US 5,642,224 A · Zoom lens system with vibration reduction function · patentgrep

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Abstract

A zoom lens system with vibration reduction function includes, in succession from the object side, a first lens unit having positive refractive power, a second lens unit movable along a direction across the optical axis thereof and having negative refractive power, a third lens unit, a fourth lens unit having positive refractive power, a fifth lens unit having negative refractive power, during the focal-length change from the wide angle end to the telephoto end, the spacing between the first lens unit and the second lens unit being increased, the spacing between the second lens unit and the third lens unit being varied, and the spacing between the fourth lens unit and the fifth lens unit being decreased, and a vibration reduction device for moving the second lens unit along the direction across the optical axis, the stabilization of an image on an image plane being accomplished by the movement of the second lens unit caused by the vibration reduction device.

Claims75

Dependent claims

A zoom lens system with vibration reduction function including, in succession from an object side:

a first lens unit having positive refractive power;
a second lens unit movable along a direction across an optical axis thereof and having negative refractive power;
a third lens unit;
a fourth lens unit having positive refractive power;
a fifth lens unit having negative refractive power;
during a focal-length change from the wide angle end to the telephoto end, spacing between said first lens unit and said second lens unit being increased, spacing between said second lens unit and said third lens unit being varied, and spacing between said fourth lens unit and said fifth lens unit being decreased;
a vibration reduction device for moving said second lens unit in the direction across said optical axis;
the stabilization of an image on an image plane being accomplished by the movement of said second lens unit caused by said vibration reduction device;
and
wherein the following condition is satisfied:
0. 3<f1/(fW.multidot.fT).sup.1/2 <1.5,
where
f1:
the focal length of said first lens unit;
fW:
the focal length of the whole zoom lens system at said wide angle end;
fT:
the focal length of the whole zoom lens system at said telephoto end, and
wherein said second lens unit includes a cemented lens component having, in succession from the object side, a concave lens element and a convex lens element, and satisfies the following condition:
N+<1.55,
where N+ is the refractive index of said convex lens element.

18 more elements

A zoom lens system with vibration reduction function including, in succession from an object side:

a first lens unit having positive refractive power;
a second lens unit movable along a direction across an optical axis thereof and having negative refractive power;
a third lens unit;
a fourth lens unit having positive refractive power;
a fifth lens unit having negative refractive power;
during a focal-length change from the wide angle end to the telephoto end, spacing between said first lens unit and said second lens unit being increased, spacing between said second lens unit and said third lens unit being varied, and spacing between said fourth lens unit and said fifth lens unit being decreased;
a vibration reduction device for moving said second lens unit in the direction across said optical axis;
the stabilization of an image on an image plane being accomplished by the movement of said second lens unit caused by said vibration reduction device;
and
wherein the following condition is satisfied:
0. 3<.vertline.f2.vertline./f1<5,
where f1 is the focal length of said first lens unit, and f2 is the focal length of said second lens unit, and
wherein said second lens unit includes a cemented lens component having, in succession from the object side, a concave lens element and a convex lens element, and satisfies the following condition:
N+<1.55,
where N+ is the refractive index of said convex lens element.

12 more elements

A zoom lens system with vibration reduction function including, in succession from an object side:

a first lens unit having positive refractive power;
a second lens unit movable along a direction across an optical axis thereof and having negative refractive power;
a third lens unit;
a fourth lens unit having positive refractive power;
a fifth lens unit having negative refractive power;
during a focal-length change from the wide angle end to the telephoto end, spacing between said first lens unit and said second lens unit being increased, spacing between said second lens unit and said third lens unit being varied, and spacing between said fourth lens unit and said fifth lens unit being decreased;
a vibration reduction device for moving said second lens unit in the direction across said optical axis;
the stabilization of an image on an image plane being accomplished by the movement of said second lens unit caused by said vibration reduction device;
and
wherein the following condition is satisfied:
.DELTA.S/.vertline.f2.vertline.<0.1,
where
f2:
the focal length of said second lens unit;
.DELTA.S:
a maximum amount of displacement which can be assumed by said second lens unit for the stabilization of said image, and
wherein said second lens unit includes a cemented lens component having, in succession from the object side, a concave lens element and a convex lens element, and satisfies the following condition:
N+<1.55,
where N+ is the refractive index of said convex lens element.

16 more elements

A zoom lens system with vibration reduction function including, in succession from an object side:

a second lens unit movable along a direction across an optical axis thereof and having negative refractive power;
a third lens unit;
a fourth lens unit having positive refractive power;
a fifth lens unit having negative refractive power;
during a focal-length change from the wide angle end to the telephoto end, spacing between said first lens unit and said second lens unit being increased, spacing between said second lens unit and said third lens unit being varied, and spacing between said fourth lens unit and said fifth lens unit being decreased;
a vibration reduction device for moving said second lens unit in the direction across said optical axis;
the stabilization of an image on an image plane being accomplished by the movement of said second lens unit caused by said vibration reduction device;
and
wherein the following condition is satisfied:
0.2<R21/f2<20,
where
f2:
the focal length of said second lens unit;
R21:
the radius of curvature of that lens surface in said second lens unit which is positioned most adjacent to the object side, and
wherein said second lens unit includes a cemented lens component having, in succession from the object side, a concave lens element and a convex lens element, and satisfies the following condition:
N+<1.55,
where N+ is the refractive index of said convex lens element.

