# US 2014/0153106 A1 · Zoom lens and imaging apparatus

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- Number: US 2014/0153106 A1
- Document ID: US20140153106A1
- Status: Published application
- Kind: A1
- Application number: 14/173,409
- Filed: 2014-02-05
- Published: 2014-06-05
- Earliest claimed: 2011-08-29
- Assignees: FUJIFILM Corporation
- Applicants: FUJIFILM Corporation
- Inventors: Hiroki SAITO; Michio CHO; Toru ITO
- Web page: https://patentgrep.com/patent/US20140153106A1

## CPC

- G02B 13/04: Reversed telephoto objectives
- G02B 13/009: {having zoom function}
- G02B 13/18: with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)}
- G02B 15/142: {having two groups only}
- G02B 15/1425: {the first group being negative}
- G02B 15/177: having a negative front lens or group of lenses
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

In a zoom lens in which a first lens group having a negative refractive power and a second lens group having a positive refractive power are disposed in order from the object side and zooming is performed by moving the first and the second lens groups, the first lens group is formed of a first lens having a negative refractive power, a second lens, a third lens having a negative refractive power, and a fourth lens having a positive refractive power. Then, when the focal length of the second lens, the focal length of the entire system at the wide angle end, the focal length of the first lens group, and the focal length of the second lens group are taken as fG12, fw, f1, and f2 respectively, the zoom lens is configured to satisfy conditional expressions give below: 0.00<fw/f2<0.50 (1-1); and −0.19<f1/fG12<0.16 (2-1).

## Claims

### Claim 1

A zoom lens substantially consisting of a first lens group having a negative refractive power and a second lens group having a positive refractive power, disposed in order from the object side, wherein:
zooming is performed by moving the first lens group and the second lens group;
the first lens group is substantially composed of a first lens having a negative refractive power, a second lens, a third lens having a negative refractive power, and a fourth lens having a positive refractive power; and
when the focal length of the second lens from the object side in the first lens group is taken as fG12, the focal length of the entire system at the wide angle end is taken as fw, the focal length of the first lens group is taken as f1, and the focal length of the second lens group is taken as f2, the zoom lens satisfies conditional expressions given below:
0.00<fw/f2<0.50 (1-1); and
−0.19<f1/fG12<0.16 (2-1).

### Claim 2 (depends on 1)

The zoom lens of claim 1, wherein the zoom lens satisfies at least either one of conditional expressions given below with respect to the focal lengths fG12, fw, f1 and f2:
0.20<fw/f2<0.43 (1-2); and
−0.15<f1/fG12<0.10 (2-2).

### Claim 3 (depends on 1)

The zoom lens of claim 1, wherein the zoom lens satisfies a conditional expression given below with respect to the focal lengths fw and f2:
0.31<fw/f2<0.35 (1-3).

### Claim 4

A zoom lens substantially consisting of a first lens group having a negative refractive power and a second lens group having a positive refractive power, disposed in order from the object side, wherein:
zooming is performed by moving the first lens group and the second lens group;
the first lens group is substantially composed of a first lens having a negative refractive power, a second lens, a third lens having a negative refractive power, and a fourth lens having a positive refractive power;
the second lens group is substantially composed of four lenses; and
when the focal length of the second lens from the object side in the first lens group is taken as fG12, the focal length of the entire system at the wide angle end is taken as fw, the focal length of the first lens group is taken as f1, and the focal length of the second lens group is taken as f2, the zoom lens satisfies conditional expressions given below:
0.00<fw/f2<0.43 (1-4); and
−1.00<f1/fG12<0.16 (2-3).

### Claim 5 (depends on 4)

The zoom lens of claim 4, wherein the zoom lens satisfies at least either one of conditional expressions given below with respect to fG12, fw, f1, and f2:
0.20<fw/f2<0.43 (1-2); and
−0.50<f1/fG12<0.10 (2-4).

### Claim 6 (depends on 4)

The zoom lens of claim 4, wherein the zoom lens satisfies at least either one of conditional expressions given below with respect to fG12, fw, f1, and f2:
0.31<fw/f2<0.35 (1-3); and
−0.15<f1/fG12<0.10 (2-2).

### Claim 7 (depends on 1)

The zoom lens of claim 1, wherein, when the second lens from the object side in the first lens group is taken as fG12 and the focal length of the entire system at the wide angle end is taken as fw, the zoom lens satisfies a conditional expression given below:
−0.11<fw/fG12<0.12 (3)

### Claim 8 (depends on 7)

The zoom lens of claim 7, wherein the zoom lens satisfies a conditional expression given below:
−0.01<fw/fG12<0.06 (3′)

### Claim 9 (depends on 1)

The zoom lens of claim 1, wherein, when the focal length of the first lens group is taken as f1 and the focal length of the second lens group is taken as f2, the zoom lens satisfies a conditional expression given below:
0.56<|f1/f2|<1.04 (4).

### Claim 10 (depends on 9)

The zoom lens of claim 9, wherein the zoom lens satisfies a conditional expression given below:
0.70<|f1/f2|<0.80 (4′).

### Claim 11 (depends on 1)

The zoom lens of claim 1, wherein, when the focal length of the entire system at the wide angle end is taken as fw and the focal length of the first lens group is taken as f1, the zoom lens satisfies a conditional expression given below:
0.00<|fw/f1|<0.63 (5).

### Claim 12 (depends on 11)

The zoom lens of claim 11, wherein the zoom lens satisfies a conditional expression given below:
0.20<|fw/f1|<0.50 (5′).

### Claim 13 (depends on 1)

The zoom lens of claim 1, wherein, when the maximum effective radius of the object side surface of the second lens from the object side in the first lens group is taken as HG12F, the radius of curvature of a spherical surface passing through the center of the object side surface of the second lens and a point on the object side surface at a height of HG12F from the optical axis with the center of the object side surface as the apex of the spherical surface is taken as r′G12F, and the radius of curvature of a spherical surface passing through the center of the object side surface of the second lens and a point on the object side surface at a height of HG12F×0.5 from the optical axis with the center of the object side surface as the apex of the spherical surface is taken as r″G12F, the zoom lens satisfies a conditional expression given below:
0.20<HG12F×{(1/r′G12F)−(1/r″G12F)} (6).

### Claim 14 (depends on 1)

The zoom lens of claim 1, wherein, when the paraxial radius of curvature of the object side surface of the second lens from the object side in the first lens group is taken as rG12F and the paraxial radius of curvature of the image side surface of the second lens from the object side in the first lens group is taken as rG12R, the zoom lens satisfies a conditional expression given below:
2.0<(rG12F+rG12R)/(rG12F−rG12R)<30.0 (7).

### Claim 15 (depends on 1)

The zoom lens of claim 1, wherein, when the paraxial radius of curvature of the object side surface of the first lens from the object side in the first lens group is taken as rG11F and the paraxial radius of curvature of the image side surface of the first lens from the object side in the first lens group is taken as rG11R, the zoom lens satisfies a conditional expression given below:
2.5<(rG11F+rG11R)/(rG11F−rG11R)<10.0 (8).

### Claim 16 (depends on 1)

The zoom lens of claim 1, wherein, when the focal length of the first lens from the object side in the second lens group is taken as fG21 and the focal length of the second lens from the object side in the second lens group G2 is taken as fG22, the zoom lens satisfies a conditional expression given below:
1.3<fG21/fG22<3.0 (9).

### Claim 17 (depends on 1)

An imaging apparatus, comprising the zoom lens of claim 1.

### Claim 18 (depends on 4)

An imaging apparatus, comprising the zoom lens of claim 4.