Imaging device and imaging lens
An imaging device of the disclosure includes an imaging lens; an imaging element that converts an optical image formed on an image forming surface by the imaging lens, into an electric signal; and a computing device that corrects distortion aberration of an image picked up by the imaging element. The imaging lens includes, in order from object side, a front-group lens system having positive refractive power, and a rear-group lens system having negative refractive power, a lens surface on a closest side to the image of the rear-group lens system being concave on an image side near an optical axis and convex on the image side around a periphery, and the following conditional expression is satisfied: 5(%)< OD Max <20(%) (1) where OD Max is a maximum value of distortion aberration within an imaging region of the imaging lens.
1. An imaging device, comprising:
an imaging lens that includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens in this order from an object side, wherein
the first lens includes an object side surface that is on a closest side to an object,
the object side indicates a side that corresponds to the object,
the third lens includes a first lens surface on an image side,
the fourth lens includes a second lens surface on the object side and a third lens surface on the image side,
the fifth lens includes a fourth lens surface on the object side,
a distance between the first lens surface and the second lens surface is greater than a distance between the third lens surface and the fourth lens surface, and
a value of a paraxial curvature radius of each of the second lens surface and the third lens surface is positive;
an imaging element configured to:
pickup an optical image from an image forming surface of the imaging lens; and
convert the optical image into an electric signal; and
a computing device configured to correct distortion aberration of the optical image, wherein
the imaging lens further includes, in order from the object side, a front-group lens system having positive refractive power and a rear-group lens system,
the front-group lens system includes the first lens,
the rear-group lens system includes, on a closest side to the image forming surface, the fifth lens,
the fifth lens further includes a fifth lens surface on the image side,
the fifth lens surface is concave near an optical axis and convex around a periphery, and
the imaging lens satisfies the following conditional expressions:
5(%)< OD Max <20(%) (1)
0.55<Linf/ D 0.582 . . . (2)
f ra <0 (3)
f rb <0 (4)
where OD Max is a maximum value of the distortion aberration within an imaging region of the imaging lens,
Linf is a distance from the object side surface to the image forming surface when the imaging lens is focused on infinity,
f ra is a synthetic focal length of the second lens, the third lens, the fourth lens, and the fifth lens,
f rb is a synthetic focal length of the fourth lens and the fifth lens,
the distance is on the optical axis, and
D is a diagonal length of the image forming surface.
2. The imaging device according to claim 1 , wherein
the first lens has the positive refractive power and the second lens has negative refractive power.
3. The imaging device according to claim 1 , wherein
the front-group lens system further includes the second lens, the third lens, and the fourth lens.
4. An imaging lens, comprising: in order from an object side
a front-group lens system having positive refractive power; and
a rear-group lens system, wherein
the object side indicates a side that corresponds to an object,
the imaging lens includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens in this order from the object side,
the first lens includes an object side surface that is on a closest side to the object,
the third lens includes a first lens surface on an image side,
the fourth lens includes a second lens surface on the object side and a third lens surface on the image side,
the fifth lens includes a fourth lens surface on the object side,
a distance between the first lens surface and the second lens surface is greater than a distance between the third lens surface and the fourth lens surface,
a value of a paraxial curvature radius of each of the second lens surface and the third lens surface is positive,
the front-group lens system includes the first lens,
the rear-group lens system includes, on a closest side to an image forming surface, the fifth lens,
the fifth lens further includes a fifth lens surface on the image side,
the fifth lens surface is concave near an optical axis and convex around a periphery,
the imaging lens satisfies the following conditional expressions:
5(%)< OD Max <20(%) (1)
0.55<Linf/ D 0.582 . . . (2)
f ra <0 (3)
f rb <0 (4)
where OD Max is a maximum value of a distortion aberration within an imaging region of the imaging lens,
Linf is a distance from the object side surface to the image forming surface when the imaging lens is focused on infinity,
f ra is a synthetic focal length of the second lens, the third lens, the fourth lens, and the fifth lens,
f rb is a synthetic focal length of the fourth lens and the fifth lens,
the distance is on the optical axis, and
D is a diagonal length of the image forming surface.
5. The imaging lens according to claim 4 , wherein
the first lens has the positive refractive power and the second lens has negative refractive power.