Zoom lens

Abstract

A zoom lens is provided and includes a first lens group, a second lens group, an aperture diaphragm, a third lens group, and a fourth lens group in order from the object side. The first lens group and the third lens group are fixed groups, and the second lens group and the fourth lens group are moving groups. The zoom lens has a right-angle prism in the first lens group and satisfies the specific conditions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention will appear more fully upon consideration of the exemplary embodiment of the invention, which are schematically set forth in the drawings, in which:

FIG. 1 shows a first configuration example of a zoom lens according to an exemplary embodiment of the invention and is a lens sectional view corresponding to example 1;

FIG. 2 shows a second configuration example of a zoom lens according to an exemplary embodiment of the invention and is a lens sectional view corresponding to example 2;

FIG. 3 shows a third configuration example of a zoom lens according to an exemplary embodiment of the invention and is a lens sectional view corresponding to example 3;

FIG. 4 is a drawing to show lens data of a zoom lens according to example 1; (A) shows lens data and (B) shows data of spacing of portion moving with variable power;

FIG. 5 is a drawing to show data concerning aspheric surfaces of a zoom lens according to example 1;

FIG. 6 is a drawing to show lens data of a zoom lens according to example 2; (A) shows lens data and (B) shows data of spacing of portion moving with variable power;

FIG. 7 is a drawing to show data concerning aspheric surfaces of a zoom lens according to example 2;

FIG. 8 is a drawing to show lens data of a zoom lens according to example 3; (A) shows lens data and (B) shows data of spacing of portion moving with variable power;

FIG. 9 is a drawing to show data concerning aspheric surfaces of a zoom lens according to example 3;

FIG. 10 is a drawing to show the values concerning conditions collectively about the examples;

FIG. 11 is an aberration drawing to show aberrations and distortion of a zoom lens according to example 1 at wide angle end; (A) shows spherical aberration, (B) shows astigmatic aberration, (C) shows distortion, and (D) shows lateral color;

FIG. 12 is an aberration drawing to show aberrations and distortion of the zoom lens according to example 1 at telephoto end; (A) shows spherical aberration, (B) shows astigmatic aberration, (C) shows distortion, and (D) shows lateral color;

FIG. 13 is an aberration drawing to show aberrations and distortion of the zoom lens according to example 2 at wide angle end; (A) shows spherical aberration, (B) shows astigmatic aberration, (C) shows distortion, and (D) shows lateral color;

FIG. 14 is an aberration drawing to show aberrations and distortion of the zoom lens according to example 2 at telephoto end; (A) shows spherical aberration, (B) shows astigmatic aberration, (C) shows distortion, and (D) shows lateral color;

FIG. 15 is an aberration drawing to show aberrations and distortion of the zoom lens according to example 3 at wide angle end; (A) shows spherical aberration, (B) shows astigmatic aberration, (C) shows distortion, and (D) shows lateral color; and

FIG. 16 is an aberration drawing to show aberrations and distortion of the zoom lens according to example 3 at telephoto end; (A) shows spherical aberration, (B) shows astigmatic aberration, (C) shows distortion, and (D) shows lateral color.

Claims

1. A zoom lens comprising: in order from an object side of the zoom lens, a first lens group having a positive refractive power;a second lens group having a negative refractive power;an aperture diaphragm;a third lens group having a positive refractive power; anda fourth lens group having a positive refractive power,whereinthe first lens group and the third lens group are fixed when the zoom lens varies a power thereof and is focused, the second lens group moves along an optical axis thereof when the zoom lens varies the power thereof, and the fourth lens group moves along an optical axis thereof when the zoom lens varies a power thereof and is focused,the first lens group comprises: in order from the object side, a first lens having a negative refractive power; a right-angle prism having an internal reflection face for bending an optical path approximately 90°; a second lens having a positive refractive power; and a third lens having positive refractive power, andthe first lens group satisfies Conditions: 1.71<Np<1.80  (1)νp>30  (2)1.4<D2-6/fw<1.9  (3)

2. The zoom lens as claimed in claim 1, wherein the right-angle prism satisfies Condition: τ10P>0.87  (4)

3. The zoom lens as claimed in claim 1, wherein the second lens and the third lens satisfy Condition: 1.4<f12/f13<3.2  (5)

4. The zoom lens as claimed in claim 2, wherein the second lens and the third lens satisfy Condition: 1.4<f12/f13<3.2  (5)

5. The zoom lens as claimed in claim 1, wherein each lens in the first lens group satisfies Condition: 25<ν23A−ν1<36  (6)

6. The zoom lens as claimed in claim 2, wherein each lens in the first lens group satisfies Condition: 25<ν23A−ν1<36  (6)

7. The zoom lens as claimed in claim 3, wherein each lens in the first lens group satisfies Condition: 25<ν23A−ν1<36  (6)

8. The zoom lens as claimed in claim 4, wherein each lens in the first lens group satisfies Condition: 25<ν23A−ν1<36  (6)

9. The zoom lens as claimed in claim 1, wherein the third lens group consists of a plastic lens having an aspheric surface.

10. The zoom lens as claimed in claim 2, wherein the third lens group consists of a plastic lens having at least one aspheric surface.

11. The zoom lens as claimed in claim 3, wherein the third lens group consists of a plastic lens having at least one aspheric surface.

12. The zoom lens as claimed in claim 4, wherein the third lens group consists of a plastic lens having at least one aspheric surface.

13. The zoom lens as claimed in claim 5, wherein the third lens group consists of a plastic lens having at least one aspheric surface.

14. The zoom lens as claimed in claim 6, wherein the third lens group consists of a plastic lens having at least one aspheric surface.

15. The zoom lens as claimed in claim 7, wherein the third lens group consists of a plastic lens having at least one aspheric surface.

16. The zoom lens as claimed in claim 8, wherein the third lens group consists of a plastic lens having at least one aspheric surface.