Imaging lens
An image lens is disclosed. The image lens includes, arranged in succession from the object side to the image side, an aperture stop S 1, a first lens L 1 having two convex surfaces and having a positive refractive power, a second lens L 2 having a meniscus shape convex toward the object side and having a negative refractive power, a third lens L 3 having a positive refractive power, a fourth lens L 4 having a meniscus shape convex toward the image side and having a positive refractive power, and a fifth lens L 5 having a meniscus shape convex toward the object side and having a negative refractive power.
1. An image lens comprising, arranged in succession from the object side to the image side:
an aperture stop S 1 ;
a first lens L 1 having two convex surfaces and having a positive refractive power;
a second lens L 2 having a meniscus shape convex toward the object side and having a negative refractive power;
a third lens L 3 having a meniscus shape convex toward the object side and having a positive refractive power;
a fourth lens L 4 having a meniscus shape convex toward the image side and having a positive refractive power;
a fifth lens L 5 having a meniscus shape convex toward the object side and having a negative refractive power; wherein the following conditions (1)˜(4) are satisfied:
0.600 ≦f 1 /f≦ 0.900 (1)
−1.400 ≦f 2 /f≦− 1.150 (2)
−0.085 ≦R 1 /R 2≦−0.055 (3)
3.000 ≦R 3 /R 4≦6.000 (4)
where,
f is the focal length of the image lens LA;
f 1 is the focal length of the first lens L 1 ;
f 2 is the focal length of the second lens L 2 ;
R 1 is the curvature radius of the object side surface of the first lens L 1 ;
R 2 is the curvature radius of the image side surface of the first lens L 1 ;
R 3 is the curvature radius of the object side surface of the second lens L 2 ;
R 4 is the curvature radius of the image side surface of the second lens L 2 .
2. The image lens as claimed in claim 1 further satisfying the following conditions (5)˜(6):
2.000 ≦f 3 /f≦ 7.000 (5)
0.300 ≦R 5 /R 6≦0.800 (6)
Where:
f is the focal length of the image lens LA;
f 3 is the focal length of the third lens L 3 R 5 is the curvature radius of the surface of the third lens L 3 near the object side;
R 6 is the curvature radius of the surface of the third lens L 3 near the image side.
3. The image lens as claimed in claim 2 further satisfying the following conditions (7)˜(8):
0.300 ≦f 4 /f≦ 0.600 (7)
−0.600 ≦f 5 /f≦− 0.300 (8)
Where:
f is the focal length of the image lens LA;
f 4 is the focal length of the fourth lens L 5 ;
f 5 is the focal length of the fifth lens L 5 .
4. The image lens as claimed in claim 3 further satisfying the following conditions (9)˜(10):
0.125 ≦d 6 /f≦ 0.150 (9)
0.005 ≦d 8 /f≦ 0.020 (10)
Where:
f is the focal length of the image lens LA;
d 6 is the axial distance from the surface of the third lens L 3 near the image side to the surface of the fourth lens L 4 near the object side;
d 8 is the axial distance from the surface of the fourth lens L 4 near the image side to the surface of the fifth lens L 5 near the object side.