JP2007017638A5

JP2007017638A5 -

Info

Publication number: JP2007017638A5
Application number: JP2005198100A
Authority: JP
Filing date: 2005-07-06
Publication date: 2008-08-14

Claims

A first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side. ,
The first lens group includes at least two lenses including one negative lens having a composite aspherical surface and one positive lens,
The second lens group includes at least three lenses including a positive lens having both convex surfaces and a cemented lens of a positive lens and a negative lens;
The third lens group includes at least one lens including a positive lens,
A zoom lens, wherein zooming is performed by changing an interval between the lens groups while suppressing an amount of movement of the second lens group in the direction along the optical axis.

A first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side. ,
The first lens group includes at least two lenses including one negative lens and one positive lens on which an aspheric surface is formed,
The second lens group includes at least three lenses including a positive lens having both convex surfaces and a cemented lens of a positive lens and a negative lens;
The third lens group includes at least one lens including a positive lens,
To suppress the movement amount in the direction along the optical axis of the second lens group, wherein changing the spacing between the lens units have rows zooming, a positive lens included in the third lens group consists of a plastic material A zoom lens characterized in that an aspheric surface is formed on any surface of the positive lens.

2. The zoom lens according to claim 1 , wherein a positive lens included in the third lens group is made of a plastic material, and an aspheric surface is formed on any surface of the positive lens.

The radius of curvature of the image side surface of the positive lens included in the first lens group is increased to shorten the interval between the negative lens and the positive lens included in the first lens group, and the first lens group. The balance of the focal lengths of the negative lens and the positive lens included in the lens is maintained, and the refractive power of the entire first lens group is weakened. Zoom lens.

The zoom lens according to claim 1, wherein an aspherical surface is formed on the third surface of the first lens group and the first surface of the second lens group.

When the focal length of the first lens group is F1, the focal length of the second lens group is F2, and the focal length at the wide angle end of the entire system is Fw,
1.4 <| F1 | / F2 <1.51
And 1.5 <F2 / Fw <1.75
The zoom lens according to claim 1, wherein:

The radius of curvature of the image side surface of the positive lens included in the first lens group is R, the distance between the negative lens and the positive lens included in the first lens group is D, and the negative lens included in the first lens group is When the focal length is f1, and the focal length of the positive lens included in the first lens group is f2,
R / D ≧ 16
And 0.43 <| f1 | / f2 <0.51
The zoom lens according to claim 1, wherein:

The focal length of the first lens group is F1, the focal length of the second lens group is F2, the focal length at the wide-angle end of the entire system is Fw, and the curvature radius of the image side surface of the positive lens included in the first lens group is R, the distance between the negative lens and the positive lens included in the first lens group is D, the focal length of the negative lens included in the first lens group is f1, and the focal point of the positive lens included in the first lens group. When the distance is f2,
1.4 <| F1 | / F2 <1.51
And 1.5 <F2 / Fw <1.75
And R / D ≧ 16
And 0.43 <| f1 | / f2 <0.51
The zoom lens according to claim 1, wherein the zoom lens satisfies the following.

A first lens group having a negative refractive power and a second lens group having a positive refractive power, which are arranged in order from the object side, and
When the focal length of the first lens group is F1, the focal length of the second lens group is F2, and the focal length at the wide angle end of the entire system is Fw,
1.4 <| F1 | / F2 <1.51
And 1.5 <F2 / Fw <1.75
A zoom lens characterized by satisfying

A first lens group which is composed of at least two lenses including one negative lens and one positive lens arranged in order from the object side and has a negative refractive power as a whole, and a first lens group having a positive refractive power. Two lens groups, and
The radius of curvature of the image side surface of the positive lens included in the first lens group is R, the distance between the negative lens and the positive lens included in the first lens group is D, and the focal length of the second lens group is F2. When the focal length at the wide-angle end of the entire system is Fw,
R / D ≧ 16
And 1.5 <F2 / Fw <1.75
A zoom lens characterized by satisfying

A first lens group which is composed of at least two lenses including one negative lens and one positive lens arranged in order from the object side and has a negative refractive power as a whole, and a first lens group having a positive refractive power. Two lens groups, and
The focal length of the first lens group is F1, the focal length of the second lens group is F2, the focal length at the wide-angle end of the entire system is Fw, and the curvature radius of the image side surface of the positive lens included in the first lens group is R, the distance between the negative lens and the positive lens included in the first lens group is D, the focal length of the negative lens included in the first lens group is f1, and the focal point of the positive lens included in the first lens group. When the distance is f2,
1.4 <| F1 | / F2 <1.51
And 1.5 <F2 / Fw <1.75
And R / D ≧ 16
And 0.43 <| f1 | / f2 <0.51
A zoom lens characterized by satisfying