Zoom lens system and image pickup apparatus using the same

Abstract

A zoom lens system includes, in order from an object side: a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power; and in a telephoto end as compared with a wide-angle end, a space between the first lens unit and the second lens unit increases, a space between the second lens unit and the third lens unit decreases, and a space between the third lens unit and the fourth lens unit changes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given below and the accompanying drawings, which are given by way of illustration only and thus are not limitative of the present invention, wherein:

FIGS. 1A to 1E are sectional views of Example 1 of the present invention along an optical axis, FIG. 1A shows an arrangement of lens units in a wide-angle end, FIGS. 1B, 1C and 1D show arrangements of the lens units in three states between the wide-angle end and a telephoto end, and FIG. 1E shows an arrangement of the lens units in the telephoto end;

FIGS. 2A to 2C are aberration diagrams showing a spherical aberration (SA), astigmatism (FC), distortion (DT) and chromatic aberration of magnification (CC) of Example 1 when focused on an infinite object, FIG. 2A shows the aberrations in the wide-angle end, FIG. 2B shows the aberrations in the state shown in FIG. 1C, and FIG. 2C shows the aberrations in the telephoto end;

FIGS. 3A to 3E are sectional views of Example 2 of the present invention along an optical axis, FIG. 3A shows an arrangement of lens units in a wide-angle end, FIGS. 3B, 3C and 3D show arrangements of the lens units in three states between the wide-angle end and a telephoto end, and FIG. 3E shows an arrangement of the lens units in the telephoto end;

FIGS. 4A to 4C are aberration diagrams showing a spherical aberration (SA), astigmatism (FC), distortion (DT) and chromatic aberration of magnification (CC) of Example 2 when focused on an infinite object, FIG. 4A shows the aberrations in the wide-angle end, FIG. 4B shows the aberrations in the state shown in FIG. 3C, and FIG. 4C shows the aberrations in the telephoto end;

FIGS. 5A to 5E are sectional views of Example 3 of the present invention along an optical axis, FIG. 5A shows an arrangement of lens units in a wide-angle end, FIGS. 5B, 5C and 5D show arrangements of the lens units in three states between the wide-angle end and a telephoto end, and FIG. 5E shows an arrangement of the lens units in the telephoto end;

FIGS. 6A to 6C are aberration diagrams showing a spherical aberration (SA), astigmatism (FC), distortion (DT) and chromatic aberration of magnification (CC) of Example 3 when focused on an infinite object, FIG. 6A shows the aberrations in the wide-angle end, FIG. 6B shows the aberrations in the state shown in FIG. 5C, and FIG. 6C shows the aberrations in the telephoto end;

FIGS. 7A to 7E are sectional views of Example 4 of the present invention along an optical axis, FIG. 7A shows an arrangement of lens units in a wide-angle end, FIGS. 7B, 7C and 7D show arrangements of the lens units in three states between the wide-angle end and a telephoto end, and FIG. 7E shows an arrangement of the lens units in the telephoto end;

FIGS. 8A to 8C are aberration diagrams showing a spherical aberration (SA), astigmatism (FC), distortion (DT) and chromatic aberration of magnification (CC) of Example 4 when focused on an infinite object, FIG. 8A shows the aberrations in the wide-angle end, FIG. 8B shows the aberrations in the state shown in FIG. 7C, and FIG. 8C shows the aberrations in the telephoto end;

FIGS. 9A to 9E are sectional views of Example 5 of the present invention along an optical axis, FIG. 9A shows an arrangement of lens units in a wide-angle end, FIGS. 9B, 9C and 9D show arrangements of the lens units in three states between the wide-angle end and a telephoto end, and FIG. 9E shows an arrangement of the lens units in the telephoto end;

FIGS. 10A to 10C are aberration diagrams showing a spherical aberration (SA), astigmatism (FC), distortion (DT) and chromatic aberration of magnification (CC) of Example 5 when focused on an infinite object, FIG. 10A shows the aberrations in the wide-angle end, FIG. 10B shows the aberrations in the state shown in FIG. 9C, and FIG. 10C shows the aberrations in the telephoto end;

