JP2006337691A5

JP2006337691A5 -

Info

Publication number: JP2006337691A5
Application number: JP2005161887A
Authority: JP
Filing date: 2005-06-01
Publication date: 2008-05-29

Claims

An imaging optical system comprising, in order from the object side, a negative refractive power lens group and a positive refractive power lens group,
The lens unit having negative refractive power includes, in order from the object side, a first lens that is a negative lens, a second lens that is a negative lens, and a third lens that is a negative lens. In order from the object side, a fourth lens that is a positive lens, a fifth lens that is a negative lens, a sixth lens that is a positive lens, and a seventh lens that is a positive lens,
The imaging optical system, wherein the third lens is a biconcave negative lens.

An imaging optical system comprising, in order from the object side, a negative refractive power lens group and a positive refractive power lens group,
The lens unit having negative refractive power includes, in order from the object side, a first lens that is a negative lens, a second lens that is a negative lens, and a third lens that is a negative lens. In order from the object side, a fourth lens that is a positive lens, a fifth lens that is a negative lens, a sixth lens that is a positive lens, and a seventh lens that is a positive lens,
An imaging optical system, wherein a combined focal length of the fifth lens and the sixth lens is positive.

An imaging optical system comprising, in order from the object side, a negative refractive power lens group and a positive refractive power lens group,
The lens unit having negative refractive power includes, in order from the object side, a first lens that is a negative lens, a second lens that is a negative lens, and a third lens that is a negative lens. In order from the object side, a fourth lens that is a positive lens, a fifth lens that is a negative lens, a sixth lens that is a positive lens, and a seventh lens that is a positive lens,
An aperture stop is disposed between the fourth lens and the fifth lens,
An imaging optical system characterized by satisfying the following conditional expression (1):
0.3 <d4S / Ih <2.5 (1)
However,
d4S: On-axis distance from the image side surface of the fourth lens to the aperture stop Ih: Maximum image height.

An imaging optical system comprising, in order from the object side, a negative refractive power lens group and a positive refractive power lens group,
The lens unit having negative refractive power includes, in order from the object side, a first lens that is a negative lens, a second lens that is a negative lens, and a third lens that is a negative lens. In order from the object side, a fourth lens that is a positive lens, a fifth lens that is a negative lens, a sixth lens that is a positive lens, and a seventh lens that is a positive lens,
An imaging optical system characterized by satisfying the following conditional expression (2):
−0.7 <fN / fP <−0.05 (2)
However,
fN: Composite focal length of a lens unit having negative refractive power fP: Synthetic focal length of a lens unit having positive refractive power

The imaging optical system according to any one of claims 1 to 4, wherein the imaging optical system is configured by only the seven lenses.

5. The imaging optical system according to claim 1, wherein the third lens is a biconcave negative lens, and satisfies the following conditional expression.
2 ≦ | r3f / f | ≦ 100 (3)
However,
r3f: paraxial radius of curvature of the object side surface of the third lens
f: Focal length of the entire imaging optical system
It is.

The imaging optical system according to any one of claims 1 to 4, wherein the following conditional expression is satisfied.
1 ≦ f56 / f ≦ 50 (4)
However,
f56: Composite focal length of the fifth lens and the sixth lens
f: Focal length of the entire imaging optical system
It is.

The imaging optical system according to any one of claims 1 to 4, wherein the following conditional expression is satisfied.
0.3 ≦ f1 / f2 ≦ 1.7 (5)
However,
f1: focal length of the first lens
f2: focal length of the second lens
It is.

The imaging optical system according to any one of claims 1 to 4, wherein the following conditional expression is satisfied.
−5 ≦ f3 / Ih ≦ −1 (6)
However,
f3: focal length of the third lens
Ih: Maximum image height
It is.

The imaging optical system according to any one of claims 1 to 4, wherein the following conditional expression is satisfied.
−0.7 ≦ fN / f4 ≦ −0.1 (7)
However,
fN: Composite focal length of the lens unit having negative refractive power
f4: focal length of the fourth lens
It is.

