Imaging lens and imaging apparatus
An imaging lens is provided and includes: in order from the object side, a negative first lens, a negative second lens, a positive third lens, a stop, and a positive fourth lens. In the lens, each of the second lens, the third lens, and the fourth lens has at least one aspheric surface, and an Abbe number of a material of the third lens at the d-line is 35 or less. In addition, the imaging lens satisfies the following Conditional Expression (1): −0.2<( R 3+ R 4)/( R 3− R 4)<0.2 (1) where R 3 is a paraxial radius of curvature of the object side surface of the second lens, and R 4 is a paraxial radius of curvature of the image side surface of the second lens.
1. An imaging lens comprising: in order from an object side thereof,
a negative first lens;
a negative second lens;
a positive third lens;
a stop; and
a positive fourth lens,
wherein
each of the second lens, the third lens, and the fourth lens has at least one aspheric surface,
an Abbe number of a material of the third lens at the d-line is 35 or less, and
the following Conditional Expression (1) is satisfied:
−0.2<( R 3+ R 4)/( R 3− R 4)<0.2 (1)
wherein R 3 is a paraxial radius of curvature of an object side surface of the second lens, and R 4 is a paraxial radius of curvature of an image side surface of the second lens.
2. The imaging lens according to claim 1 , wherein the following Conditional Expression (5) is satisfied:
2.0 <D 2/ f< 5.0 (5)
wherein f is the focal length of the imaging lens, and D 2 is an air space on an optical axis between the first lens and the second lens.
3. The imaging lens according to clam 1 , wherein the following Conditional Expression (6) is satisfied:
0.01<| f 12/ f 34|<0.5 (6)
wherein f 12 is a composite focal length of the first lens and the second lens, and f 34 is a composite focal length of the third lens and the fourth lens.
4. The imaging lens according to claim 1 , wherein the following Conditional Expression (7) is satisfied:
2.5<( D 4+ D 5)/ f< 5.5 (7)
wherein f is the focal length of the imaging lens, D 4 is an air space on the optical axis between the second lens and the third lens, and D 5 is a center thickness of the third lens.
5. The imaging lens according to claim 1 , wherein the following Conditional Expression (8) is satisfied:
10.0< L/f< 20.0 (8)
wherein f is the focal length of the imaging lens, and L is a distance on the optical axis from the object side surface of the first lens to an image plane.
6. The imaging lens according to claim 1 , wherein the following Conditional Expression (9) is satisfied:
1.5< Bf/f< 4.0 (9)
where
f is the focal length of the lens system, and
Bf is a distance on the optical axis from the image side surface of the fourth lens to the image plane.
7. The imaging lens according to claim 1 , wherein the following Conditional Expression (10) is satisfied:
0.3<( R 8− R 9)/( R 8+ R 9)<1.0 (10)
wherein R 8 is a paraxial radius of curvature of an object side surface of the fourth lens, and R 9 is a paraxial radius of curvature of the image side surface of the fourth lens.
8. An imaging apparatus comprising an imaging lens according to claim 1 .
9. An imaging lens comprising: in order from an object side thereof,
a negative first lens which has a meniscus shape concave toward the image side;
a second lens of which an object side surface and an image side surface are aspheric;
a positive third lens of which an object side surface is aspheric;
a stop; and
a positive fourth lens of which an image side surface is aspheric, wherein
an Abbe number of a material of the third lens at the d-line is 35 or less, and
the following Conditional Expression (2) is satisfied:
1.0< D 3/ f< 5.0 (2)
wherein D 3 is a center thickness of the second lens, and f is a focal length of the whole system.
10. The imaging lens according to claim 9 , wherein the following Conditional Expression (5) is satisfied:
2.0< D 2/ f< 5.0 (5)
wherein f is the focal length of the imaging lens, and D 2 is an air space on an optical axis between the first lens and the second lens.
11. The imaging lens according to claim 9 , wherein the following Conditional Expression (6) is satisfied:
0.01<| f 12/ f 34|<0.5 (6)
wherein f 12 is a composite focal length of the first lens and the second lens, and f 34 is a composite focal length of the third lens and the fourth lens.
12. The imaging lens according to claim 9 , wherein the following Conditional Expression (7) is satisfied:
2.5<( D 4+ D 5)/ f< 5.5 (7)
wherein f is the focal length of the imaging lens, D 4 is an air space on the optical axis between the second lens and the third lens, and D 5 is a center thickness of the third lens.
13. The imaging lens according to claim 9 , wherein the following Conditional Expression (8) is satisfied:
10.0< L/f< 20.0 (8)
wherein f is the focal length of the imaging lens, and L is a distance on the optical axis from the object side surface of the first lens to an image plane.
14. The imaging lens according to claim 9 , wherein the following Conditional Expression (9) is satisfied:
1.5< Bf/f< 4.0 (9)
where
f is the focal length of the lens system, and
Bf is a distance on the optical axis from the image side surface of the fourth lens to the image plane.
