US 7,679,837 B2Granted

Zoom optical system, image pickup device, and digital apparatus

AssigneeKonica Minolta Opto, Inc.

InventorYoshihito Souma

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Abstract

A zoom optical system at least includes in the order from an object side: a first lens group having a positive optical power; a second lens group having a negative optical power; and a third lens group having a positive optical power. In zooming from a wide angle end to a telephoto end, a distance between the first lens group and the second lens group is increased, and a distance between the second lens group and the third lens group is decreased. The first lens group includes at least one negative lens element, and the second lens group includes a negative lens element closest to the object side, with a lens surface of the negative lens element being concave toward an image side. The zoom optical system satisfies the following conditional expressions (1) and (2): vd2<30 (1) 50>vd1n>30 (2) where vd2 represents the Abbe number of the negative lens element closest to the object side in the second lens group, and vd1n represents an Abbe number of a negative lens element, or an average Abbe number of negative lens elements in the first lens group.

Claims18

Dependent claims

A zoom optical system at least comprising in the order from an object side:

a first lens group having a positive optical power;
a second lens group having a negative optical power;
and
a third lens group having a positive optical power, wherein
in zooming from a wide angle end to a telephoto end, a distance between the first lens group and the second lens group is increased, and a distance between the second lens group and the third lens group is decreased, and
the first lens group includes at least one negative lens element, and the second lens group includes a negative lens element closest to the object side, with a lens surface of the negative lens element closest to the object side being concave toward an image side, and
the zoom optical system satisfies the following conditional expressions (1) and (2):
vd2<30 (1)
50>vd1n>30 (2)
where vd2 represents the Abbe number of the negative lens element closest to the object side in the second lens group, and vd1n represents an Abbe number of a negative lens element, or an average Abbe number of negative lens elements in the first lens group, and
wherein the negative lens element closest to the object side in the second lens group satisfies the following conditional expression (10):
hb/fw≧1.5 (10)
where hb represents an off-axis ray height on the lens surface closest to the object side in the second lens group, and is a value calculated by paraxial approximation in the case where a ray whose tangent of incident angle is 1.0 is incident onto the zoom optical system in a manner that the ray intersects with an optical axis at a diaphragm position, and fw represents a focal length of an entirety of the zoom optical system at the wide angle end.

10 more elements

An image pickup device, comprising:

a zoom optical system at least including in the order from an object side:
a first lens group having a positive optical power;
a second lens group having a negative optical power;
and
a third lens group having a positive optical power, wherein
in zooming from a wide angle end to a telephoto end, a distance between the first lens group and the second lens group is increased, and a distance between the second lens group and the third lens group is decreased, and
the first lens group includes at least one negative lens element, and the second lens group includes a negative lens element closest to the object side, with a lens surface of the negative lens element closest to the object side being concave toward an image side, and
the zoom optical system satisfies the following conditional expressions (1) and (2):
vd2<30 (1)
50>vd1n>30 (2)
where vd2 represents the Abbe number of the negative lens element closest to the object side in the second lens group, and vd1n represents an Abbe number of a negative lens element, or an average Abbe number of negative lens elements in the first lens group;
and
an image sensor, with a light receiving surface, for converting an optical image of a subject into an electrical signal, wherein
the zoom optical system is so configured as to form the optical image of the subject on the light receiving surface of the image sensor, and
wherein the negative lens element closest to the object side in the second lens group satisfies the following conditional expression (10):
hb/fw≧1.5 (10)
where hb represents an off-axis ray height on the lens surface closest to the object side in the second lens group, and is a value calculated by paraxial approximation in the case where a ray whose tangent of incident angle is 1.0 is incident onto the zoom optical system in a manner that the ray intersects with an optical axis at a diaphragm position, and fw represents a focal length of an entirety of the zoom optical system at the wide angle end.

14 more elements

A digital apparatus, comprising:

an image pickup device including
a zoom optical system at least having in the order from an object side:
a first lens group having a positive optical power;
a second lens group having a negative optical power;
and
a third lens group having a positive optical power, wherein
in zooming from a wide angle end to a telephoto end, a distance between the first lens group and the second lens group is increased, and a distance between the second lens group and the third lens group is decreased, and
the first lens group includes at least one negative lens element, and the second lens group includes a negative lens element closest to the object side, with a lens surface of the negative lens element closest to the object side being concave toward an image side, and
the zoom optical system satisfies the following conditional expressions (1) and (2):
vd2<30 (1)
50>vd1n>30 (2)
where vd2 represents the Abbe number of the negative lens element closest to the object side in the second lens group, and vd1 represents an Abbe number of a negative lens element, or an average Abbe number of negative lens elements in the first lens group;
and
an image sensor, with a light receiving surface, for converting an optical image of a subject into an electrical signal, wherein
the zoom optical system is so configured as to form the optical image of the subject on the light receiving surface of the image sensor;
and
a controller for causing the image sensor to perform at least one of a still image photographing operation and a moving image photographing operation of the subject, wherein
the zoom optical system is mounted on the image sensor to form the optical image of the subject on the light receiving surface of the image sensor, and
wherein the negative lens element closest to the object side in the second lens group satisfies the following conditional expression (10):
hb/fw≧1.5 (10)
where hb represents an off-axis ray height on the lens surface closest to the object side in the second lens group, and is a value calculated by paraxial approximation in the case where a ray whose tangent of incident angle is 1.0 is incident onto the zoom optical system in a manner that the ray intersects with an optical axis at a diaphragm position, and fw represents a focal length of an entirety of the zoom optical system at the wide angle end.

18 more elements

Dependencies are inferred from the claim text.