Imaging lens
There is provided an imaging lens with high-resolution which satisfies, in well balance, demand of the wide field of view, the low-profileness and the low F-number and excellently corrects aberrations. An imaging lens comprises in order from an object side to an image side, a first lens having negative refractive power, a second lens, a third lens, a fourth lens, and a fifth lens, wherein said second lens has the negative refractive power, and below conditional expressions are satisfied: 0.1< T 2/ T 3<1.16 9< r 3/ r 4<20 −0.1< r 5/ r 6<1.4 where T2: distance along an optical axis from an image-side surface of the second lens to an object-side surface of the third lens, T3: distance along the optical axis from an image-side surface of the third lens to an object-side surface of the fourth lens, r3: paraxial curvature radius of an object-side surface of the second lens, r4: paraxial curvature radius of an image-side surface of the second lens, r5: paraxial curvature radius of an object-side surface of the third lens, and r6: paraxial curvature radius of an image-side surface of the third lens.
1. An imaging lens comprising in order from an object side to an image side,
a first lens having negative refractive power,
a second lens,
a third lens,
a fourth lens, and
a fifth lens, wherein said second lens has the negative refractive power, and below conditional expressions (1), (2) and (3) are satisfied:
0.1< T 2/ T 3<1.16 (1)
9< r 3/ r 4<20 (2)
−0.1< r 5/ r 6<1.4 (3)
where
T2: distance along an optical axis from an image-side surface of the second lens to an object-side surface of the third lens,
T3: distance along the optical axis from an image-side surface of the third lens to an object-side surface of the fourth lens,
r3: paraxial curvature radius of an object-side surface of the second lens,
r4: paraxial curvature radius of an image-side surface of the second lens,
r5: paraxial curvature radius of an object-side surface of the third lens, and
r6: paraxial curvature radius of an image-side surface of the third lens.
2. An imaging lens comprising in order from an object side to an image side,
a first lens having negative refractive power,
a second lens,
a third lens,
a fourth lens, and
a fifth lens, wherein said fourth lens has a biconvex shape having convex surfaces facing both an object side and an image side near an optical axis, and below conditional expressions (1), (3), (4) and (5) are satisfied:
0.1< T 2/ T 3<1.16 (1)
−0.1< r 5/ r 6<1.4 (3)
−1.85<( r 9+ r 10)/( r 9− r 10)<5.00 (4)
−5.1< f 2/ f<− 2.65 (5)
where
T2: distance along an optical axis from an image-side surface of the second lens to an object-side surface of the third lens,
T3: distance along the optical axis from an image-side surface of the third lens to an object-side surface of the fourth lens,
r5: paraxial curvature radius of an object-side surface of the third lens,
r6: paraxial curvature radius of an image-side surface of the third lens,
r9: paraxial curvature radius of an object-side surface of the fifth lens,
r10: paraxial curvature radius of an image-side surface of the fifth lens,
f2: focal length of the second lens, and
f: focal length of the overall optical system of the imaging lens.
3. The imaging lens according to claim 1 , wherein an image-side surface of said fifth lens is a concave surface facing the image side near the optical axis.
4. The imaging lens according to claim 1 , wherein a below conditional expression (6) is satisfied:
−3.5< f 123/ f<− 1.0 (6)
where
f123: composite focal length of the first lens, the second lens and the third lens, and
f: focal length of the overall optical system of the imaging lens.
5. The imaging lens according to claim 1 , wherein a below conditional expression (7) is satisfied:
−9.5< f 1/ f<− 2.5 (7)
where
f1: focal length of the first lens, and
f: focal length of the overall optical system of the imaging lens.
6. The imaging lens according to claim 1 , wherein a below conditional expression (8) is satisfied:
5.7< f 3/ f (8)
where
f3: focal length of the third lens, and
f: focal length of the overall optical system of the imaging lens.
7. The imaging lens according to claim 1 , wherein a below conditional expression (9) is satisfied:
14.5<| f 5|/ f (9)
where
f5: focal length of the fifth lens, and
f: focal length of the overall optical system of the imaging lens.
8. The imaging lens according to claim 1 , wherein a below conditional expression (10) is satisfied:
1.85< r 1/ r 2<5.75 (10)
where
r1: paraxial curvature radius of an object-side surface of the first lens, and
r2: paraxial curvature radius of an image-side surface of the first lens.
9. The imaging lens according to claim 1 , wherein a below conditional expression (11) is satisfied:
−1.85< r 7/ r 8<−0.55 (11)
where
r7: paraxial curvature radius of an object-side surface of the fourth lens, and
r8: paraxial curvature radius of an image-side surface of the fourth lens.
10. The imaging lens according to claim 1 , wherein a below conditional expression (12) is satisfied:
28< vd 4− vd 5<78 (12)
where
vd4: abbe number at d-ray of the fourth lens, and
vd5: abbe number at d-ray of the fifth lens.
11. The imaging lens according to claim 1 , wherein a below conditional expression (13) is satisfied:
Fno≤2.4 (13)
where
Fno: F-number.
12. The imaging lens according to claim 2 , wherein an image-side surface of said fifth lens is a concave surface facing the image side near the optical axis.
13. The imaging lens according to claim 2 , wherein a below conditional expression (6) is satisfied:
−3.5< f 123/ f<− 1.0 (6)
where
f123: composite focal length of the first lens, the second lens and the third lens, and
f: focal length of the overall optical system of the imaging lens.
14. The imaging lens according to claim 2 , wherein a below conditional expression (7) is satisfied:
−9.5< f 1/ f<− 2.5 (7)
where
f1: focal length of the first lens, and
f: focal length of the overall optical system of the imaging lens.
15. The imaging lens according to claim 2 , wherein a below conditional expression (8) is satisfied:
5.7< f 3/ f (8)
where
f3: focal length of the third lens, and
f: focal length of the overall optical system of the imaging lens.
16. The imaging lens according to claim 2 , wherein a below conditional expression (9) is satisfied:
14.5<| f 5|/ f (9)
where
f5: focal length of the fifth lens, and
f: focal length of the overall optical system of the imaging lens.
17. The imaging lens according to claim 2 , wherein a below conditional expression (10) is satisfied:
1.85< r 1/ r 2<5.75 (10)
where
r1: paraxial curvature radius of an object-side surface of the first lens, and
r2: paraxial curvature radius of an image-side surface of the first lens.
18. The imaging lens according to claim 2 , wherein a below conditional expression (11) is satisfied:
−1.85< r 7/ r 8<−0.55 (11)
where
r7: paraxial curvature radius of an object-side surface of the fourth lens, and
r8: paraxial curvature radius of an image-side surface of the fourth lens.
19. The imaging lens according to claim 2 , wherein a below conditional expression (12) is satisfied:
28< vd 4− vd 5<78 (12)
where
vd4: abbe number at d-ray of the fourth lens, and
vd5: abbe number at d-ray of the fifth lens.
20. The imaging lens according to claim 2 , wherein a below conditional expression (13) is satisfied:
Fno≤2.4 (13)
where
Fno: F-number.