Imaging lens
There is provided an imaging lens with small telephoto ratio and excellent optical characteristics which satisfies demand of the downsizing, the low-profileness and the low F-number. An imaging lens comprises, in order from an object side to an image side, a first lens with positive refractive power, a second lens, a third lens, a fourth lens being a double-sided aspheric lens, a fifth lens being a double-sided aspheric lens, and a sixth lens having a convex surface facing the image side, and a below conditional expression is satisfied: 0.60<TTL/ f <1.00 where TTL: a total track length, and f: a focal length of the overall optical system of the imaging lens.
1. An imaging lens comprising, in order from an object side to an image side:
a first lens;
a second lens with negative refractive power;
a third lens;
a fourth lens;
a fifth lens with negative refractive power; and
a sixth lens with negative refractive power,
wherein said fourth lens has at least one aspheric surface,
said sixth lens has a convex surface facing the image-side at a paraxial region, and
below conditional expressions (1) and (4) are satisfied:
0.06<TTL/ f <1.00 (1)
0.50 <r 10 /f <1.00 (4)
0.05 <D 6 /f <0.25 (10)
where:
TTL: a total track length,
f: a focal length of an overall optical system of the imaging lens,
r10: a paraxial curvature radius of an image-side surface of the fifth lens, and
D6: a thickness of the sixth lens along the optical axis.
2. The imaging lens according to claim 1 , wherein a below conditional expression (5) is satisfied:
−13.00 <r 12 /f <−1.90 (5)
where:
r12: a paraxial curvature radius of an image-side surface of the sixth lens.
3. The imaging lens according to claim 1 , wherein a below conditional expression (7) is satisfied:
−1.30 <f 2 /f <−0.70 (7)
where:
f2: a focal length of the second lens.
4. The imaging lens according to claim 1 , wherein a below conditional expression (8) is satisfied:
−1.80 <f 5 /f <−0.80 (8)
where:
f5: a focal length of the fifth lens.
5. The imaging lens according to claim 1 , wherein a below conditional expression (9) is satisfied:
0.30 <T 3 /T 4<0.90 (9)
where:
T3: a distance along the optical axis from an image-side surface of the third lens to an object-side surface of the fourth lens, and
T4: a distance along the optical axis from an image-side surface of the fourth lens to an object-side surface of the fifth lens.
6. The imaging lens according to claim 1 , wherein a below conditional expression (11) is satisfied:
1.80 <|r 9 |/f <19.00 (11)
where:
r9: a paraxial curvature radius of an object-side surface of the fifth lens.
7. The imaging lens according to claim 1 , wherein a below conditional expression (12) is satisfied:
3.5 <|f 3 |/f (12)
where
f3: a focal length of the third lens.
8. The imaging lens according to claim 1 , wherein a below conditional expression (15) is satisfied:
0.60<TTL/(2×ih)<1.00 (15)
where:
ih: a maximum image height.
9. An imaging lens comprising, in order from an object side to an image side:
a first lens with positive refractive power;
a second lens;
a third lens;
a fourth lens;
a fifth lens; and
a sixth lens with negative refractive power,
wherein said second lens has a concave surface facing the image-side at a paraxial region,
said sixth lens has a convex surface facing the image-side at a paraxial region, and
below conditional expressions (4) and (26) are satisfied:
0.50 <r 10 /f <1.00 (4)
T 1 <T 2 <T 3< T 4 (26)
where:
f: a focal length of the overall optical system of the imaging lens,
r10: a paraxial curvature radius of an image-side surface of the fifth lens,
T1: a distance along the optical axis from an image-side surface of the first lens to an object-side surface of the second lens,
T2: a distance along the optical axis from an image-side surface of the second lens to an object-side surface of the third lens,
T3: a distance along the optical axis from an image-side surface of the third lens to an object-side surface of the fourth lens, and
T4: a distance along the optical axis from an image-side surface of the fourth lens to an object-side surface of the fifth lens.
10. The imaging lens according to claim 9 , wherein a below conditional expression (5) is satisfied:
−13.00 <r 12 /f <−1.90 (5)
where:
r12: a paraxial curvature radius of an image-side surface of the sixth lens.
11. The imaging lens according to claim 9 , wherein a below conditional expression (7) is satisfied:
−1.30 <f 2 /f <−0.70 (7)
where:
f2: a focal length of the second lens.
12. The imaging lens according to claim 9 , wherein a below conditional expression (8) is satisfied:
−1.80 <f 5 /f <−0.80 (8)
where:
f5: a focal length of the fifth lens.
13. The imaging lens according to claim 9 , wherein a below conditional expression (9) is satisfied:
0.30 <T 3 /T 4<0.90 (9)
where:
T3: a distance along the optical axis from an image-side surface of the third lens to an object-side surface of the fourth lens, and
T4: a distance along the optical axis from an image-side surface of the fourth lens to an object-side surface of the fifth lens.
14. The imaging lens according to claim 9 , wherein a below conditional expression (11) is satisfied:
1.80 <|r 9 |/f <19.00 (11)
where:
r9: a paraxial curvature radius of an object-side surface of the fifth lens.
15. The imaging lens according to claim 9 , wherein a below conditional expression (12) is satisfied:
3.5 <|f 3 |/f (12)
where:
f3: a focal length of the third lens.
16. The imaging lens according to claim 9 , wherein a below conditional expression (15) is satisfied:
0.60<TTL/(2×ih)<1.00 (15)
where:
TTL: a total track length, and
ih: a maximum image height.