Image pickup lens
An image pickup lens includes a first lens with positive refractive power having a convex object side surface, an aperture stop, a second lens with negative refractive power having a convex image side surface, a third lens with positive refractive power having a concave image side surface, a fourth lens with positive refractive power having a convex image side surface, and a fifth lens with negative refractive power as a double-sided aspheric lens having a concave image side surface near the optical axis; wherein the first lens and the second lens satisfy following conditional expressions (1) and (2); 50<ν1<85 (1) 20<ν2<35 (2) where ν1 represents an Abbe number of the first lens, and ν2 represents an Abbe number of the second lens, and where the second lens satisfies a following conditional expression (3); 1.55< Nd 2<1.70 (3) where Nd2 represents a refractive index of d-ray of the second lens.
1. An image pickup lens composed of five lenses for a solid imaging element, comprising, in order from an object side to an image side, a first lens having a positive refractive power with a convex surface facing the object side, an aperture stop, and a second lens having a negative refractive power with a convex surface facing the image side;
wherein the first lens and the second lens satisfy following conditional expressions (1) and (2);
50<ν1<85 (1)
23.91≦ν2<35 (2)
where ν1 represents an Abbe number of the first lens, and ν2 represents an Abbe number of the second lens, and where the second lens satisfies a following conditional expression (3);
1.55< Nd 2<1.70 (3)
where Nd2 represents a refractive index of d-ray of the second lens,
wherein the image pickup lens further comprises a third lens having a positive refractive power with a concave surface facing the image side, a fourth lens having a positive refractive power and having a meniscus shape with a convex surface facing the image side,
wherein the third lens and the fourth lens satisfy following conditional expressions (5) and (6);
23.91≦ν3<30 (5)
50<ν4<60 (6)
where ν3 represents an Abbe number of the third lens, and ν4 represents an Abbe number of the fourth lens, and where the third lens satisfies a following conditional expression (7);
1.5<Nd3<1.7 (7)
where Nd3 represents a refractive index of d-ray of the third lens, and
wherein the image pickup lens further comprises a fifth lens having both sides formed as aspherical surfaces and having a negative refractive power with a concave surface facing the image side near the optical axis.
2. The image pickup lens according to claim 1 , wherein the fourth lens has a meniscus shape near the optical axis, and a surface thereof facing the image side has an aspheric shape in which a positive refractive power weakens toward a circumference.
3. The image pickup lens according to claim 1 , wherein the fifth lens has both surfaces thereof formed as concave surfaces near the optical axis, and has a pole-change point other than on the optical axis on an aspheric surface facing the image side.
4. The image pickup lens according to claim 1 , satisfying a following conditional expression (9):
1.0<|( r 3+ r 4)/( r 3− r 4)|<1.3 (9)
where r3 represents a curvature radius of an object side surface of the second lens, and r4 represents a curvature radius of an image side surface of the second lens.
5. The image pickup lens according to claim 1 , satisfying a following conditional expression (10):
1.7 <r 2/ r 3<6.0 (10)
where r2 represents a curvature radius of an image side surface of the first lens, and r3 represents a curvature radius of an object side surface of the second lens.
6. The image pickup lens according to claim 1 , satisfying a following conditional expression (11):
0.5 <f 1 /f< 0.8 (11)
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.
7. The image pickup lens according to claim 1 , satisfying a following conditional expression (12):
−1.1 <f 2 /f<− 0.7 (12)
where f represents a focal length of an overall system of the image pickup lens, and f2 represents a focal length of the second lens.
8. The image pickup lens according to claim 1 , satisfying a following conditional expression (13):
0.5 <f 4 /f< 0.7 (13)
where f represents a focal length of an overall optical system of the impace pickup lens, and f4 represents a focal length of the fourth lens.
9. An image pickup lens composed of five lenses for a solid imaging element, comprising, in order from an object side to an image side, a first lens having a positive refractive power with a convex surface facing the object side, an aperture stop, a second lens having a negative refractive power with a convex surface facing the image side, a third lens having both sides formed as aspherical surfaces and having a positive refractive power, a fourth lens having an image side formed as aspherical surface and having a meniscus shape with a convex surface facing the image side, and a fifth lens having both sides formed as aspherical surfaces with a concave surface facing the image side near the optical axis, and
conditional expressions (5), (6) and (7) are satisfied:
23.91≦ν3<30 (5)
50<ν4<60 (6)
1.5<Nd3<1.7 (7)
where ν3 represents an Abbe number of the third lens, ν4 represents an Abbe number of the fourth lens, and Nd3 represents a refractive index of d-ray of the third lens.
10. The image pickup lens according to claim 9 , satisfying following conditional expressions (1), (2), and (3):
50<ν1<85 (1)
23.91≦ν2<35 (2)
1.55<Nd2<1.70 (3)
where ν1 represents an Abbe number of the first lens, ν2 represents an Abbe number of the second lens, Nd2 represents a refractive index of d-ray of the second lens.
11. The image pickup lens according to claim 9 , wherein the fifth lens has both surfaces thereof formed as concave surfaces near the optical axis, and has a pole-change point other than on the optical axis on an aspheric surface facing the image side.
12. The image pickup lens according to claim 9 , satisfying a following conditional expression (9):
1.0<|( r 3 +r 4)/( r 3 −r 4)|<1.3 (9)
where r3 represents a curvature radius of an object side surface of the second lens, and r4 represents a curvature radius of an image side surface of the second lens.
13. The image pickup lens according to claim 9 , satisfying a following conditional expression (11):
0.5< f 1 /f< 0.8 (11)
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.
14. The image pickup lens according to claim 9 , satisfying a following conditional expression (12):
−1.1 <f 2 /f<− 0.7 (12)
where f represents a focal length of an overall optical system of the image pickup lens, and f2 represents a focal length of the second lens.
15. The image pickup lens according to claim 9 , satisfying a following conditional expression (13):
0.5< f 4 /f< 0.7 (13)
where f represents a focal length of an overall optical system of the image pickup lens, and f4 represents a focal length of the fourth lens.
16. The image pickup lens according to claim 9 , satisfying a following conditional expression (10):
1.7 <r 2 /r 3<6.0 (10)
where r2 represents a curvature radius of an image side surface of the first lens, and r3 represents a curvature radius of an object side surface of the second lens.