Zoom lens system with vibration reduction function

Abstract

Providing a compact zoom lens system suitable for a single-lens reflex camera using a solid-state imaging device, having a zoom ratio of about 3.5 or more, an angle of view of 29° or more in a wide-angle end, and a vibration reduction function. The system includes, in order from an object, a first group having positive power, a second group having negative power, and a third group having positive power. Upon zooming from a wide-angle end to a telephoto end, a distance between the first and second groups increases, and a distance between the second and third groups decreases. The third group consists of, in order from the object, a 31 group having positive power, a 32 group having negative power, and a 33 group. Only the 32 group is moved perpendicularly to an optical axis for correcting an image blur upon generating a camera shake. Given conditions are satisfied.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing an imaging apparatus using a zoom lens system with a vibration reduction function according to the present application.

FIG. 2 is a diagram showing a lens configuration of a zoom lens system with a vibration reduction function according to Example 1.

FIGS. 3A and 3B are graphs showing various aberrations of the zoom lens system with a vibration reduction function according to Example 1 in a wide-angle end state focusing on infinity in which FIG. 3A shows various aberrations without carrying out vibration reduction, and FIG. 3B shows coma upon correcting a rotational camera shake of 0.30 degrees.

FIG. 4 is a graph showing various aberrations of the zoom lens system with a vibration reduction function according to Example 1 in an intermediate focal length state upon focusing on infinity.

FIGS. 5A and 5B are graphs showing various aberrations of the zoom lens system with a vibration reduction function according to Example 1 in a telephoto end state focusing on infinity in which FIG. 5A shows various aberrations without carrying out vibration reduction, and FIG. 5B shows coma upon correcting a rotational camera shake of 0.15 degrees.

FIG. 6 is a diagram showing a lens configuration of a zoom lens system with a vibration reduction function according to Example 2.

FIGS. 7A and 7B are graphs showing various aberrations of the zoom lens system with a vibration reduction function according to Example 2 in a wide-angle end state focusing on infinity in which FIG. 7A shows various aberrations without carrying out vibration reduction, and FIG. 7B shows coma upon correcting a rotational camera shake of 0.30 degrees.

FIG. 8 is a graph showing various aberrations of the zoom lens system with a vibration reduction function according to Example 2 in an intermediate focal length state upon focusing on infinity.

FIGS. 9A and 9B are graphs showing various aberrations of the zoom lens system with a vibration reduction function according to Example 2 in a telephoto end state focusing on infinity in which FIG. 9A shows various aberrations without carrying out vibration reduction, and FIG. 9B shows coma upon correcting a rotational camera shake of 0.15 degrees.

FIG. 10 is a diagram showing a lens configuration of a zoom lens system with a vibration reduction function according to Example 3.

FIGS. 11A and 11B are graphs showing various aberrations of the zoom lens system with a vibration reduction function according to Example 3 in a wide-angle end state focusing on infinity in which FIG. 11A shows various aberrations without carrying out vibration reduction, and FIG. 11B shows coma upon correcting a rotational camera shake of 0.30 degrees.

FIG. 12 is a graph showing various aberrations of the zoom lens system with a vibration reduction function according to Example 3 in an intermediate focal length state upon focusing on infinity.

FIGS. 13A and 13B are graphs showing various aberrations of the zoom lens system with a vibration reduction function according to Example 3 in a telephoto end state focusing on infinity in which FIG. 13A shows various aberrations without carrying out vibration reduction, and FIG. 13B shows coma upon correcting a rotational camera shake of 0.15 degrees.