15 more elements

A zoom lens system with vibration reduction function including, in succession from an object side:

a first lens unit having positive refractive power;
a second lens unit movable along a direction across an optical axis thereof and having negative refractive power;
a third lens unit;
a fourth lens unit having positive refractive power;
a fifth lens unit having negative refractive power;
during a focal-length change from the wide angle end to the telephoto end, spacing between said first lens unit and said second lens unit being increased, spacing between said second lens unit and said third lens unit being varied, and spacing between said fourth lens unit and said fifth lens unit being decreased;
a vibration reduction device for moving said second lens unit in the direction across said optical axis;
the stabilization of an image on an image plane being accomplished by the movement of said second lens unit caused by said vibration reduction device;
and
wherein the following condition is satisfied:
0.3<f1/(fW.multidot.fT).sup.1/2 <1.5,
where
f1:
the focal length of said first lens unit;
fW:
the focal length of the whole zoom lens system at said wide angle end;
fT:
the focal length of the whole zoom lens system at said telephoto end, and
wherein said second lens unit includes a cemented lens component having, in succession from the object side, a concave lens element and a convex lens element, and satisfies the following condition:
-2<q<0
q=(rb+ra)/(rb-ra)
where ra is the radius of curvature of the object side lens surface of said cemented lens component, and rb is the radius of curvature of the image side lens surface of said cemented lens component.

19 more elements

A zoom lens system with vibration reduction function including, in succession from an object side:

a first lens unit having positive refractive power;
a second lens unit movable along a direction across an optical axis thereof and having negative refractive power;
a third lens unit;
a fourth lens unit having positive refractive power;
a fifth lens unit having negative refractive power;
during a focal-length change from the wide angle end to the telephoto end, spacing between said first lens unit and said second lens unit being increased, spacing between said second lens unit and said third lens unit being varied, and spacing between said fourth lens unit and said fifth lens unit being decreased;
a vibration reduction device for moving said second lens unit in the direction across said optical axis;
the stabilization of an image on an image plane being accomplished by the movement of said second lens unit caused by said vibration reduction device;
and
wherein the following condition is satisfied:
0. 3<.vertline.f2.vertline./f1<5,
where f1 is the focal length of said first lens unit, and f2 is the focal length of said second lens unit, and
wherein said second lens unit includes a cemented lens component having, in succession from the object side, a concave lens element and a convex lens element, and satisfies the following condition:
-2<q-0
q=(rb+ra)/(rb-ra)
where ra is the radius of curvature of the object side lens surface of said cemented lens component, and rb is the radius of curvature of the image side lens surface of said cemented lens component.

13 more elements

A zoom lens system with vibration reduction function including, in succession from an object side:

a first lens unit having positive refractive power;
a second lens unit movable along a direction across an optical axis thereof and having negative refractive power;
a third lens unit;
a fourth lens unit having positive refractive power;
a fifth lens unit having negative refractive power;
during a focal-length change from the wide angle end to the telephoto end, spacing between said first lens unit and said second lens unit being increased, spacing between said second lens unit and said third lens unit being varied, and spacing between said fourth lens unit and said fifth lens unit being decreased;
a vibration reduction device for moving said second lens unit in the direction across said optical axis;
the stabilization of an image on an image plane being accomplished by the movement of said second lens unit caused by said vibration reduction device;
and
wherein the following condition is satisfied:
.DELTA.S/.vertline.f2<0.1,
where
f2:
the focal length of said second lens unit;
.DELTA.S:
a maximum amount of displacement which can be assumed by said second lens unit for the stabilization of said image, and
wherein said second lens unit includes a cemented lens component having, in succession from the object side, a concave lens element and a convex lens element, and satisfies the following condition:
-<
q<0
q=(rb+ra)/(rb-ra)
where ra is the radius of curvature of the object side lens surface of said cemented lens component, and rb is the radius of curvature of the image side lens surface of said cemented lens component.

18 more elements

A zoom lens system with vibration reduction function including, in succession from an object side:

a first lens unit having positive refractive power;
a second lens unit movable along a direction across an optical axis thereof and having negative refractive power;
a third lens unit;
a fourth lens unit having positive refractive power;
a fifth lens unit having negative refractive power;
during a focal-length change from the wide angle end to the telephoto end, spacing between said first lens unit and said second lens unit being increased, spacing between said second lens unit and said third lens unit being varied, and spacing between said fourth lens unit and said fifth lens unit being decreased;
a vibration reduction device for moving said second lens unit in the direction across said optical axis;
the stabilization of an image on an image plane being accomplished by the movement of said second lens unit caused by said vibration reduction device;
and
wherein the following condition is satisfied:
0. 2<R21/f2<20,
where
f2:
the focal length of said second lens unit;
R21:
the radius of curvature of that lens surface in said second lens unit which is positioned most adjacent to the object side, and
wherein said second lens unit includes a cemented lens component having, in succession from the object side, a concave lens element and a convex lens element, and satisfies the following condition:
-2<q<0
q=(rb+ra)/(rb-ra)
where ra is the radius of curvature of the object side lens surface of said cemented lens component, and rb is the radius of curvature of the image side lens surface of said cemented lens component.

17 more elements

Dependencies are inferred from the claim text.