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, comprising in order from an object side to an image side thereof:
a first lens with positive refractive power;
a second lens having an aspheric surface;
a third lens having an aspheric surface;
a fourth lens having an aspheric surface;
a fifth lens having positive refractive power and an aspheric surface;
a sixth lens that is a double-sided aspheric lens;
a seventh lens that is a double-sided aspheric lens having negative refractive power, an image-side surface of the seventh lens having a pole-change point separated from an optical axis of the imaging lens;
wherein the lenses are each arranged with an air gap therebetween, and a conditional expression (2) below is satisfied:
20<ν d 2<30 (2)
where
νd2: Abbe number of the second lens at d-ray.
2. The imaging lens according to claim 1 , wherein conditional expressions (1) and (3) below are satisfied:
50<ν d 1<70 (1)
50<ν d 3<70 (3)
where
νd1: Abbe number of the first lens at d-ray, and
νd3: Abbe number of the third lens at d-ray.
3. The imaging lens according to claim 1 ,
wherein the first lens has a convex surface facing the object side near the optical axis,
the second lens has negative refractive power and a concave surface facing the image side near the optical axis,
the third lens has positive refractive power and a convex surface facing the image side near the optical axis,
the fourth lens has negative refractive power and a concave surface facing the image side near the optical axis, and
the fifth lens has a convex surface facing the image side near the optical axis.
4. The imaging lens according to claim 1 , wherein the sixth lens has negative refractive power and a concave surface facing the image side near the optical axis.
5. The imaging lens according to claim 1 , wherein conditional expressions (5) and (6) below are satisfied:
0.6< TTL/ 2 ih< 1.0 (5)
0.85<Σ d/f< 1.25 (6)
where
TTL: distance along the optical axis from an image plane of the imaging lens to an object-side surface of an optical element located nearest an imaged object,
ih: maximum image height,
f: overall focal length of the imaging lens, and
Σd: distance along the optical axis from an object-side surface of the first lens to an image-side surface of the seventh lens.
6. The imaging lens according to claim 1 , wherein a conditional expression (7) below is satisfied:
0.8< ih/f< 1.2 (7)
where
f: overall focal length of the imaging lens, and
ih: maximum image height.
7. 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: overall focal length of the imaging lens,
f1: focal length of the first lens, and
f2: focal length of the second lens.
8. An imaging lens, comprising in order from an object side to an image side thereof:
a first lens with positive refractive power;
a second lens having an aspheric surface;
a third lens that is a meniscus lens having an aspheric surface;
a fourth lens having an aspheric surface;
a fifth lens having an aspheric surface;
a sixth lens that is a double-sided aspheric lens having a concave surface facing the image side near an optical axis of the imaging lens; and
a seventh lens that is a meniscus double-sided aspheric lens;
wherein the lenses are each arranged with an air gap therebetween, and a conditional expression (5) below is satisfied:
0.6< TTL/ 2 ih< 1.0 (5)
where
TTL: distance along the optical axis from an image plane of the imaging lens to an object-side surface of an optical element located nearest an imaged object,
ih: maximum image height.
9. The imaging lens according to claim 8 , wherein conditional expressions (1), (2), and (3) below are satisfied:
50<ν d 1<70 (1)
20<ν d 2<30 (2)
50<ν d 3<70 (3)
where
νd1: Abbe number of the first lens at d-ray,
νd2: Abbe number of the second lens at d-ray, and
νd3: Abbe number of the third lens at d-ray.
10. The imaging lens according to claim 8 ,
wherein the first lens has a convex surface facing the object side near the optical axis,
the second lens has negative refractive power and a concave surface facing the image side near the optical axis,
the third lens has positive refractive power and a convex surface facing the image side near the optical axis,
the fourth lens has negative refractive power and a concave surface facing the image side near the optical axis, and
the fifth lens has positive refractive power and a convex surface facing the image side near the optical axis.
11. The imaging lens according to claim 8 ,
wherein the sixth lens has negative refractive power, and
the seventh lens has negative refractive power and a concave surface facing the image side near the optical axis and a pole-change point separated from the optical axis.
12. The imaging lens according to claim 8 , wherein conditional expression and (6) below is satisfied:
0.85<Σ d/f< 1.25 (6)
where
f: overall focal length of the imaging lens, and
Σd: distance along the optical axis from an object-side surface of the first lens to an image-side surface of the seventh lens.
13. The imaging lens according to claim 8 , wherein a conditional expression (7) below is satisfied:
0.8< ih/f< 1.2 (7)
where
f: overall focal length of the imaging lens.
14. The imaging lens according to claim 8 , 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: overall focal length of the imaging lens,
f1: focal length of the first lens, and
f2: focal length of the second lens.
15. An imaging lens, comprising in order from an object side to an image side of the imaging lens:
a first lens with positive refractive power;
a second lens having an aspheric surface;
a third lens having an aspheric surface;
a fourth lens having an aspheric surface;
a fifth lens having an aspheric surface;
a sixth lens that is a double-sided aspheric lens having negative refractive power, an image-side surface of the sixth lens having a pole-change point separated from an optical axis of the imaging lens; and
a seventh lens that is a double-sided aspheric lens, having a concave surface facing the image side near the optical axis and a pole-change point separated from the optical axis,
wherein the lenses are each arranged with an air gap therebetween, and a conditional expression (6) below is satisfied:
0.85<Σ d/f< 1.25 (6)
where
f: overall focal length of the imaging lens, and
Σd: distance along the optical axis from an object-side surface of the first lens to an image-side surface of the seventh lens.
16. The imaging lens according to claim 15 , 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.
17. The imaging lens according to claim 15 ,
wherein the first lens has a convex surface facing the object side near the optical axis,
the second lens has negative refractive power and a concave surface facing the image side near the optical axis,
the third lens has positive refractive power and a convex surface facing the image side near the optical axis,
the fourth lens has negative refractive power and a concave surface facing the image side near the optical axis, and
the fifth lens has positive refractive power and a convex surface facing the image side near the optical axis.
18. The imaging lens according to claim 15 ,
wherein the sixth lens has a concave surface facing the image side near the optical axis, and
the seventh lens has negative refractive power.
19. The imaging lens according to claim 15 , wherein a conditional expressions (5) below is satisfied:
0.6< TTL/ 2 ih< 1.0 (5)
where
TTL: distance along the optical axis from an image plane of the imaging lens to an object-side surface of an optical element located nearest an imaged object, and
ih: maximum image height.