Claims

1. A zoom lens system with a vibration reduction function comprising: in order from an object, a first lens group having positive refractive power;a second lens group having negative refractive power; anda third lens group having positive refractive power,upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group increasing, and a distance between the second lens group and the third lens group decreasing,the third lens group comprising, in order from the object, a 31 lens group having positive refractive power, a 32 lens group having negative refractive power, and a 33 lens group,only the 32 lens group being moved in a direction perpendicular to an optical axis for correcting an image blur on an image plane upon generating a camera shake, andthe following conditional expression being satisfied: 0.7<d31/d32<1.69

2. The zoom lens system with a vibration reduction function according to claim 1, wherein upon zooming from the wide-angle end state to the telephoto end state, the first and third lens groups are moved to the object side.

3. The zoom lens system with a vibration reduction function according to claim 2, wherein the following conditional expression is satisfied: −4.5<f1/f2<−2.0

4. The zoom lens system with a vibration reduction function according to claim 3, wherein the following conditional expression is satisfied: 2.0<f1/f3<4.0

5. The zoom lens system with a vibration reduction function according to claim 4, wherein the first lens group comprises, in order from the object, an 11 lens group having positive refractive power, and a 12 lens group having positive refractive power, and focusing from infinity to a close object is carried out by moving only the 12 lens group to the object side, and the following conditional expression is satisfied: 1.1<ft/f12<2.0

6. The zoom lens system with a vibration reduction function according to claim 5, wherein the following conditional expression is satisfied: −2.0<f32/f33<−0.8

7. The zoom lens system with a vibration reduction function according to claim 6, wherein the following conditional expression is satisfied: 0<f3/f33<0.5

8. The zoom lens system with a vibration reduction function according to claim 1, wherein the following conditional expression is satisfied: −4.5<f1/f2<−2.0

9. The zoom lens system with a vibration reduction function according to claim 1, wherein the following conditional expression is satisfied: 2.0<f1/f3<4.0

10. The zoom lens system with a vibration reduction function according to claim 1, wherein the first lens group comprises, in order from the object, an 11 lens group having positive refractive power, and a 12 lens group having positive refractive power, and focusing from infinity to a close object is carried out by moving only the 12 lens group to the object side, and the following conditional expression is satisfied: 1.1<ft/f12<2.0

11. The zoom lens system with a vibration reduction function according to claim 1, wherein the following conditional expression is satisfied: −2.0<f32/f33<−0.8

12. The zoom lens system with a vibration reduction function according to claim 1, wherein the following conditional expression is satisfied: 0<f3/f33<0.5

13. The zoom lens system with a vibration reduction function according to claim 1, wherein an aperture stop is disposed in the vicinity of the third lens group including in the third lens group.

14. The zoom lens system with a vibration reduction function according to claim 1, wherein each lens surface is formed by a spherical surface or a plane surface.

15. An imaging apparatus including a zoom lens system which has a vibration reduction function and which comprises, in order from an object a first lens group having positive refractive power;a second lens group having negative refractive power; anda third lens group having positive refractive power,upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group increasing, and a distance between the second lens group and the third lens group decreasing,the third lens group comprising, in order from the object, a 31 lens group having positive refractive power, a 32 lens group having negative refractive power, and a 33 lens group,only the 32 lens group being moved in a direction perpendicular to an optical axis for correcting an image blur on an image plane upon generating a camera shake, andthe following conditional expression being satisfied: 0.7<d31/d32<1.69

16. A method for forming an image of an object, varying a focal length, and correcting an image blur of a zoom lens system with a vibration reduction function, the method comprising steps of: providing a zoom lens system that includes, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having positive refractive power;varying a focal length from a wide-angle end state to a telephoto end state by increasing a distance between the first lens group and the second lens group, and decreasing a distance between the second lens group and the third lens group;providing the third lens group that comprises, in order from the object, a 31 lens group having positive refractive power, a 32 lens group having negative refractive power, and a 33 lens group;satisfying the following conditional expression: 0.7<d31/d32<1.69

17. The method according to claim 16, further comprising a step of: moving the first and third lens groups to the object side upon zooming from the wide-angle end state to the telephoto end state.

18. The method according to claim 16, further comprising a step of: satisfying the following conditional expression: −4.5<f1/f2<−2.0