# US 2013/0155312 A1 · Zoom lens and imaging apparatus

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- Number: US 2013/0155312 A1
- Document ID: US20130155312A1
- Status: Published application
- Kind: A1
- Application number: 13/661,938
- Filed: 2012-10-26
- Published: 2013-06-20
- Earliest claimed: 2011-12-14
- Assignees: Sony Corporation
- Inventors: Takumi Matsui
- Web page: https://patentgrep.com/patent/US20130155312A1

## CPC

- G02B 15/144113: {arranged +-++}
- G02B 13/18: with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)}
- G02B 15/173: arranged +-+
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

Disclosed herein is a zoom lens, including: a first lens group having a positive refracting power; a second lens group having a negative refracting power; a third lens group having a positive refracting power; and a fourth lens group having a positive refracting power; the first, second, third and fourth lens groups being disposed in order from the object side; the lens groups moving upon zooming from a wide angle end to a telephoto end of the zoom lens such that the distance between the first lens group and the second lens group increases while the distance between the second lens group and the third lens group decreases.

## Claims

### Claim 1

A zoom lens, comprising:
a first lens group having a positive refracting power;
a second lens group having a negative refracting power;
a third lens group having a positive refracting power; and
a fourth lens group having a positive refracting power,
the first, second, third and fourth lens groups being disposed in order from an object side,
the lens groups moving upon zooming from a wide angle end to a telephoto end of the zoom lens such that the distance between the first lens group and the second lens group increases while the distance between the second lens group and the third lens group decreases,
the first lens group being configured from a negative lens having a meniscus shape and a positive lens having a convex face on the opposite sides thereof, the negative lens and the positive lens being disposed in order from the object side,
the second lens group being configured from a negative lens, another negative lens having a concave face on the opposite sides thereof, and a positive lens, the negative lenses and the positive lens being disposed in order from the object side,
the third lens group being configured from a positive lens, a negative lens and another positive lens disposed in order from the object side,
the fourth lens group being configured from a positive lens.

### Claim 2 (depends on 1)

The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression (a):
0.95<|F2/FW|<1.25 (a)
where F2 is the focal length of the second lens group, and FW the focal length of the zoom lens at the wide angle end.

### Claim 3 (depends on 1)

The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression (b):
0.75<|β3W|<1.0 (b)
where β3W is the lateral magnification of the third lens group at the wide angle end.

### Claim 4 (depends on 1)

The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression (c):
0.9<L2/IM<1.3 (c)
where L2 is the distance from the vertex of the object side face of the negative lens on the object side to the vertex of the image side face of the positive lens in the second lens group, and IM is a maximum image height within a recording range on the image plane.

### Claim 5 (depends on 1)

The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression (d):
6.0<|Tan(ωW)/Tan(ωT)|<16.0 (d)
where ωW is the half angle of view of the zoom lens at the wide angle end, and ωT is the half angle of view of the zoom lens at the telephoto end.

### Claim 6 (depends on 1)

The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression (e):
5.0<F1/FW<7.5 (e)
where F1 is the focal length of the first lens group, and FW the focal length of the zoom lens at the wide angle end.

### Claim 7 (depends on 1)

The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression (f):
1.0<|LT/FT|<1.5 (f)
where LT is the overall optical length at the telephoto end of the zoom lens, and FT the focal length of the zoom lens at the telephoto end.

### Claim 8 (depends on 1)

The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression (g):
0.5<F1/FT<1.2 (g)
where F1 is the focal length of the first lens group, and FT the focal length of the zoom lens at the telephoto end.

### Claim 9 (depends on 1)

The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression (h):
2.1<|β3T/β3W|<2.6 (h)
where β3T is the lateral magnification of the third lens group at the telephoto end, and β3W is the lateral magnification of the third lens group at the wide angle end.

### Claim 10 (depends on 1)

The zoom lens according to claim 1, wherein
the negative lens and the positive lens of the first lens group are joined together to form a cemented lens, and
the second negative lens and the third positive lens from the object side in the second lens group are not joined together.

### Claim 11 (depends on 1)

The zoom lens according to claim 1, wherein the image side face of the positive lens of the first lens group and the object side face and the image side face of the negative lens positioned on the most object side in the second lens group have an aspheric face shape.

### Claim 12 (depends on 1)

The zoom lens according to claim 1, further comprising
an aperture stop provided between the second lens group and the third lens group and movable, upon zooming, integrally with the third lens group such that an F value is defined at each zoom position.

### Claim 13 (depends on 1)

The zoom lens according to claim 1, wherein the positive lens on the object side and the negative lens of the third lens group are formed as a cemented lens wherein the lenses are joined together.

### Claim 14 (depends on 1)

The zoom lens according to claim 1, wherein, upon focusing on an object, only the fourth lens group moves, and the zoom lens satisfies the following conditional expression (i):
0.2<FM/FT<0.8 (i)
where FM is the focal length of the fourth lens group at the zoom position at which the positive lens of the fourth lens group is positioned nearest to the image side upon focusing on an infinitely remotely positioned object, and FT the focal length of the zoom lens at the telephoto end.

### Claim 15

An imaging apparatus, comprising:
a zoom lens including a first lens group having a positive refracting power, a second lens group having a negative refracting power, a third lens group having a positive refracting power, and a fourth lens group having a positive refracting power, the first, second, third and fourth lens groups being disposed in order from the object side, the lens groups moving upon zooming from a wide angle end to a telephoto end of the zoom lens such that the distance between the first lens group and the second lens group increases while the distance between the second lens group and the third lens group decreases; and
an imaging device configured to convert an optical image formed by the zoom lens into an electric signal,
the first lens group being configured from a negative meniscus lens and a positive lens having a convex face on the opposite sides thereof, the negative lens and the positive lens being disposed in order from the object side,
the second lens group being configured from a negative lens, another negative lens having a concave face on the opposite sides thereof, and a positive lens, the negative lenses and the positive lens being disposed in order from the object side,
the third lens group being configured from a positive lens, a negative lens and another positive lens disposed in order from the object side,
the fourth lens group being configured from a positive lens.