FIGS. 11A to 11E are sectional views of Example 6 of the present invention along an optical axis, FIG. 11A shows an arrangement of lens units in a wide-angle end, FIGS. 11B, 11C and 11D show arrangements of the lens units in three states between the wide-angle end and a telephoto end, and FIG. 11E shows an arrangement of the lens units in the telephoto end;

FIGS. 12A to 12C are aberration diagrams showing a spherical aberration (SA), astigmatism (FC), distortion (DT) and chromatic aberration of magnification (CC) of Example 6 when focused on an infinite object, FIG. 12A shows the aberrations in the wide-angle end, FIG. 12B shows the aberrations in the state shown in FIG. 11C, and FIG. 12C shows the aberrations in the telephoto end;

FIGS. 13A to 13E are sectional views of Example 7 of the present invention along an optical axis, FIG. 13A shows an arrangement of lens units in a wide-angle end, FIGS. 13B, 13C and 13D show arrangements of the lens units in three states between the wide-angle end and a telephoto end, and FIG. 13E shows an arrangement of the lens units in the telephoto end;

FIGS. 14A to 14C are aberration diagrams showing a spherical aberration (SA), astigmatism (FC), distortion (DT) and chromatic aberration of magnification (CC) of Example 7 when focused on an infinite object, FIG. 14A shows the aberrations in the wide-angle end, FIG. 14B shows the aberrations in the state shown in FIG. 13C, and FIG. 14C shows the aberrations in the telephoto end;

FIGS. 15A to 15E are sectional views of Example 8 of the present invention along an optical axis, FIG. 15A shows an arrangement of lens units in a wide-angle end, FIGS. 15B, 15C and 15D show arrangements of the lens units in three states between the wide-angle end and a telephoto end, and FIG. 15E shows an arrangement of the lens units in the telephoto end;

FIGS. 16A to 16E are sectional views of Example 9 of the present invention along an optical axis, FIG. 16A shows an arrangement of lens units in a wide-angle end, FIGS. 16B, 16C and 16D show arrangements of the lens units in three states between the wide-angle end and a telephoto end, and FIG. 16E shows an arrangement of the lens units in the telephoto end;

FIGS. 17A to 17E are sectional views of Example 10 of the present invention along an optical axis, FIG. 17A shows an arrangement of lens units in a wide-angle end, FIGS. 17B, 17C and 17D show arrangements of the lens units in three states between the wide-angle end and a telephoto end, and FIG. 17E shows an arrangement of the lens units in the telephoto end;

FIGS. 18A to 18E are sectional views of Example 11 of the present invention along an optical axis, FIG. 18A shows an arrangement of lens units in a wide-angle end, FIGS. 18B, 18C and 18D show arrangements of the lens units in three states between the wide-angle end and a telephoto end, and FIG. 18E shows an arrangement of the lens units in the telephoto end;

FIGS. 19A to 19E are sectional views of Example 12 of the present invention along an optical axis, FIG. 19A shows an arrangement of lens units in a wide-angle end, FIGS. 19B, 19C and 19D show arrangements of the lens units in three states between the wide-angle end and a telephoto end, and FIG. 19E shows an arrangement of the lens units in the telephoto end;

FIGS. 20A to 20C are aberration diagrams showing a spherical aberration (SA), astigmatism (FC), distortion (DT) and chromatic aberration of magnification (CC) of Example 8 when focused on an infinite object, FIG. 20A shows the aberrations in the wide-angle end, FIG. 20B shows the aberrations in the state shown in FIG. 15C, and FIG. 20C shows the aberrations in the telephoto end;

FIGS. 21A to 21C are aberration diagrams showing a spherical aberration (SA), astigmatism (FC), distortion (DT) and chromatic aberration of magnification (CC) of Example 9 when focused on an infinite object, FIG. 21A shows the aberrations in the wide-angle end, FIG. 21B shows the aberrations in the state shown in FIG. 16C, and FIG. 21C shows the aberrations in the telephoto end;

FIGS. 22A to 22C are aberration diagrams showing a spherical aberration (SA), astigmatism (FC), distortion (DT) and chromatic aberration of magnification (CC) of Example 10 when focused on an infinite object, FIG. 22A shows the aberrations in the wide-angle end, FIG. 22B shows the aberrations in the state shown in FIG. 17C, and FIG. 22C shows the aberrations in the telephoto end;

