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 having a convex object-side surface; a second negative refractive power lens having a concave image-side surface; a third positive refractive power lens having a convex image-side surface; a fourth negative refractive power lens having a concave image-side surface; a fifth positive refractive power lens as a meniscus lens having a convex image-side surface; a sixth lens as a meniscus double-sided aspheric lens having a concave image-side surface near an optical axis; and a seventh negative refractive power lens as a double-sided aspheric lens having a concave image-side surface near the optical axis.
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 having a convex surface on the object side near an optical axis;
a second lens with negative refractive power having a concave surface on the image side near the optical axis;
a third lens with positive refractive power having a convex surface on the image side near the optical axis;
a fourth lens with negative refractive power having a concave surface on the image side near the optical axis;
a fifth lens with positive refractive power as a meniscus lens having a convex surface on the image side near the optical axis;
a sixth lens as a meniscus double-sided aspheric lens having a concave surface on the image side near the optical axis; and
a seventh lens with negative refractive power as a double-sided aspheric lens having a concave surface on the image side near the optical axis.
2. The imaging lens according to claim 1 ,
wherein conditional expressions (1) and (2) below are satisfied:
50<νd1<70 (1)
20<νd2<30 (2)
where
νd 1 : Abbe number of the first lens at d-ray
νd 2 : Abbe number of the second lens at d-ray.
3. The imaging lens according to claim 1 ,
wherein conditional expressions (3) and (4) below are satisfied:
50<νd3<70 (3)
20<νd4<30 (4)
where
νd 3 : Abbe number of the third lens at d-ray
νd 4 : Abbe number of the fourth lens at d-ray.
4. The imaging lens according to claim 1 ,
wherein an object-side surface and an image-side surface of the sixth lens are aspheric surfaces having a pole-change point in a position off the optical axis.
5. The imaging lens according to claim 1 ,
wherein an image-side surface of the seventh lens is an aspheric surface having a pole-change point in a position off the optical axis.
6. 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
ih: maximum image height.
7. The imaging lens according to claim 1 ,
wherein a conditional expression (6) below is satisfied:
0.85 <Σd/f< 1.25 (6)
where
f: focal length of an overall optical system of the imaging lens
Σd: distance on the optical axis from the object-side surface of the first lens to the image-side surface of the seventh lens.
8. 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
ih: maximum image height.
9. 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
f 1 : focal length of the first lens
f 2 : focal length of the second lens.
10. 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
f 34 : composite focal length of the third lens and the fourth lens.
11. 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
f 5 : focal length of the fifth lens
f 67 : composite focal length of the sixth lens and the seventh lens.
12. The imaging lens according to claim 1 ,
wherein conditional expressions (13), (14), and (15) below are satisfied:
50<νd5<70 (13)
20<νd6<30 (14)
50<νd7<70 (15)
where
νd 5 : Abbe number of the fifth lens at d-ray
νd 6 : Abbe number of the sixth lens at d-ray
νd 7 : Abbe number of the seventh lens at d-ray.