Image-forming lens, and camera device and portable information terminal device with the image-forming lens
An image forming lens consists of from an object side to an image side in the following order: a first group with a positive refractive power; an aperture stop; and a second group with a positive refractive power, wherein the second group includes, from the object side to the image side in the following order, a biconvex lens, a biconcave lens, a negative meniscus lens a convex surface of which faces the image side, a biconvex lens, and a positive meniscus lens a convex surface of which faces the image side.
1. An image forming lens consisting of from an object side to an image side in the following order:
a first group with a positive refractive power;
an aperture stop; and
a second group with a positive refractive power,
wherein the second group includes, from the object side to the image side in the following order, a biconvex lens, a biconcave lens, a negative meniscus lens a convex surface of which faces the image side, a biconvex lens, and a positive meniscus lens a convex surface of which faces the image side.
2. The image forming lens according to claim 1 , wherein focusing to a limited object distance is performed by shifting each of the first group and the second group by a different extension amount.
3. The image forming lens according to claim 1 , wherein a lens surface on a most image side of the first group, and a lens surface on a most object side of the second group have convex shapes.
4. The image forming lens according to claim 1 , wherein an interval between the first group and the second group in a case where an object position is at infinity: D 1 ∞ , an interval between the first group and the second group in a case of focusing to a reference closest imaging distance: D 1 t , an interval between the second group and an image plane in a case where the object position is at infinity: D 2 ∞ and an interval between the second group and the image plane in a case of focusing to the reference closest imaging distance: D 2 t satisfy Conditional Expression J: −1.0<Log|(D 1 ∞ −D 1 t )/(D 2 ∞ −D 2 t )|<−0.4, where Log is taken as a common logarithm.
5. An information device having an imaging function comprising the image-forming lens according to claim 1 as an imaging optical system.
6. An imaging apparatus comprising the image-forming lens according to claim 1 as a shooting optical system.
7. An image forming lens consisting of from an object side to an image side in the following order:
a first group with a positive refractive power;
an aperture stop; and
a second group with a positive refractive power,
wherein the second group includes, from the object side to the image side in the following order, a biconvex lens in which an absolute value of a radius of curvature on the image side is smaller than that on the object side, a biconcave lens that is cemented with the biconvex lens, in which an absolute value of a radius of curvature on the object side is smaller than that on the image side, a negative meniscus lens a convex surface of which faces the image side, a biconvex lens in which an absolute value of a radius of curvature on the image side is smaller than that on the object side, and a positive meniscus lens that has an aspheric surface, a convex surface of which faces the image side.
8. The image forming lens according to claim 7 , wherein an interval between the first group and the second group in a case where an object position is at infinity: D 1 ∞ , an interval between the first group and the second group in a case of focusing to a reference closest imaging distance: D 1 t , an interval between the second group and an image plane in a case where the object position is at infinity: D 2 ∞ , and an interval between the second group and the image plane in a case of focusing to the reference closest imagining distance: D 2 t satisfy Conditional Expression J: −1.0<Log|(D 1 ∞ −D 1 t )/(D 2 ∞ −D 2 t )|<−0.4, where Log is taken as a common logarithm.
9. An information device having an imaging function comprising the image-forming lens according to claim 7 as an imaging optical system.
10. An imaging apparatus comprising the image-forming lens according to claim 7 as a shooting optical system.
11. An image forming lens consisting of from an object side to an image side in the following order:
a first group with a positive refractive power;
an aperture stop; and
a second group with a positive refractive power,
wherein the second group includes five lens elements including at least one cemented lens in which two lens elements of a positive lens and a negative lens are cemented to each other, and the second group includes, from the object side to the image side in the following order, a biconvex lens, a biconcave lens, a negative meniscus lens a convex surface of which faces the image side, a biconvex lens, and a positive meniscus lens a convex surface of which faces the image side.
12. An image forming lens consisting of from an object side to an image side in the following order:
a first group with a positive refractive power;
an aperture stop; and
a second group with a positive refractive power,
wherein the second group includes, from the object side to the image side in the following order, a first biconvex lens, a biconcave lens, a negative meniscus lens a convex surface of which faces the image side, a second biconvex lens, and a positive meniscus lens a convex surface of which faces the image side, and the first biconvex lens and the biconcave lens are cemented.