15. The imaging lens according to claim 9 , wherein the following Conditional Expression (10) is satisfied:
0.3<( R 8− R 9)/( R 8+ R 9)<1.0 (10)
wherein R 8 is a paraxial radius of curvature of an object side surface of the fourth lens, and R 9 is a paraxial radius of curvature of the image side surface of the fourth lens.
16. An imaging apparatus comprising an imaging lens according to claim 9 .
17. An imaging lens comprising: in order from an object side thereof,
a negative first lens;
a negative second lens;
a positive third lens;
a stop; and
a positive fourth lens,
wherein
a center thickness of the first lens is 1.7 mm or more, and
the following Conditional Expression (3) is satisfied:
2.5< D 1/ f< 5.5 (3)
wherein D 1 is the center thickness of the first lens, and f is a focal length of the imaging lens.
18. The imaging lens according to claim 17 , wherein the following Conditional Expression (5) is satisfied:
2.0< D 2/ f< 5.0 (5)
wherein f is the focal length of the imaging lens, and D 2 is an air space on an optical axis between the first lens and the second lens.
19. The imaging lens according to clam 17 , wherein the following Conditional Expression (6) is satisfied:
0.01<| f 12/ f 34|<0.5 (6)
wherein f 12 is a composite focal length of the first lens and the second lens, and f 34 is a composite focal length of the third lens and the fourth lens.
20. The imaging lens according to claim 17 , wherein the following Conditional Expression (7) is satisfied:
2.5<( D 4+ D 5)/ f< 5.5 (7)
wherein f is the focal length of the imaging lens, D 4 is an air space on the optical axis between the second lens and the third lens, and D 5 is a center thickness of the third lens.
21. The imaging lens according to claim 17 , wherein the following Conditional Expression (8) is satisfied:
10.0< L/f< 20.0 (8)
wherein f is the focal length of the imaging lens, and L is a distance on the optical axis from the object side surface of the first lens to an image plane.
22. The imaging lens according to claim 17 , wherein the following Conditional Expression (9) is satisfied:
1.5< Bf/f< 4.0 (9)
where
f is the focal length of the lens system, and
Bf is a distance on the optical axis from the image side surface of the fourth lens to the image plane.
23. The imaging lens according to claim 17 , wherein the following Conditional Expression (10) is satisfied:
0.3<( R 8− R 9)/( R 8+ R 9)<1.0 (10)
wherein R 8 is a paraxial radius of curvature of an object side surface of the fourth lens, and R 9 is a paraxial radius of curvature of the image side surface of the fourth lens.
24. An imaging apparatus comprising an imaging lens according to claim 17 .
25. An imaging lens comprising: in order from an object side thereof,
a negative first lens;
a negative second lens;
a positive third lens;
a stop; and
a positive fourth lens,
wherein
a center thickness of the first lens is 1.7 mm or more, and the following Conditional Expression (4) is satisfied:
0.5< ED 1/ R 1<0.95 (4)
wherein ED 1 is an effective diameter of an object side surface of the first lens, and R 1 is a radius of curvature of the object side surface of the first lens.
26. The imaging lens according to claim 25 , wherein the following Conditional Expression (5) is satisfied:
2.0< D 2/ f< 5.0 (5)
wherein f is the focal length of the imaging lens, and D 2 is an air space on an optical axis between the first lens and the second lens.
27. The imaging lens according to clam 25 , wherein the following Conditional Expression (6) is satisfied:
0.01<| f 12/ f 34|<0.5 (6)
wherein f 12 is a composite focal length of the first lens and the second lens, and f 34 is a composite focal length of the third lens and the fourth lens.
28. The imaging lens according to claim 25 , wherein the following Conditional Expression (7) is satisfied:
2.5<( D 4+ D 5)/f<5.5 (7)
wherein f is the focal length of the imaging lens, D 4 is an air space on the optical axis between the second lens and the third lens, and D 5 is a center thickness of the third lens.
29. The imaging lens according to claim 25 , wherein the following Conditional Expression (8) is satisfied:
10.0< L/f< 20.0 (8)
wherein f is the focal length of the imaging lens, and L is a distance on the optical axis from the object side surface of the first lens to an image plane.
30. The imaging lens according to claim 25 , wherein the following Conditional Expression (9) is satisfied:
1.5< Bf/f< 4.0 (9)
where
f is the focal length of the lens system, and
Bf is a distance on the optical axis from the image side surface of the fourth lens to the image plane.
31. The imaging lens according to claim 25 , wherein the following Conditional Expression (10) is satisfied:
0.3<( R 8− R 9)/( R 8+ R 9)<1.0 (10)
wherein R 8 is a paraxial radius of curvature of an object side surface of the fourth lens, and R 9 is a paraxial radius of curvature of the image side surface of the fourth lens.
32. An imaging apparatus comprising an imaging lens according to claim 25 .