Imaging lens and imaging apparatus including the imaging lens

Patent metadata

Field	Value
Publication number	US-9235029-B2
Application number	US-201414220157-A
Country	US
Kind code	B2
Filing date	Mar 20, 2014
Priority date	Mar 29, 2013
Publication date	Jan 12, 2016
Grant date	Jan 12, 2016

Abstract

An imaging lens substantially consists of, in order from an object side, five lenses of a first lens that has a positive refractive power and has a meniscus shape which is convex toward the object side, a second lens that has a negative refractive power and has a meniscus shape which is concave toward the object side, a third lens that has a meniscus shape which is convex toward the image side, a fourth lens that has a positive refractive power and is convex toward the object side, and a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface.

First claim

What is claimed is:

1. An imaging lens consisting of, in order from an object side, five lenses of:
a first lens that has a positive refractive power and has a meniscus shape which is convex toward the object side;
a second lens that has a negative refractive power and has a meniscus shape which is concave toward the object side;
a third lens that has a meniscus shape which is convex toward the image side;
a fourth lens that has a positive refractive power and is convex toward the object side; and
a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface.

2. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−2< f/f 345<−0.25  (1), where

f is a focal length of a whole system, and
f345 is a composite focal length of the third to fifth lenses.

3. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.2<( R 4 f+R 3 r )/( R 4 f−R 3 r )<1.6  (2), where

R3r is a paraxial radius of curvature of an image side surface of the third lens, and
R4f is a paraxial radius of curvature of an object side surface of the fourth lens.

4. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.5< f 1/ f 3<1  (3), where

f1 is a focal length of the first lens, and
f3 is a focal length of the third lens.

5. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.5<( R 3 f−R 3 r )/( R 3 f+R 3 r )<0.3  (4), where

R3f is a paraxial radius of curvature of an object side surface of the third lens, and
R3r is a paraxial radius of curvature of the image side surface of the third lens.

6. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.5< f ·tan ω/ R 5 r< 10  (5), where

f is a focal length of a whole system,
ω is a half angle of view, and
R5r is a paraxial radius of curvature of the image side surface of the fifth lens.

7. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−2< f/f 5<−0.2  (6), where

f is a focal length of a whole system, and
f5 is a focal length of the fifth lens.

8. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.8< f/f 1<2.5  (7), where

f is a focal length of a whole system, and
f1 is a focal length of the first lens.

9. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.8< f/f 3<0.3  (8), where

f is a focal length of a whole system, and
f3 is a focal length of the third lens.

10. The imaging lens, as defined in claim 1 , further comprising an aperture stop that is disposed on the object side of an object side surface of the second lens.

11. The imaging lens, as defined in claim 1 , wherein the third lens has a positive refractive power.

12. The imaging lens, as defined in claim 1 , wherein the third lens has a negative refractive power.

13. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−1.8< f/f 345<−0.3  (1-1), where

f is a focal length of a whole system, and
f345 is a composite focal length of the third to fifth lenses.

14. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.25<( R 4 f+R 3 r )/( R 4 f−R 3 r )<1.3  (2-1), where

R3r is a paraxial radius of curvature of the image side surface of the third lens, and
R4f is a paraxial radius of curvature of the object side surface of the fourth lens.

15. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.4< f 1/ f 3<0.3  (3-1), where

f1 is a focal length of the first lens, and
f3 is a focal length of the third lens.

16. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.4<( R 3 f−R 3 r )/( R 3 f+R 3 r )<0.15  (4-1), where

R3f is a paraxial radius of curvature of the object side surface of the third lens, and
R3r is a paraxial radius of curvature of the image side surface of the third lens.

17. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.7< f ·tan ω/ R 5 r< 3  (5-1), where

f is a focal length of a whole system,
ω is a half angle of view, and
R5r is a paraxial radius of curvature of the image side surface of the fifth lens.

18. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−1.5 <f/f 5<−0.4  (6-1), where

f is a focal length of a whole system, and
f5 is a focal length of the fifth lens.

19. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
1< f/f 1<2  (7-1), where

f is a focal length of a whole system, and
f1 is a focal length of the first lens.

20. An imaging apparatus comprising:
the imaging lens, as defined in claim 1 .

Assignees

• Fujifilm Corp

Inventors

• Noda Takayuki
• Cho Michio

Classifications

• G02B13/0045 Primary

  having five or more lenses · CPC title

• G02B9/60

  having five components only · CPC title