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 meniscus lens having a concave image-side surface, a third meniscus lens having a convex image-side surface, a fourth meniscus lens having a concave object-side surface near an optical axis, and a fifth meniscus lens having a concave image-side surface near the optical axis, wherein the image-side surface of the fourth lens has an aspherical shape in which a positive refractive power weakens toward the periphery, and wherein the following conditional expressions (1) and (7) are satisfied: 0.55< f 1/ f <1.0 (1) −1.6< f 2/ f <−0.7 (7) where f represents a focal length of an overall image pickup lens, f1 represents a first lens focal length, and f2 represents a second lens focal length.
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 as a meniscus lens with a concave surface facing the image side,
a third lens as a meniscus lens with a convex surface facing the image side,
a fourth lens as a meniscus lens having a negative refractive power with a concave surface facing the object side near an optical axis, and
a fifth lens as a meniscus lens with a concave surface facing the image side near the optical axis, wherein,
the fourth lens having a convex surface facing the image side near the optical axis, the object-side surface of the fourth lens has an aspherical shape in which the negative refractive power weakens continuously toward a periphery after reaching a maximum value of the negative refractive power of the fourth lens, and
the image-side surface thereof has an aspherical shape in which a positive refractive power weakens toward the periphery, and wherein
the following conditional expressions (1), (7), and (8) are satisfied:
0.55< f 1/ f< 1.0 (1)
−1.6< f 2/ f<− 0.7 (7)
1.05< f 12/ f< 1.60 (8)
where f represents a focal length of an overall optical system of the image pickup lens, f1 represents a focal length of the first lens, f2 represents a focal length of the second lens, and f12 represents a composite focal length of the first and second lenses.
2. The image pickup lens according to claim 1 , satisfying the following conditional expressions (2) through (6):
50< v 1<70 (2)
v 2<35 (3)
50 <v 3<70 (4)
50 <v 4<70 (5)
50 <v 5<70 (6)
where v1 represents an Abbe number of the first lens, v2 represents an Abbe number of the second lens, v3 represents an Abbe number of the third lens, v4 represents an Abbe number of the fourth lens, and v5 represents an Abbe number of the fifth lens.
3. The image pickup lens according to claim 2 , satisfying the following conditional expression (9):
1.7< v 1/ v 2<2.7 (9)
where v1 represents an Abbe number of the first lens, and v2 represents an Abbe number of the second lens.
4. The image pickup lens according to claim 1 , satisfying the following conditional expression (10):
−0.80< f 1/ f 2<−0.45 (10)
where f1 represents a focal length of the first lens, and f2 represents a focal length of the second lens.
5. The image pickup lens according to claim 2 , satisfying the following conditional expression (10):
−0.80< f 1/ f 2<−0.45 (10)
where f1 represents a focal length of the first lens, and f2 represents a focal length of the second lens.
6. 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 front group with a positive refractive power as a whole, and
a rear group with a negative refractive power as a whole;
the front group including:
a first lens having a positive refractive power,
a second lens as a meniscus lens having a negative refractive power with a concave surface facing the image side near the optical axis, and
a third lens as a meniscus lens having a positive refractive power with a convex surface facing the image side near the optical axis;
the rear group including:
a fourth lens as a meniscus lens having a negative reflective power and having both surfaces formed as aspherical surfaces with a convex surface facing the image side near the optical axis, and
a fifth lens as a meniscus lens having both surfaces formed as aspherical surfaces with a concave surface facing the image side near the optical axis; wherein
the fourth lens having a concave surface facing the object side near the optical axis, the object-side surface of the fourth lens has an aspherical shape in which the negative refractive power weakens continuously toward a periphery after reaching a maximum value of the negative refractive power of the fourth lens, and
the image-side surface thereof has an aspherical shape in which a positive refractive power weakens toward the periphery; and wherein
the following conditional expressions (7) and (8) are satisfied:
−1.6< f 2/ f<− 1.0 (7)
1.05< f 12/ f< 1.60 (8)
where f represents a focal length of an overall optical system of the image pickup lens, f2 represents a focal length of the second lens, and f12 represents a composite focal length of the first and second lenses.
7. The image pickup lens according to claim 6 , satisfying the following conditional expressions (2) through (6):
50< v 1<70 (2)
v 2<35 (3)
50< v 3<70 (4)
50< v 4<70 (5)
50< v 5<70 (6)
where v1 represents an Abbe number of the first lens, v2 represents an Abbe number of the second lens, v3 represents an Abbe number of the third lens, v4 represents an Abbe number of the fourth lens, and v5 represents an Abbe number of the fifth lens.
8. The image pickup lens according to claim 6 , satisfying the following conditional expression (1):
0.55< f 1/ f< 1.0 (1)
where f represents a focal length of an overall optical system of the image pickup lens, and f1 represents a focal length of the first lens.
9. The image pickup lens according to claim 7 , satisfying the following conditional expression (9):
1.7< v 1/ v 2<2.7 (9)
where v1 represents an Abbe number of the first lens, and v2 represents an Abbe number of the second lens.
10. The image pickup lens according to claim 6 , satisfying the following conditional expression (10):
−0.80< f 1/ f 2<−0.45 (10)
where f1 represents a focal length of the first lens, and f2 represents a focal length of the second lens.
11. The image pickup lens according to claim 7 , satisfying the following conditional expression (10):
−0.80< f 1/ f 2<−0.45 (10)
where f1 represents a focal length of the first lens, and f2 represents a focal length of the second lens.