The imaging optical system according to any one of claims 1 to 4, wherein the following conditional expression is satisfied.
−0.5 ≦ f / r5f ≦ 1 (8)
However,
f: Focal length of the entire imaging optical system
r5f: paraxial radius of curvature of the object side surface of the fifth lens
It is.

The imaging optical system according to any one of claims 1 to 4, wherein the following conditional expression is satisfied.
3 ≦ f7 / Ih ≦ 15 (9)
However,
f7: Focal length of the seventh lens
Ih: Maximum image height
It is.

5. The imaging optical system according to claim 1, wherein an aperture stop is disposed between the fourth lens and the fifth lens.

The fifth lens and the sixth lens are cemented, a cemented surface between the fifth lens and the sixth lens has a negative refractive power, and the Abbe number of the fifth lens is the first lens The imaging optical system according to claim 1, wherein the imaging optical system is smaller than an Abbe number of six lenses.

When the lens component is defined as a lens having only a light incident surface and a light exit surface in contact with air near the optical axis and having no space between them, that is, a single lens or a cemented lens, in order from the object side, Six lens components of first lens, space, second lens, space, third lens, space, fourth lens, space, cemented lens of fifth lens and sixth lens, space, seventh lens, or object In order from the side, the first lens, the space, the second lens, the space, the cemented lens of the third lens and the fourth lens, the space, the cemented lens of the fifth lens and the sixth lens, the space, and the seventh lens. The imaging optical system according to claim 1, comprising a lens component.

The imaging optical system according to any one of claims 2 to 4, wherein the third lens is a biconcave negative lens.

The imaging optical system according to claim 1, wherein a combined focal length of the fifth lens and the sixth lens is positive.

The imaging optical system according to any one of claims 1 to 4, wherein a maximum half angle of view of the imaging optical system satisfies the following conditional expression.
80 ° ≦ ω ≦ 105 ° (10)
However,
ω: Maximum half angle of view of imaging optical system
It is.

5. The imaging optical system according to claim 1, wherein an aperture stop is disposed between the fourth lens and the fifth lens, and the following conditional expression is satisfied: .
0.3 ≦ d4S / Ih ≦ 2.5 (1)
However,
d4S: axial distance from the image side surface of the fourth lens to the aperture stop
Ih: Maximum image height
It is.

The imaging optical system according to any one of claims 1 to 3, wherein the following conditional expression is satisfied.
−0.7 ≦ fN / fP ≦ −0.05 (2)
However,
fN: Composite focal length of the lens unit having negative refractive power
fP: Composite focal length of the lens unit having positive refractive power
It is.

The imaging optical system according to claim 1, wherein the third lens and the fourth lens are cemented.

The imaging optical system according to any one of claims 6 to 21, wherein the imaging optical system includes only the seven lenses.

The first lens is a negative meniscus lens having a convex surface facing the object side,
The second lens is a negative meniscus lens having a convex surface facing the object side,
The third lens is a negative lens in which the absolute value of the paraxial curvature radius of the image side surface is smaller than the absolute value of the paraxial curvature radius of the object side surface;
The fourth lens is a biconvex positive lens;
The fifth lens is a negative lens in which the absolute value of the paraxial curvature radius of the image side surface is smaller than the absolute value of the paraxial curvature radius of the object side surface;
The sixth lens is a biconvex positive lens joined to a fifth lens,
The seventh lens is a positive lens having a convex surface on the object side,
The imaging optical system according to any one of claims 1 to 22, further comprising an aperture stop between the fourth lens and the fifth lens.

In order from the object side, a first lens that is a negative lens, a second lens that is a negative lens, a third lens that is a negative lens, a fourth lens that is a positive lens, a fifth lens that is a negative lens, and a first lens that is a positive lens. The imaging optical system according to any one of claims 1 to 23, further comprising a sixth lens and a seventh lens which is a positive lens, wherein the third lens and the fourth lens are cemented. system.

The imaging optical system according to any one of claims 1 to 24,
A light receiving surface disposed on the image side of the imaging optical system, and an electronic image pickup device that converts an optical image formed on the light receiving surface by the imaging optical system into an electric signal. An imaging device.