Telephoto lens

• US 10,151,903 B2
• Filed: 05/20/2016
• Issued: 12/11/2018
• Est. Priority Date: 03/23/2016
• Status: Active Grant

• Current Assignee: Zhejiang Sunny Optics Company Limited (Sunny Optical Technology (Group) Co., Ltd.)
• Original Assignee: Zhejiang Sunny Optics Company Limited (Sunny Optical Technology (Group) Co., Ltd.)
• Inventors: Huang, Lin, Lin, Faguan
• Primary Examiner(s): Choi, William
• Application Number:
  US15/542,435
• Publication Number:
  US 20180045923A1
• Time in Patent Office: 935 Days
• Field of Search: 359715, 359753, 359772-775
• CPC Class Codes: G02B 13/004 having four lenses
• CPC Class Codes: G02B 13/02 Telephoto objectives, i.e. systems of the type + - in which the distance from the front vertex to the image plane is less than the equivalent focal length
• CPC Class Codes: G02B 9/34 having four components only

Abstract

A telephoto lens includes, from an object-side to an image-side: a first lens having a positive refractive power, wherein an object-side surface of the first lens is convex, an image-side surface of the first lens is convex; a second lens having a refractive power; a third lens having a refractive power, wherein the third lens includes plastic material, each of an object-side and an image-side surface of the third lens is aspheric; a fourth lens having a refractive power, wherein an object-side surface of the fourth lens is convex, the fourth lens includes plastic material, and each of the object-side and image-side surfaces of the fourth lens is aspheric; wherein, the telephoto lens satisfies: 0.7<TTL/f<0.95, and |f4/f|≥1.2; where TTL is distance from the first lens'"'"' object-side surface to an imaging plane; f is effective focal length of the telephoto lens, and f4 is effective focal length of the fourth lens.

Claims

1. A telephoto lens, in sequence from an object side to an image side, comprising:

a first lens having a positive refractive power, wherein an object-side surface of the first lens is a convex surface, an image-side surface of the first lens is a convex surface;

a second lens having a refractive power;

a third lens having a refractive power, wherein the third lens is made of a plastic material, each of an object-side surface and an image-side surface of the third lens is an aspheric surface;

a fourth lens having a refractive power, wherein an object-side surface of the fourth lens is a convex surface, the fourth lens is made of a plastic material, and each of the object-side surface and an image-side surface of the fourth lens is an aspheric surface;

wherein, the telephoto lens satisfies the following relations;

0.7<

TTL/f<

0.95; and

|f4/f|≥

1.2;

wherein, TTL denotes a distance from the object-side surface of the first lens to an imaging plane along an axis;

f denotes an effective focal length of the telephoto lens, and f4 denotes an effective focal length of the fourth lens.

2. The telephoto lens according to claim 1, wherein the second lens has a negative refractive power, and the third lens has a negative refractive power.

3. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the following relation:

−

0.7≤

f1/f3<

0;

wherein, f1 denotes an effective focal length of the first lens, and f3 denotes an effective focal length of the third lens.

4. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the following relation:

2.5<

f1/CT1<

4.0;

wherein, f1 denotes the effective focal length of the first lens, and CT1 denotes a center thickness of the first lens.

5. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the following relation:

0.25≤

CT2/CT1<

0.5;

wherein, CT1 denotes the center thickness of the first lens, and CT2 denotes a center thickness of the second lens.

6. The telephoto lens according to claim 1, wherein the image-side surface of the third lens is a concave surface, the telephoto lens satisfies the following relation:

−

1.2<

SAG32/CT3<

0;

wherein, SAG32 denotes a sagitta of the image-side surface of the third lens, and CT3 denotes a center thickness of the third lens.

7. The telephoto lens according to claim 1, wherein the object-side surface of the fourth lens is a convex surface, the telephoto lens satisfies the following relation:

|SAG41/CT4|<

0.5;

wherein, SAG41 denotes a sagitta of the object-side surface of the fourth lens, and CT4 denotes a center thickness of the fourth lens.

8. The telephoto lens according to claim 1, wherein an image-side surface of the second lens is a concave surface, the telephoto lens satisfies the following relation:

0<

R1/R4<

1.0;

wherein, R1 denotes a radius of curvature of the object-side surface of the first lens, and R4 denotes a radius of curvature of the image-side surface of the second lens.

9. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the following relation:

|(R6+R7)/(R6−

R7)|≤

8;

wherein, R6 denotes a radius of curvature of the image-side surface of the third lens, and R7 denotes a radius of curvature of the object-side surface of the fourth lens.

10. The telephoto lens according to claim 1, wherein the telephoto lens satisfies the following relation:

TTL/ImgH≤

2.5;

wherein, ImgH denotes a half of a diagonal line of an effective pixel area in the imaging plane.