Imaging lens and imaging apparatus including the same

Patent metadata

Field	Value
Publication number	US-9575289-B2
Application number	US-201414474693-A
Country	US
Kind code	B2
Filing date	Sep 2, 2014
Priority date	Aug 30, 2013
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

The imaging lens substantially consists of a first lens having a biconvex shape, a second lens having a negative refractive power, a third lens having a negative refractive power and a convex surface that faces the object side, a fourth lens having a positive refractive power, and a fifth lens having a negative refractive power, of which at least one of the object-side surface and the image-side surface has at least one inflection point, in this order from the object side; and wherein conditional expression (1A): −0.38<f/f45<−0.01 is satisfied. This conditional expression is related to the focal length f of the entire system and the combined focal length f45 of the fourth lens and the fifth lens.

First claim

What is claimed is:

1. An imaging lens substantially consisting of five lenses, including:
a first lens of being a biconvex shape;
a second lens having a negative refractive power;
a third lens having a negative refractive power and a convex surface that faces the object side;
a fourth lens having a positive refractive power;
a fifth lens having a negative refractive power, of which at least one surface of an object-side surface and an image-side surface has at least one inflection point, in this order from the object side; and
wherein conditional expressions (1A) and (2) below are satisfied:
−0.38< f/f 45<−0.01  (1A), where

f: the focal length of the entire system, and
f45: the combined focal length of the fourth lens and the fifth lens, and
1.7<( R 2 f−R 2 r )/( R 2 f+R 2 r )  (2), where

R2f: the paraxial radius of curvature of the object-side surface of the second lens, and
R2r: the paraxial radius of curvature of the image-side surface of the second lens.

2. The imaging lens of claim 1 , wherein the fifth lens is of a biconcave shape.

3. The imaging lens of claim 1 , wherein conditional expression below is further satisfied:
−0.27< f/f 45<−0.015  (1A-1).

4. The imaging lens of claim 1 , wherein conditional expression is further satisfied:
−0.25< f/f 45<−0.02  (1 A -2).

5. The imaging lens of claim 1 , wherein the second lens is of a biconcave shape.

6. The imaging lens of claim 1 , wherein the fourth lens is of a meniscus shape having a convex surface that faces the image side.

7. The imaging lens of claim 1 , wherein an aperture stop is provided between the object-side surface of the first lens L1 and the object-side surface of the second lens L2.

8. The imaging lens of claim 1 , wherein conditional expression below is further satisfied:
0< f/f 4<1.9  (3), where

f4: the focal length of the fourth lens.

9. The imaging lens of claim 1 , wherein conditional expression below is further satisfied:
1.7<( R 2 f−R 2 r )/( R 2 f+R 2 r )<4  (2-1), where

R2f: the paraxial radius of curvature of the object-side surface of the second lens, and
R2r: the paraxial radius of curvature of the image-side surface of the second lens.

10. The imaging lens of claim 1 , wherein conditional expression below is further satisfied:
1.8<( R 2 f−R 2 r )/( R 2 f+R 2 r )<3.5  (2-2), where

R2f: the paraxial radius of curvature of the object-side surface of the second lens, and
R2r: the paraxial radius of curvature of the image-side surface of the second lens.

11. The imaging lens of claim 1 , wherein conditional expression below is further satisfied:
0< f/f 4<1.8  (3-1), where

f4: the focal length of the fourth lens.

12. The imaging lens of claim 1 , wherein conditional expression below is further satisfied:
0< f/f 4<1.75  (3-2), where

f4: the focal length of the fourth lens.

13. An imaging apparatus, including the imaging lens of claim 1 .

14. The imaging lens substantially consisting of five lenses, including:
a first lens of being a biconvex shape;
a second lens having a negative refractive power;
a third lens having a negative refractive power and a convex surface that faces the object side;
a fourth lens having a positive refractive power;
a fifth lens having a biconcave shape, of which at least one surface of an object-side surface and an image-side surface has at least one inflection point, in this order from the object side; and
wherein conditional expressions (1B) and (2) below are satisfied:
f/f 45<0  (1B), where

f: the focal length of the entire system, and
f45: the combined focal length of the fourth lens and the fifth lens, and
1.7<( R 2 f−R 2 r )/( R 2 f+R 2 r )  (2), where

R2f: the paraxial radius of curvature of the object-side surface of the second lens, and
R2r: the paraxial radius of curvature of the image-side surface of the second lens.

15. The imaging lens of claim 14 , wherein conditional expression below is further satisfied:
−2< f/f 45<0  (1B-1).

16. The imaging lens of claim 14 , wherein conditional expression below is further satisfied:
−1< f/f 45<0  (1B-2).

17. An imaging apparatus, including: The the imaging lens of claim 14 .

Assignees

• Fujifilm Corp

Inventors

• Nishihata Sumihiro
• Ishii Yoshiaki

Classifications

• G02B13/0045 Primary

  having five or more lenses · CPC title