JP2006337690A5

JP2006337690A5 -

Info

Publication number: JP2006337690A5
Application number: JP2005161886A
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 negative refractive power lens group includes a first lens that is a negative lens and a second lens that is a negative lens in order from the object side, and the positive refractive power lens group is a positive lens in order from the object side. A third lens, a fourth lens that is a negative lens, a fifth lens that is a positive lens, and a sixth lens that is a positive lens;
The imaging optical system, wherein the second lens is a biconcave negative lens, and the sixth lens is a biconvex positive 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 negative refractive power lens group includes a first lens that is a negative lens and a second lens that is a negative lens in order from the object side, and the positive refractive power lens group is a positive lens in order from the object side. A third lens, a fourth lens that is a negative lens, a fifth lens that is a positive lens, and a sixth lens that is a positive lens;
An imaging optical system satisfying the following conditional expressions (1) and (2):
−1.2 ≦ fN / Ih ≦ −0.5 (1)
0.85 ≦ f1 / f2 ≦ 1.5 (2)
However,
f1: Focal length of the first lens f2: Focal length of the second lens fN: Composite focal length of the negative refractive power lens group 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 negative refractive power lens group includes a first lens that is a negative lens and a second lens that is a negative lens in order from the object side, and the positive refractive power lens group is a positive lens in order from the object side. A third lens, a fourth lens that is a negative lens, a fifth lens that is a positive lens, and a sixth lens that is a positive lens;
An imaging optical system characterized by satisfying the following conditional expression (3):
2.1 ≦ f5 / f ≦ 4 (3)
However,
f5: focal length of the fifth lens f: focal length of the entire imaging optical system.

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 negative refractive power lens group includes a first lens that is a negative lens and a second lens that is a negative lens in order from the object side, and the positive refractive power lens group is a positive lens in order from the object side. A third lens, a fourth lens that is a negative lens, a fifth lens that is a positive lens, and a sixth lens that is a positive lens;
An aperture stop is disposed between the third lens and the fourth lens,
An imaging optical system characterized by satisfying the following conditional expression (4):
0.7 ≦ d3S / Ih ≦ 2 (4)
However,
d3S: On-axis distance from the image side surface of the third 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 negative refractive power lens group includes a first lens that is a negative lens and a second lens that is a negative lens in order from the object side, and the positive refractive power lens group is a positive lens in order from the object side. A third lens, a fourth lens that is a negative lens, a fifth lens that is a positive lens, and a sixth lens that is a positive lens;
An imaging optical system that satisfies the following conditional expression (5):
−0.35 ≦ fN / fP ≦ −0.1 (5)
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 claim 1, wherein the imaging optical system includes only the six lenses.

The imaging optical system according to claim 1, wherein the second lens is a biconcave negative lens and satisfies the following conditional expression.
6 ≦ | r2f / f | ≦ 200 (6)
However,
r2f: paraxial radius of curvature of the object side surface of the second lens
f: Focal length of the entire imaging optical system
It is.

The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.
1.2 ≦ f3 / f5 ≦ 2.5 (7)
However,
f3: focal length of the third lens
f5: focal length of the fifth lens
It is.

The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.
1.5 ≦ f45 / f6 ≦ 6 (8)
However,
f45: Composite focal length of the fourth lens and the fifth lens
f6: focal length of the sixth lens
It is.

The imaging optical system according to claim 1, wherein the sixth lens is a biconvex positive lens and satisfies the following conditional expression.
−0.8 ≦ (r6f + r6r) / (r6f−r6r) ≦ 0.8 (9)
However,
r6f: paraxial radius of curvature of the object side surface of the sixth lens
r6r: Paraxial radius of curvature of the image side surface of the sixth lens
It is.

The imaging optical system according to any one of claims 1 to 3, wherein an aperture stop is disposed between the third lens and the fourth lens.

The fourth lens and the fifth lens are cemented, a cemented surface between the fourth lens and the fifth lens has a negative refractive power, and the Abbe number of the fourth 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 five 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, The first lens, the space, the second lens, the space, the third lens, the space, the cemented lens of the fourth lens and the fifth lens, the space, and the sixth lens. 6. The imaging optical system according to any one of items 1 to 5.

6. The imaging optical system according to claim 2, wherein the second lens is a biconcave negative lens.

6. The imaging optical system according to claim 2, wherein the sixth lens is a biconvex positive lens.

The imaging optical system according to any one of claims 1 to 5, 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.

The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.
0.85 ≦ f1 / f2 ≦ 1.5 (2)
However,
f1: focal length of the first lens
f2: focal length of the second lens
It is.

The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.
−1.2 ≦ fN / Ih ≦ −0.5 (1)
However,
fN: Composite focal length of the lens unit having negative refractive power
Ih: Maximum image height
It is.

The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.
2.1 ≦ f5 / f ≦ 4 (3)
However,
f5: focal length of the fifth lens
f: Focal length of the entire imaging optical system
It is.

6. The imaging optical system according to claim 1, wherein an aperture stop is disposed between the third lens and the fourth lens, and the following conditional expression is satisfied: .
0.7 ≦ d3S / Ih ≦ 2 (4)
However,
d3S: axial distance from the image side surface of the third lens to the aperture stop
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.
−0.35 ≦ fN / fP ≦ −0.1 (5)
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 any one of claims 7 to 21, wherein the imaging optical system includes only the six lenses.

The imaging optical system according to any one of claims 1 to 22, wherein the following conditional expression is satisfied.
0.7 ≦ r1r / d1r ≦ 1.5 (11)
However,
r1r: Paraxial radius of curvature of the image side surface of the first lens
d1r: On-axis distance from the image side surface of the first lens to the object side surface of the second lens
It is.

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

An 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.