JP2008268613A5

JP2008268613A5 -

Info

Publication number: JP2008268613A5
Application number: JP2007112515A
Authority: JP
Filing date: 2007-04-23
Publication date: 2010-11-04
Anticipated expiration: 2027-04-23

Claims

A first lens group having a positive refractive power, arranged in order from the object side along the optical axis, an aperture stop, and a second lens group having a positive refractive power;
The first lens group includes a first negative meniscus lens having a convex surface facing the object side, a second negative meniscus lens having a convex surface facing the object side, and a convex surface facing the object side. A third group of negative meniscus lenses facing and a front group including a positive lens, wherein at least one aspheric surface is provided in the front group,
The first lens group is fixed and the second lens group is moved along the optical axis at the time of focusing from an object at infinity to a near object,
An antireflection film is provided on at least one of the optical surfaces in the first lens group, and the antireflection film is configured to include at least one layer formed using a wet process. Wide angle lens.

The antireflection film is a multilayer film,
The wide-angle lens according to claim 1, wherein the layer formed by using the wet process is a layer on a most surface side among layers constituting the multilayer film.

When the refractive index of the layer formed by using the wet process is nd, the following formula nd ≦ 1.30
The wide-angle lens according to claim 1 or 2, wherein the following condition is satisfied.

A first lens group having a positive refractive power, arranged in order from the object side along the optical axis, an aperture stop, and a second lens group having a positive refractive power;
The first lens group includes a first negative meniscus lens having a convex surface facing the object side, a second negative meniscus lens having a convex surface facing the object side, and a convex surface facing the object side. A third group of negative meniscus lenses facing and a front group including a positive lens, wherein at least one aspheric surface is provided in the front group,
The first lens group is fixed and the second lens group moves along the optical axis when focusing from an object at infinity to an object at a short distance,
An antireflection film is provided on at least one of the optical surfaces of the first lens group, and the antireflection film includes at least one layer having a refractive index of 1.30 or less. Wide angle lens.

The antireflection film is a multilayer film,
5. The wide-angle lens according to claim 4, wherein the layer having a refractive index of 1.30 or less is the most surface layer among the layers constituting the multilayer film.

The wide-angle lens according to claim 1, wherein the optical surface having the antireflection film is a concave surface with respect to the aperture stop.

The wide-angle lens according to any one of claims 1 to 6, wherein the optical surface having the antireflection film is an object-side surface of the second negative meniscus lens.

8. The wide-angle lens according to claim 1, wherein the optical surface having the antireflection film is an image-side surface of the first negative meniscus lens. 9.

The focal length of the entire wide-angle lens system is f, and the distance on the optical axis between the most object side lens surface of the second lens group and the most image side lens surface of the second lens group is D2. When the following formula D2 / f <1.00
Wide-angle lens according to claims 1 to any one of claims 8, characterized by satisfying the condition.

The wide-angle lens according to any one of claims 1 to 9 , wherein the second lens group includes five or less lenses.

When the focal length of the entire wide-angle lens system is f and the focal length of the first lens group is f1, the following formula 2.50 <f1 / f <30.00
When the distance on the optical axis between the lens surface closest to the image side of the first lens unit and the lens surface closest to the object side of the second lens unit is D12, .30 <D12 / f <1.50
The wide-angle lens according to any one of claims 1 to 10 , wherein the following condition is satisfied.

When the focal length of the first lens group is f1, and the focal length of the second lens group is f2, the following expression 0.70 <f1 / f2 <13.00
Wide-angle lens according to claims 1 to any one of claims 11, characterized by satisfying the condition.

The second lens group includes a plurality of positive lenses and a plurality of negative lenses. The difference between the average dispersion value of the plurality of positive lenses and the average dispersion value of the plurality of negative lenses is Δν2. Then, the following formula 36.00 <Δν2
Wide-angle lens according to claims 1 to any one of claims 12, characterized by satisfying the condition.

The first lens group has a rear group disposed on the image side of the front group. When the focal length of the front group is f1a and the focal length of the rear group is f1b, 0.25 <(− f1a) / f1b <2.00
The wide-angle lens according to any one of claims 1 to 13 , wherein the following condition is satisfied.

In an imaging apparatus including a wide-angle lens that forms an image of an object on a predetermined surface,
Imaging device, wherein the wide-angle lens is a wide-angle lens according to any one of claims 14 claim 1.

Focusing of a wide-angle lens including a first lens group having a positive refractive power, an aperture stop, and a second lens group having a positive refractive power, arranged in order from the object side along the optical axis. In the method
The first lens group includes a first negative meniscus lens having a convex surface facing the object side, a second negative meniscus lens having a convex surface facing the object side, and a convex surface facing the object side. A third group of negative meniscus lenses facing and a front group including a positive lens, wherein at least one aspheric surface is provided in the front group,
The first lens group is fixed and the second lens group is moved along the optical axis at the time of focusing from an object at infinity to an object at a short distance,
A wide-angle lens, wherein an antireflection film is provided on at least one of the optical surfaces in the first lens group, and the antireflection film includes at least one layer formed by a wet process. How to focus.