axis, a 3a-th lens group G3a having positive refractive power, an aperture S, and a 3b-th lens group G3b having positive refractive power; a lens group having negative refractive power within the 3b-th lens group G3b being used as a vibration reduction lens group and moved so as to include a component in a direction orthogonal to the optical axis, whereby image plane correction is performed when image blurring occurs; and predetermined conditions being satisfied. Whereby, a small-size and high-performance variable magnification optical system, capable of realizing a small variation in aberration and attaining a sufficient brightness even in the telephoto state, an imaging apparatus, and a method for manufacturing the variable magnification optical system are provided.

## Claims

### Claim 1

A variable magnification optical system comprising, in order from an object side along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group;
upon zooming from a wide angle end state to a telephoto end state, the first lens group, the second lens group, the third lens group and the fourth lens group being moved along the optical axis, respectively;
the first lens group comprising one negative lens and one positive lens;
the third lens group comprising, in order from the object side along the optical axis, a 3a-th lens group having positive refractive power, an aperture, and a 3b-th lens group having positive refractive power; and
the conditions of the following expressions being satisfied:
|f3a/f4|<0.540
|f3b/f4|<1.00
where f3a denotes a focal length of the 3a-th lens group, f4 denotes a focal length of the fourth lens group, and f3b denotes a focal length of the 3b-th lens group.

### Claim 2 (depends on 1)

A variable magnification optical system according to claim 1, wherein the condition of the following expression is satisfied:
0.100<f3a/f3b<0.700.

### Claim 3 (depends on 1)

A variable magnification optical system according to claim 1, wherein the 3b-th lens group comprises at least one negative lens component, and the condition of the following expression is satisfied:
0.700<(−f3bn)/f3a<1.500
where f3bn denotes a focal length of the negative lens component on the most image side within the 3b-th lens group.

### Claim 4 (depends on 1)

An imaging apparatus equipped with the variable magnification optical system according to claim 1.

### Claim 5

A variable magnification optical system comprising, in order from an object side along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group;
upon zooming from a wide angle end state to a telephoto end state, the first lens group, the second lens group, the third lens group and the fourth lens group being moved along the optical axis, respectively;
the first lens group comprising one negative lens and one positive lens;
the third lens group comprising, in order from the object side along the optical axis, a 3a-th lens group having positive refractive power, an aperture, and a 3b-th lens group having positive refractive power;
the 3b-th lens group comprising at least one negative lens component; and
the conditions of the following expressions being satisfied:
|f3a/f4|<1.00
0.700<(−f3bn)/f3a<1.500
where f3a denotes a focal length of the 3a-th lens group, f4 denotes a focal length of the fourth lens group, and f3bn denotes a focal length of the negative lens component on the most image side within the 3b-th lens group.

### Claim 6 (depends on 5)

A variable magnification optical system according to claim 5, wherein the condition of the following expression is satisfied:
0.100<f3a/f3b<0.700
where f3b denotes a focal length of the 3b-th lens group.

### Claim 7 (depends on 5)

A variable magnification optical system according to claim 5, wherein the condition of the following expression is satisfied:
|f3b/f4|<1.00
where f3b denotes a focal length of the 3b-th lens group.

### Claim 8 (depends on 5)

An imaging apparatus equipped with the variable magnification optical system according to claim 5.

### Claim 9

A method for manufacturing a variable magnification optical system comprising, in order from an object side along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group;
the method comprising:
constructing, upon zooming from a wide angle end state to a telephoto end state, the first lens group, the second lens group, the third lens group and the fourth lens group to be moved along the optical axis, respectively;
arranging the first lens group to comprise one negative lens and one positive lens;
arranging the third lens group to comprise, in order from the object side along the optical axis, a 3a-th lens group having positive refractive power, an aperture, and a 3b-th lens group having positive refractive power; and
constructing so as to satisfy the conditions of the following expressions:
|f3a/f4|<0.540
|f3b/f4|<1.00
where f3a denotes a focal length of the 3a-th lens group, f4 denotes a focal length of the fourth lens group, and f3b denotes a focal length of the 3b-th lens group.

### Claim 10 (depends on 9)

A method for manufacturing a variable magnification optical system, according to claim 9, including constructing so as to satisfy the condition of the following expression:
0.100<f3a/f3b<0.700.

### Claim 11 (depends on 9)

A method for manufacturing a variable magnification optical system, according to claim 9, wherein the 3b-th lens group is arranged to comprise at least one negative lens component, and further including constructing so as to satisfy the condition of the following expression:
0.700<(−f3bn)/f3a<1.500
where f3bn denotes a focal length of the negative lens component on the most image side within the 3b-th lens group.

### Claim 12

A method for manufacturing a variable magnification optical system comprising, in order from an object side along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group;
the method comprising:
constructing, upon zooming from a wide angle end state to a telephoto end state, the first lens group, the second lens group, the third lens group and the fourth lens group to be moved along the optical axis, respectively;
arranging the first lens group to comprise one negative lens and one positive lens;
arranging the third lens group to comprise, in order from the object side along the optical axis, a 3a-th lens group having positive refractive power, an aperture, and a 3b-th lens group having positive refractive power;
arranging the 3b-th lens group to include at least one negative lens component; and
constructing so as to satisfy the conditions of the following expressions:
|f3a/f4|<1.00
0.700<(−f3bn)/f3a<1.500
where f3a denotes a focal length of the 3a-th lens group, f4 denotes a focal length of the fourth lens group, and f3bn denotes a focal length of the negative lens component on the most image side within the 3b-th lens group.

### Claim 13 (depends on 12)

A method for manufacturing a variable magnification optical system, according to claim 12, including constructing so as to satisfy the condition of the following expression:
0.100<f3a/f3b<0.700
where f3b denotes a focal length of the 3b-th lens group.

### Claim 14 (depends on 12)

A method for manufacturing a variable magnification optical system, according to claim 12, including constructing so as to satisfy the condition of the following expression:
|f3b/f4|<1.00
where f3b denotes a focal length of the 3b-th lens group.