Image pickup lens
An image pickup lens includes an aperture stop, a first lens with positive refractive power having a convex object-side surface, a second lens with negative refractive power having a concave image-side surface, a third lens with positive refractive power having a convex image-side surface, a fourth lens with negative refractive power as a double-sided aspheric lens having a concave object-side surface, and a fifth lens with negative refractive power of a meniscus shape as a double-sided aspheric lens having a concave image-side surface, wherein the fifth lens is designed so that the negative refractive power weakens as the distance from the optical axis increases, and wherein the following conditional expression (1) is satisfied: 0.55< f 1/ f <1.0 (1) where f represents a focal length of an overall image pickup lens, and f 1 represents a focal length of the first lens.
1. An image pickup lens composed of five lenses for a solid-state imaging element, comprising, in order from an object side to an image side,
an aperture stop;
a first lens having a positive refractive power with a convex surface facing the object side;
a second lens having a negative refractive power of a meniscus shape with a concave surface facing the image side;
a third lens having a positive refractive power of a meniscus shape with a convex surface facing the image side;
a fourth lens having a negative refractive power and having:
an object-side surface that is concave near an optical axis and has an aspherical shape in which the negative refractive power weakens continuously toward a periphery after reaching a maximum value; and
an image-side surface that is convex near the optical axis and has an aspherical shape in which a positive refractive power weakens continuously toward the periphery after reaching a maximum value; and
a fifth lens having a negative refractive power of a meniscus shape and having both surfaces formed as aspherical surfaces with a concave surface facing the image side near the optical axis, the fifth lens being designed so that the negative refractive power of an entirety thereof weakens as distance from the optical axis increases,
wherein the following conditional expressions (1), (11), (12), and (13) are satisfied:
0.55 <f 1 /f <1.0 (1)
Fno≦2.60 (11)
2ω≧70° (12)
TTL /2 IH ≦0.84 (13)
where f represents a focal length of an overall optical system of the image pickup lens, f 1 represents a focal length of the first lens, Fno represents an F-number, ω represents a half angle of field, TTL represents a total track length, and IH represents a maximum image height.
2. The image pickup lens according to claim 1 , satisfying the following conditional expressions (2) through (6):
50<ν1<70 (2)
ν 2 <35 (3)
50<ν 3 <70 (4)
50<ν4<70 (5)
50<ν5<70 (6)
where ν 1 represents an Abbe number of the first lens, ν 2 represents an Abbe number of the second lens, ν 3 represents an Abbe number of the third lens, ν 4 represents an Abbe number of the fourth lens, and ν 5 represents an Abbe number of the fifth lens.
3. The image pickup lens according to claim 1 , satisfying the following conditional expression (7):
−1.6 <f 2 /f <−0.7 (7)
where f 2 represents a focal length of the second lens.
4. The image pickup lens according to claim 1 , satisfying the following conditional expression (8):
1.05 <f 12 /f <1.60 (8)
where f 12 represents a composite focal length of the first and second lenses.
5. The image pickup lens according to claim 2 , satisfying the following conditional expression (9):
1.7 <ν 1 /ν 2<2.7 (9)
where ν 1 represents an Abbe number of the first lens, and ν 2 represents an Abbe number of the second lens.
6. The image pickup lens according to claim 1 , satisfying the following conditional expression (10):
−0.80 <f 1 /f 2<−0.45 (10)
where fl represents a focal length of the first lens, and f 2 represents a focal length of the second lens.
7. The image pickup lens according to claim 2 , satisfying the following conditional expression (7):
−1.6 <f 2 /f <−0.7 (7)
where f 2 represents a focal length of the second lens.
8. The image pickup lens according to claim 2 , satisfying the following conditional expression (10):
−0.80 <f 1 /f 2<−0.45 (10)
where fl represents a focal length of the first lens, and f 2 represents a focal length of the second lens.