# US 7,609,456 B2 · Standard zoom lens system

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- Number: US 7,609,456 B2
- Document ID: US7609456B2
- Status: Granted
- Kind: B2
- Application number: 11/957,718
- Filed: 2007-12-17
- Published: 2008-06-19
- Granted: 2009-10-27
- Earliest claimed: 2006-12-18
- Assignees: Hoya Corporation
- Inventors: Masakazu Saori
- Web page: https://patentgrep.com/patent/US7609456B2

## CPC

- G02B 15/144113: {arranged +-++}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A standard zoom lens system including a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group. Upon zooming from the short focal length extremity to the long focal length extremity, the positive first lens group, the positive third lens group and the positive fourth lens group move toward the object, and the negative second lens group moves toward the image and thereafter moves toward the object. The positive first lens group includes a negative lens element and a positive lens element. The standard zoom lens system satisfies the following conditions: 7.5<f1/|f2|<9.5 (1) 3.0<f1/f3<5.0 (2) wherein f1 designates the focal length of the positive first lens group; f2 designates the focal length of the negative second lens group; and f3 designates the focal length of the positive third lens group.

## Claims

### Claim 1

A standard zoom lens system comprises a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group, in this order from an object,
wherein upon zooming from the short focal length extremity to the long focal length extremity, said positive first lens group, said positive third lens group and said positive fourth lens group move toward the object, and said negative second lens group moves toward an image and thereafter moves toward the object;
wherein said positive first lens group consists of a negative lens element and a positive lens element; and
wherein said standard zoom lens system satisfies the following conditions:
7.5<f1/|f2|<9.5
3.0<f1/f3 <5.0
wherein
f1 designates the focal length of said positive first lens group;
f2 designates the focal length of said negative second lens group; and
f3 designates the focal length of said positive third lens group.

### Claim 2 (depends on 1)

The standard zoom lens system according to claim 1, satisfying the following condition:
7.0<f1/fw<10.0
wherein
f1 designates the focal length of said positive first lens group; and
fw designates the focal length of said entire standard zoom lens system at the short focal length extremity.

### Claim 3 (depends on 1)

The standard zoom lens system according to claim 1, wherein said negative lens element and said positive lens element of said positive first lens group are cemented to each other.

### Claim 4 (depends on 1)

The standard zoom lens system according to claim 1, wherein said negative second lens group comprises two negative lens elements and a positive lens element.

### Claim 5 (depends on 4)

The standard zoom lens system according to claim 4, wherein said negative second lens group comprises a negative meniscus lens element having the convex surface facing toward the object, a negative lens element having a concave surface facing toward the image, and a positive lens element having a convex surface facing toward the object, in this order from the object.

### Claim 6 (depends on 4)

The standard zoom lens system according to claim 4, satisfying the following condition:
0.7 <|f2|/fw <1.2
wherein
f2 designates the focal length of said negative second lens group; and
fw designates the focal length of said entire standard zoom lens system at the short focal length extremity.

### Claim 7 (depends on 4)

The standard zoom lens system according to claim 4, satisfying the following condition:
1.68<Nn<1.79
wherein
Nn designates the refractive index of the d-line of each negative lens element in the negative second lens group.

### Claim 8 (depends on 1)

The standard zoom lens system according to claim 1, wherein said positive fourth lens group comprises one of a positive aspherical lens element and a negative aspherical lens element, and cemented lens elements having a positive lens element and a negative lens element.

### Claim 9 (depends on 1)

The standard zoom lens system according to claim 1, satisfying the following condition:
1.0<f4/f3 <3.0
wherein
f4 designates the focal length of said positive fourth lens group; and
f3 designates the focal length of said positive third lens group.

### Claim 10 (depends on 1)

The standard zoom lens system according to claim 1, satisfying the following condition:
0.6<|f12w|/f34w <0.8
wherein
f12w designates the combined focal length of the positive first lens group and the negative second lens group at the short focal length extremity; and
f34w designates the combined focal length of said positive third lens group and said positive fourth lens group at the short focal length extremity.

### Claim 11

A standard zoom lens system comprises a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group, in this order from an object,
wherein upon zooming from the short focal length extremity to the long focal length extremity, said positive first lens group, said positive third lens group and said positive fourth lens group move toward the object, and said negative second lens group moves toward an image and thereafter moves toward the object;
wherein said positive first lens group comprises a negative lens element and a positive lens element;
wherein said negative second lens group comprises two negative lens elements and a positive lens element; and
wherein said standard zoom lens system satisfies the following conditions:
7.0<f1/fw<10.0
1.68<Nn<1.79
wherein
f1 designates the focal length of said positive first lens group;
fw designates the focal length of said entire standard zoom lens system at the short focal length extremity; and
Nn designates the refractive index of the d-line of each negative lens element in the negative second lens group.

### Claim 12 (depends on 11)

The standard zoom lens system according to claim 11, wherein said negative lens element and said positive lens element of said positive first lens group are cemented to each other.

### Claim 13 (depends on 11)

The standard zoom lens system according to claim 11, wherein said negative second lens group comprises a negative meniscus lens element having the convex surface facing toward the object, a negative lens element having a concave surface facing toward the image, and a positive lens element having a convex surface facing toward the object, in this order from the object.

### Claim 14 (depends on 11)

The standard zoom lens system according to claim 11, satisfying the following condition:
0.7 <1|f2|/fw <1.2
wherein
f2 designates the focal length of said negative second lens group; and
fw designates the focal length of said entire standard zoom lens system at the short focal length extremity.

### Claim 15 (depends on 11)

The standard zoom lens system according to claim 11, wherein said positive third lens group comprises a positive lens element, and cemented lens elements having a positive lens element and a negative lens element.

### Claim 16 (depends on 11)

The standard zoom lens system according to claim 11, wherein said positive fourth lens group comprises one of a positive aspherical lens element and a negative aspherical lens element, and cemented lens elements having a positive lens element and a negative lens element.

### Claim 17 (depends on 11)

The standard zoom lens system according to claim 11, satisfying the following condition:
1.0<f4/f3 <3.0
wherein
f4 designates the focal length of said positive fourth lens group; and
f3 designates the focal length of said positive third lens group.

### Claim 18 (depends on 11)

The standard zoom lens system according to claim 11, satisfying the following condition:
0.6<|f12w|/f34w <0.8
wherein
f12w designates the combined focal length of the positive first lens group and the negative second lens group at the short focal length extremity; and
f34w designates the combined focal length of said positive third lens group and said positive fourth lens group at the short focal length extremity.

### Claim 19

A standard zoom lens system comprises a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group, in this order from an object,
wherein upon zooming from the short focal length extremity to the long focal length extremity, said positive first lens group, said positive third lens group and said positive fourth lens group move toward the object, and said negative second lens group moves toward an image and thereafter moves toward the object;
wherein said positive first lens group comprises a negative lens element and a positive lens element;
wherein said positive third lens group comprises a positive lens element, and cemented lens elements having a positive lens element and a negative lens element; and
wherein said standard zoom lens system satisfies the following conditions:
7.5<f1/|f2|<9.5
3.0<f1/f3 <5.0
wherein
f1 designates the focal length of said positive first lens group;
f2 designates the focal length of said negative second lens group; and
f3 designates the focal length of said positive third lens group.