FIGS. 23A to 23C are aberration diagrams showing a spherical aberration (SA), astigmatism (FC), distortion (DT) and chromatic aberration of magnification (CC) of Example 11 when focused on an infinite object, FIG. 23A shows the aberrations in the wide-angle end, FIG. 23B shows the aberrations in the state shown in FIG. 18C, and FIG. 23C shows the aberrations in the telephoto end;

FIGS. 24A to 24C are aberration diagrams showing a spherical aberration (SA), astigmatism (FC), distortion (DT) and chromatic aberration of magnification (CC) of Example 12 when focused on an infinitely far object, FIG. 24A shows the aberrations in the wide-angle end, FIG. 24B shows the aberrations in the state shown in FIG. 19C, and FIG. 24C shows the aberrations in the telephoto end;

FIG. 25 is a front perspective view showing an appearance of a digital camera indicating a zoom lens system according to the present invention;

FIG. 26 is a rear view of the digital camera shown in FIG. 25; and

FIGS. 27 to 29 are explanatory views showing an inner constitution of the digital camera shown in FIG. 25.

Claims

1. A zoom lens system comprising, in order from an object side: a first lens unit having a positive refractive power;a second lens unit having a negative refractive power;a third lens unit having a positive refractive power; anda fourth lens unit having a positive refractive power,wherein a space between the lens units is changed to perform magnification change from a wide-angle end to a telephoto end;the third lens unit comprises, in order from the object side, a first lens which is a positive lens element, a second lens which is a double concave negative lens element and a third lens which is a negative lens element, and the total number of the lens elements included in the third lens unit is three; andin the telephoto end as compared with the wide-angle end, a space between the first lens unit and the second lens unit increases, anda space between the second lens unit and the third lens unit decreases.

2. A zoom lens system comprising, in order from an object side: a first lens unit having a positive refractive power;a second lens unit having a negative refractive power;a third lens unit having a positive refractive power; anda fourth lens unit having a positive refractive power,wherein a space between the lens units is changed to perform magnification change from a wide-angle end to a telephoto end;the third lens unit comprises, in order from the object side, a first lens which is a positive lens element, a second lens which is a negative lens element and a third lens which is a negative meniscus lens element whose convex surface faces the object side, and the total number of the lens elements included in the third lens unit is three; andin the telephoto end as compared with the wide-angle end, a space between the first lens unit and the second lens unit increases, anda space between the second lens unit and the third lens unit decreases.

3. The zoom lens system according to claim 1, wherein the third lens of the third lens unit is a negative meniscus lens element whose convex surface faces the object side.

4. The zoom lens system according to claim 1, wherein the first lens unit and the third lens unit are arranged closer to the object side in the telephoto end than in the wide-angle end.

5. The zoom lens system according to claim 1, wherein the total number of the lens elements included in each of the first lens unit, the second lens unit and the fourth lens unit is one or two.

6. An image pickup apparatus comprising: the zoom lens system according to claim 1; andan image pickup element which is disposed on an image side of the zoom lens system and which converts an optical image formed by the zoom lens system into an electric signal.

7. A zoom lens system comprising, in order from an object side: a first lens unit having a positive refractive power;a second lens unit having a negative refractive power;a third lens unit having a positive refractive power; anda fourth lens unit having a positive refractive power,wherein the first lens unit, the second lens unit, the third lens unit and the fourth lens unit move in an optical axis direction so as to change an air space between the lens units, and perform magnification change from a wide-angle end to a telephoto end;in the telephoto end as compared with the wide-angle end, a space between the first lens unit and the second lens unit increases, anda space between the second lens unit and the third lens unit decreases;the third lens unit comprises, in order from the object side, a first lens which is a positive lens element, a second lens which is a negative lens element, a third lens which is a positive lens element and a fourth lens which is a negative lens element, and the total number of the lens elements included in the third lens unit is four; andthe second lens of the third lens unit is cemented to at least one of the first lens and the third lens on the optical axis.

