# US 2014/0153107 A1 · Zoom lens and imaging apparatus

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- Number: US 2014/0153107 A1
- Document ID: US20140153107A1
- Status: Published application
- Kind: A1
- Application number: 14/174,284
- Filed: 2014-02-06
- 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/US20140153107A1

## CPC

- G02B 13/04: Reversed telephoto objectives
- G02B 15/177: having a negative front lens or group of lenses
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A zoom lens includes: a first lens group having a negative refractive power; and a second lens group having a positive refractive power, provided in this order from an object side. Magnification is changed by moving the first lens group and the second lens group. The first lens group includes 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, provided in this order from the object side. The zoom lens satisfies predetermined conditional formulae.

## 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, provided in this order from an object side;
the first lens group and the second lens group being moved to change magnification;
the first lens group substantially consisting 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, in this order from the object side; and
the zoom lens satisfying the following conditional formulae:
−0.11<fw/fG12<0.12 (1-1)
0.31<fw/f2<0.49 (2-1)
wherein fG12 is the focal length of the second lens from the object side within the first lens group, fw is the focal length of the entire system at a wide angle end, and f2 is the focal length of the second lens group.

### Claim 2 (depends on 1)

A zoom lens as defined in claim 1, in which the focal lengths fG12, fw, and f2 satisfy at least one of the following conditional formulae:
−0.01<fw/fG12<0.06 (1-2)
0.31<fw/f2<0.35 (2-2).

### Claim 3

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, provided in this order from an object side;
the first lens group and the second lens group being moved to change magnification;
the first lens group substantially consisting 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, in this order from the object side; and
the zoom lens satisfying the following conditional formulae:
−0.04<fw/fG12<0.50 (1-3)
0.00<fw/f2<0.35 (2-3)
wherein fG12 is the focal length of the second lens from the object side within the first lens group, fw is the focal length of the entire system at a wide angle end, and f2 is the focal length of the second lens group.

### Claim 4 (depends on 3)

A zoom lens as defined in claim 3, in which the focal lengths fG12, fw, and f2 satisfy at least one of the following conditional formulae:
−0.01<fw/fG12<0.20 (1-4)
0.21<fw/f2<0.35 (2-4).

### Claim 5 (depends on 3)

A zoom lens as defined in claim 3, in which the focal lengths fG12, fw, and f2 satisfy at least one of the following conditional formulae:
−0.01<fw/fG12<0.06 (1-2)
0.31<fw/f2<0.35 (2-2).

### Claim 6

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, provided in this order from an object side;
the first lens group and the second lens group being moved to change magnification;
the first lens group substantially consisting 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, in this order from the object side;
the second lens group substantially consisting of four lenses; and
the zoom lens satisfying the following conditional formulae:
−0.04<fw/fG12<0.50 (1-3)
0.00<fw/f2<0.43 (2-7)
wherein fG12 is the focal length of the second lens from the object side within the first lens group, fw is the focal length of the entire system at a wide angle end, and f2 is the focal length of the second lens group.

### Claim 7 (depends on 6)

A zoom lens as defined in claim 6, in which the focal lengths fG12, fw, and f2 satisfy at least one of the following conditional formulae:
−0.01<fw/fG12<0.20 (1-4)
0.21<fw/f2<0.35 (2-4).

### Claim 8 (depends on 6)

A zoom lens as defined in claim 6, in which the focal lengths fG12, fw, and f2 satisfy at least one of the following conditional formulae:
−0.01<fw/fG12<0.06 (1-2)
0.31<fw/f2<0.35 (2-2).

### Claim 9 (depends on 1)

A zoom lens as defined in claim 1 that satisfies the following conditional formula:
0.00<|fw/f1|<0.64 (3)
wherein fw is the focal length of the entire system at the wide angle end, and f1 is the focal length of the first lens group.

### Claim 10 (depends on 1)

A zoom lens as defined in claim 1 that satisfies the following conditional formula:
0.56<|f1/f2|<1.04 (4)
wherein f1 is the focal length of the first lens group G1, and f2 is the focal length of the second lens group.

### Claim 11 (depends on 1)

A zoom lens as defined in claim 1 that satisfies the following conditional formula:
−0.19<f1/fG12<0.50 (5)
wherein f1 is the focal length of the first lens group and fG12 is the focal length of the second lens from the object side within the first lens group.

### Claim 12 (depends on 1)

A zoom lens as defined in claim 1 that satisfies the following conditional formula:
0.20<HG12F·{(1/r′G12F)−(1/r″G12F)} (6)
wherein HG12F is maximum effective radius of the surface toward the object side of the second lens from the object side within the first lens group, r′G12F is the radius of curvature of a spherical surface that passes through the center of the surface of the second lens toward the object side and a point at a height HG12F from the optical axis and has the center of the surface as its apex, and r″G12F is the radius of curvature of a spherical surface that passes through the center of the surface of the second lens toward the object side and a point at a height HG12F·0.5 from the optical axis and has the center of the surface as its apex.

### Claim 13 (depends on 1)

A zoom lens as defined in claim 1 that satisfies the following conditional formula:
2.0<(rG12F+rG12R)/(rG12F−rG12R)<30.0 (7)
wherein rG12F is the paraxial radius of curvature of the surface toward the object side of the second lens from the object side within the first lens group, and rG12R is the paraxial radius of curvature of the surface toward the image side of the second lens from the object side within the first lens group.

### Claim 14 (depends on 1)

A zoom lens as defined in claim 1 that satisfies the following conditional formula:
2.5<(rG11F+rG11R)/(rG11F−rG11R)<10.0 (8)
wherein rG11F is the paraxial radius of curvature of the surface toward the object side of the first lens from the object side within the first lens group, and rG11R is the paraxial radius of curvature of the surface toward the image side of the first lens from the object side within the first lens group.

### Claim 15 (depends on 1)

A zoom lens as defined in claim 1 that satisfies the following conditional formula:
1.3<fG21/fG22<3.0 (9)
wherein fG21 is the focal length of the first lens from the object side within the second lens group, and fG22 is the focal length of the second lens from the object side within the second lens group.

### Claim 16 (depends on 1)

An imaging apparatus comprising a zoom lens as defined in claim 1.

### Claim 17 (depends on 3)

An imaging apparatus comprising a zoom lens as defined in claim 3.

### Claim 18 (depends on 6)

An imaging apparatus comprising a zoom lens as defined in claim 6.