Zoom lens system

Patent metadata

Field	Value
Publication number	US-9146389-B2
Application number	US-201313955666-A
Country	US
Kind code	B2
Filing date	Jul 31, 2013
Priority date	Jan 11, 2013
Publication date	Sep 29, 2015
Grant date	Sep 29, 2015

Abstract

A zoom lens system that includes a first lens group including at least one lens and having a negative refractive power, and a second lens group including at least one lens and having a positive refractive power in an order from an object side to an image side, wherein the zoom lens system is configured to perform zooming by changing a distance between the first lens group and the second lens group and satisfies: 2<|f 1 /fw|<2.5 and 0.60<|f 1 /f 2 |<0.85, wherein f 1 indicates a synthetic focal length of the first lens group, fw indicates an overall focal length at a wide angle end, and f 2 indicates a synthetic focal length of the second lens group.

First claim

What is claimed is:

1. A zoom lens system comprising, in an order from an object side to an image side:
a first lens group comprising at least one lens and having a negative refractive power; and
a second lens group comprising at least one lens and having a positive refractive power,
wherein the zoom lens system is configured to perform zooming by changing a distance between the first lens group and the second lens group and satisfies:
2 <|f 1 /fw |<2.5, and
0.60 <|f 1 /f 2|<0.85,

wherein f 1 indicates a synthetic focal length of the first lens group, fw indicates an overall focal length at a wide angle end, and f 2 indicates a synthetic focal length of the second lens group,
wherein the zoom lens system has only two lens groups,
wherein a number of lenses included in the first lens group is three.

2. The zoom lens system of claim 1 , wherein a total length of the zoom lens system satisfies:
Tw/D <13.5,
wherein Tw indicates the total length of the zoom lens system at the wide angle end, and D indicates a diagonal length of an image surface passing a center of the image surface.

3. The zoom lens system of claim 1 , wherein a lens disposed second closest to the object side among the at least one lens of the first lens group satisfies:
Vd12<55,
wherein Vd 12 indicates an Abbe number at a d line of the lens disposed second closest to the object side among the at least one lens of the first lens group.

4. The zoom lens system of claim 1 , wherein a lens disposed third closest to the object side among the at least one lens of the first lens group satisfies:
Nd13>1.90,
wherein Nd 13 indicates a refractive index at a d line of the lens disposed third closest to the object side among the at least one lens of the first lens group.

5. The zoom lens system of claim 1 , wherein lenses disposed second and third closest to the object side among the at least one lens of the first lens group form a cemented lens.

6. The zoom lens system of claim 1 , wherein a lens disposed first closest to the object side among the at least one lens of the second lens group satisfies:
Vd24>60,
wherein Vd 24 indicates an Abbe number at a d line of the lens disposed first closest to the object side among the lenses of the second lens group.

7. The zoom lens system of claim 1 , wherein lenses disposed third and fourth closest to the object side among the at least one lens of the second lens group satisfy:
Vd26<35, and
Vd27>75,
wherein Vd 26 indicates an Abbe number at a d line of a lens disposed third closest to the object side among the at least one lens of the second lens group, and Vd 27 indicates an Abbe number at the d line of a lens disposed fourth closest to the object side among the at least one lens of the second lens group.

8. The zoom lens system of claim 7 , wherein the lenses disposed third and fourth closest to the object side among the lenses of the second lens group form a cemented lens.

9. The zoom lens system of claim 1 , wherein the first lens group comprises a negative lens, a negative lens, and a positive lens in the order from the object side to the image side.

10. The zoom lens system of claim 1 , wherein the second lens group comprises a positive lens, a positive lens, a negative lens, a positive lens, and a positive lens in the order from the object side to the image side.

11. The zoom lens system of claim 1 , wherein a lens disposed closest to the object side among the at least one lens of the second lens group comprises at least one aspherical surface.

12. The zoom lens system of claim 1 , wherein a lens disposed closest to the image side among the at least one lens of the second lens group comprises at least one aspherical surface.

13. The zoom lens system of claim 1 , further comprising an aperture disposed between the first lens group and the second lens group, and a near infrared ray blocking filter disposed on or adjacent to a surface of the aperture facing the image side.

14. A zoom lens system comprising:
a first lens group comprising at least one lens and having a negative refractive power; and
a second lens group comprising at least one lens and having a positive refractive power,
wherein the zoom lens system is configured to perform zooming by changing a distance between the first lens group and the second lens group, and satisfies;
2 <|f 1 /fw |<2.5, and
2.8 <|f 2 /fw |<3.2,

wherein f 1 indicates a synthetic focal length of the first lens group, fw indicates an overall focal length at a wide angle end, and f 2 indicates a synthetic focal length of the second lens group,
wherein the zoom lens system has only two lens groups,
wherein a number of lenses included in the first lens group is three.

15. The zoom lens system of claim 14 , wherein the zoom lens system satisfies:
0.60 <|f 1 /f 2|<0.85.

16. The zoom lens system of claim 14 , wherein a total length of the zoom lens system satisfies:
Tw/D< 13.5,
wherein Tw indicates the total length of the zoom lens system at a wide angle end, and D indicates a diagonal length of an image surface passing a center of the image surface.

17. The zoom lens system of claim 14 , wherein lenses disposed second and third closest to the object side among at least one lens of the first lens group form a cemented lens, and the lenses satisfy:
Vd12<55, and
Nd13>1.90,
wherein Vd 12 indicates an Abbe number at a d line of a lens disposed second closest to the object side of the first lens group, and Nd 13 indicates a refractive index at a d line of a lens disposed third closest to the object side of the first lens group.

18. The zoom lens system of claim 14 , wherein a lens disposed closest to the object side among the at least one lens of the second lens group satisfies:
Vd24>60,
wherein Vd 24 indicates an Abbe number at a d line of the lens disposed closest to the object side among the at least one lens of the second lens group.

19. The zoom lens system of claim 14 , wherein lenses disposed third and fourth closest to the object side among the at least one lens of the second lens group satisfy:
Vd26<35, and
Vd27>75,
where Vd 26 indicates an Abbe number at a d line of the lens disposed third closest to the object side among the at least one lens of the second lens group, and Vd 27 indicates an Abbe number at the d line of the lens disposed fourth closest to the object side among the at least one lens of the second lens group.

Assignees

• Hanwha Techwin Co Ltd

Inventors

• Han Hee-Joong

Classifications

• G02B15/177 Primary

  having a negative front lens or group of lenses · CPC title

• G02B3/04

  with continuous faces that are rotationally symmetrical but deviate from a true sphere {, e.g. so called "aspheric" lenses} · CPC title

• G02B13/009

  having zoom function · CPC title

• G02B3/0062

  Stacked lens arrays, i.e. refractive surfaces arranged in at least two planes, without structurally separate optical elements in-between · CPC title

• G02B3/0087

  with index gradient · CPC title