8. A zoom lens system comprising, in order from an object side: a first lens unit having a positive refractive power;a second lens unit having a negative refractive power;a third lens unit having a positive refractive power; anda fourth lens unit having a positive refractive power,wherein the first lens unit, the second lens unit, the third lens unit and the fourth lens unit move in an optical axis direction so as to change an air space between the lens units, and perform magnification change from a wide-angle end to a telephoto end;in the telephoto end as compared with the wide-angle end, a space between the first lens unit and the second lens unit increases, anda space between the second lens unit and the third lens unit decreases;the third lens unit comprises, in order from the object side, a first lens which is a positive lens element, a second lens which is a negative lens element, a third lens which is a positive lens element and a fourth lens which is a negative lens element, and the total number of the lens elements of the third lens unit is four; andat least one of the second lens and the fourth lens of the third lens unit is a double concave lens.

9. The zoom lens system according to claim 7, wherein at least one of the second lens and the fourth lens of the third lens unit is a double concave lens.

10. The zoom lens system according to claim 7, wherein the first lens unit and the third lens unit are positioned closer to the object side in the telephoto end than in the wide-angle end.

11. The zoom lens system according to claim 7, wherein the total number of the lens elements included in each of the first lens unit, the second lens unit and the fourth lens unit is one or two.

12. An image pickup apparatus comprising: the zoom lens system according to claim 7;an image pickup element which is disposed on an image side of the zoom lens system and which converts an optical image formed by the zoom lens system into an electric signal.

13. A zoom lens system comprising, in order from an object side: a first lens unit having a positive refractive power;a second lens unit having a negative refractive power;a third lens unit having a positive refractive power; anda fourth lens unit having a positive refractive power,wherein during zooming from a wide-angle end to a telephoto end, a space between the first lens unit and the second lens unit increases,a space between the second lens unit and the third lens unit decreases, anda space between the third lens unit and the fourth lens unit changes;the first lens unit comprises a positive lens element, and the total number of the lens elements included in the first lens unit is one;the second lens unit comprises, in order from the object side, a negative lens element and a positive lens element, the total number of the lens elements included in the second lens unit is two, and the negative lens element of the second lens unit is a double concave negative lens element;the third lens unit comprises, in order from the object side, a positive lens element, a positive lens element and a negative lens element, and the total number of the lens elements included in the third lens unit is three; andin the telephoto end, a composite system of the second lens unit and the third lens unit has a negative composite focal length.

14. A zoom lens system comprising, in order from an object side: a first lens unit having a positive refractive power;a second lens unit having a negative refractive power;a third lens unit having a positive refractive power; anda fourth lens unit having a positive refractive power,wherein during zooming from a wide-angle end to a telephoto end, a space between the first lens unit and the second lens unit increases,a space between the second lens unit and the third lens unit decreases, anda space between the third lens unit and the fourth lens unit changes;the first lens unit comprises a positive lens element, and the total number of the lens elements included in the first lens unit is one;the second lens unit comprises, in order from the object side, a negative lens element and a positive lens element, and the total number of the lens elements included in the second lens unit is two;the third lens unit comprises, in order from the object side, a positive lens element, a positive lens element and a negative lens element, and the total number of the lens elements included in the third lens unit is three; andduring zooming from the wide-angle end to the telephoto end, all of the first lens unit to the fourth lens unit move along an optical axis, and the fourth lens unit moves on a movement track which comprises a portion being convex toward the object side.

15. A zoom lens system comprising, in order from an object side: a first lens unit having a positive refractive power;a second lens unit having a negative refractive power;a third lens unit having a positive refractive power; anda fourth lens unit having a positive refractive power,wherein during zooming from a wide-angle end to a telephoto end, a space between the first lens unit and the second lens unit increases,a space between the second lens unit and the third lens unit decreases, anda space between the third lens unit and the fourth lens unit changes;the first lens unit comprises a positive lens element, and the total number of the lens elements included in the first lens unit is one;the second lens unit comprises, in order from the object side, a negative lens element and a positive lens element, the total number of the lens elements included in the second lens unit is two, and the negative lens element of the second lens unit is a double concave negative lens element; andthe third lens unit comprises, in order from the object side, a positive lens element and a negative lens element, and the total number of the lens elements included in the third lens unit is two.

