Imaging lens
An imaging lens which uses a larger number of constituent lenses for higher performance and features a low F-value, low-profile design and a wide field of view. Designed for a solid-state image sensor, the imaging lens includes constituent lenses arranged in order from an object side to an image side: a first positive refractive power lens; a second negative refractive power lens; a third lens; a fourth lens; a fifth lens; a sixth lens having a concave image-side surface near an optical axis; and a seventh negative refractive power lens.
1. An imaging lens in which elements are arranged in order from an object side to an image side, comprising:
a first lens with positive refractive power;
a second lens with negative refractive power;
a third lens;
a fourth lens;
a fifth lens;
a sixth lens having a concave surface on the image side near an optical axis; and
a seventh lens with negative refractive power.
2. The imaging lens according to claim 1 ,
wherein the first lens has a convex surface on the object side near the optical axis, and the second lens has a concave surface on the image side near the optical axis.
3. The imaging lens according to claim 1 ,
wherein the third lens has positive refractive power with a convex surface facing the image side near the optical axis, and the fourth lens has negative refractive power with a concave surface facing the image side near the optical axis.
4. The imaging lens according to claim 1 ,
wherein the fifth lens is a meniscus lens with positive refractive power having a convex surface on the image side near the optical axis.
5. The imaging lens according to claim 1 ,
wherein the sixth lens is a meniscus double-sided aspheric lens, having a pole-change point in a position off the optical axis on the object-side surface and the image-side surface thereof, and the seventh lens is a double-sided aspheric lens with a concave surface facing the image side near the optical axis, having a pole-change point in a position off the optical axis on the image-side surface thereof.
6. The imaging lens according to claim 1 ,
wherein conditional expressions (1) and (2) below are satisfied;
50<ν d 1<70 (1)
20<ν d 2<30 (2)
where
νd1; Abbe number of the first lens at d-ray, and
νd2: Abbe number of the second lens at d-ray.
7. The imaging lens according to claim 1 ,
wherein conditional expressions (3) and (4) below are satisfied;
50<ν d 3<70 (3)
20<ν d 4<30 (4)
where
νd3: Abbe number of the third lens at d-ray, and
νd4: Abbe number of the fourth lens at d-ray.
8. The imaging lens according to claim 1 ,
wherein a conditional expression (5) below is satisfied;
0.6< TTL/ 2 ih< 1.0 (5)
where
TTL: distance on the optical axis from an object-side surface of an optical element located nearest to an object to an image plane without a filter or the like, and
ih: maximum image height.
9. The imaging lens according to claim 1 ,
wherein a conditional expression (6) below is satisfied;
0.85<Σ d/f< 1.25 (6)
where
f: focal length of an overall optical system of the imaging lens, and
Σd: distance on the optical axis from the object-side surface of the first lens to the image-side surface of the seventh lens.
10. The imaging lens according to claim 1 ,
wherein a conditional expression (7) below is satisfied;
0.8< ih/f< 1.2 (7)
where
f: focal length of an overall optical system of the imaging lens, and
ih: maximum image height.
11. The imaging lens according to claim 1 ,
wherein conditional expressions (8) and (9) below are satisfied;
0.7< f 1/ f< 1.5 (8)
−5.0< f 2/ f<− 1.0 (9)
where
f: focal length of an overall optical system of the imaging lens,
f1: focal length of the first lens, and
f2: focal length of the second lens.
12. The imaging lens according to claim 1 ,
wherein a conditional expression (10) below is satisfied;
2.0<| f 34/ f| (10)
where
f: focal length of an overall optical system of the imaging lens, and
f34: composite focal length of the third lens and the fourth lens.
13. The imaging lens according to claim 1 ,
wherein conditional expressions (11) and (12) below are satisfied;
0.6< f 5/ f< 1.2 (11)
−1.2< f 67/ f<− 0.6 (12)
where
f: focal length of an overall optical system of the imaging lens,
f5: focal length of the fifth lens, and
f67: composite focal length of the sixth lens and the seventh lens.
14. The imaging lens according to claim 1 ,
wherein conditional expressions (13), (14), and (15) below are satisfied;
50<ν d 5<70 (13)
20<ν d 6<30 (14)
50<ν d 7<70 (15)
where
νd5: Abbe number of the fifth lens at d-ray,
νd6: Abbe number of the sixth lens at d-ray, and
νd7: Abbe number of the seventh lens at d-ray.
15. An imaging lens in which elements are arranged in order from an object side to an image side, comprising:
a first lens with positive refractive power having a biconvex shape near an optical axis;
a second lens;
a third lens;
a fourth lens;
a fifth lens;
a sixth lens as a double-sided aspheric lens having a convex surface on the object side near the optical axis; and
a seventh lens with negative refractive power as a meniscus double-sided aspheric lens;
wherein a conditional expression (10) below is satisfied;
2.0<| f 34/ f| (10)
where
f: focal length of an overall optical system of the imaging lens, and
f34: composite focal length of the third lens and the fourth lens.
16. The imaging lens according to claim 15 ,
wherein the second lens has negative refractive power with a concave surface facing the image side near the optical axis.
17. The imaging lens according to claim 15 ,
wherein the third lens has positive refractive power with a convex surface facing the image side near the optical axis, and the fourth lens has negative refractive power with a concave surface facing the image side near the optical axis.
18. The imaging lens according to claim 15 ,
wherein the fifth lens is a meniscus lens with positive refractive power having a convex surface on the image side near the optical axis.
19. The imaging lens according to claim 15 ,
wherein the sixth lens is a meniscus lens, having a pole-change point in a position off the optical axis on the object-side surface and the image-side surface thereof, and the seventh lens has a concave surface on the image side near the optical axis, having a pole-change point in a position off the optical axis on the image-side surface thereof.
20. The imaging lens according to claim 15 ,
wherein a conditional expression (5) below is satisfied;
0.6< TTL/ 2 ih< 1.0 (5)
where
TTL: distance on the optical axis from an object-side surface of an optical element located nearest to an object to an image plane without a filter or the like, and
ih: maximum image height.