16. A zoom lens system comprising, in order from an object side: a first lens unit having a positive refractive power;a second lens unit having a negative refractive power;a third lens unit having a positive refractive power; anda fourth lens unit having a positive refractive power,wherein during zooming from a wide-angle end to a telephoto end, a space between the first lens unit and the second lens unit increases,a space between the second lens unit and the third lens unit decreases, anda space between the third lens unit and the fourth lens unit changes;the first lens unit comprises a positive lens element, and the total number of the lens elements included in the first lens unit is one;the second lens unit comprises, in order from the object side, a negative lens element and a positive lens element, and the total number of the lens elements included in the second lens unit is two; andthe third lens unit comprises, in order from the object side, a positive lens element and a double concave negative lens element, and the total number of the lens elements included in the third lens unit is two.

17. The zoom lens system according to claim 13, further comprising: an aperture stop disposed just before the third lens unit.

18. The zoom lens system according to claim 13, wherein the zoom lens system is four-unit zoom lens system.

19. The zoom lens system according to claim 13, wherein the fourth lens unit comprises a positive lens element, and the total number of the lens elements included in the fourth lens unit is one.

20. The zoom lens system according to claim 13, wherein the following condition is satisfied: 0.5<fT/fg1<2.5  (1C),

21. The zoom lens system according to claim 13, wherein the following condition is satisfied: 7<fT/fg2<−2  (2C),

22. The zoom lens system according to claim 13, wherein the following condition is satisfied: 1.8<fT/fg3<6  (3C),

23. The zoom lens system according to claim 13, wherein the following condition is satisfied: 1.5<fg1/fg3<3.0  (4C),

24. The zoom lens system according to claim 13, wherein the following condition is satisfied: 1.0<fg1/fg4<3.0  (5C),

25. The zoom lens system according to claim 13, wherein the following condition is satisfied: −0.7<fg2/fg4<−0.1  (6C),

26. The zoom lens system according to claim 13, wherein a composite system of the second lens unit and the third lens unit have a positive composite focal length in the wide-angle end; a composite system of the second lens unit and the third lens unit have a negative composite focal length in the telephoto end; andthe following condition is satisfied: −2.5<fg23W/fg23T<−0.1  (7C),

27. The zoom lens system according to claim 13, wherein the following condition is satisfied: −2.5<fg1/fg23T<−0.5  (8C),

28. The zoom lens system according to claim 13, wherein the following condition is satisfied: 1.8<β2T/β2W<4.0  (9C),

29. The zoom lens system according to claim 13, wherein the following condition is satisfied: 1.2<β3T/β3W<3.0  (10C),

30. The zoom lens system according to claim 13, wherein the following condition is satisfied: 0.85<β4T/β4W<2.0  (11C),

31. The zoom lens system according to claim 13, wherein the first lens unit is positioned closer to the object side in the telephoto end than in the wide-angle end; and the following condition is satisfied: 0.5<Dg1/D<2.0  (12C),

32. The zoom lens system according to claim 13, wherein the third lens unit is positioned closer to the object side in the telephoto end than in the wide-angle end; and the following condition is satisfied: 0.65<Dg3/D<1.5  (13C),

33. The zoom lens system according to claim 13, wherein the negative lens of the second lens unit is a double concave lens; and the following condition is satisfied: −7<r2f/r2r<−0.5  (14C),

34. The zoom lens system according to claim 13, wherein the negative lens of the third lens unit is a double concave lens; and the following condition is satisfied: −4<r3f/r3r<−0.1  (15C),

35. The zoom lens system according to claim 13, wherein the following condition is satisfied: 4.0<fT/fW<10.0  (16C),

36. The zoom lens system according to claim 15, wherein the following condition is satisfied: 2.7<fT/fW<7.0  (16C-1),

37. The zoom lens system according to claim 13, wherein the fourth lens unit is positioned closer to the object side in an intermediate focal length state than in the wide-angle end and the telephoto end; and the following condition is satisfied: 0.1<(Dg4s−Dg4max)/Ih<1.5  (17C),

38. An image pickup apparatus comprising: the zoom lens system according to claim 13; andan image pickup element which is disposed on an image side of the zoom lens system and which converts an image formed by the zoom lens system into an electric signal.