Zoom lens system and electronic image pickup apparatus using the same

Abstract

A zoom lens system comprising, a first negative lens unit; a second positive lens unit; and a third negative lens unit, wherein a space between the second and third lens units changes during magnification change or focusing operation; the second lens unit and the third lens unit move only to the object side during the magnification change from a wide-angle end to a telephoto end so that a space between the first and second lens units is narrower in the telephoto end than in the wide-angle end; the first lens unit comprises a negative lens and a positive lens; the second lens unit comprises at most three lenses; the third lens unit comprises a negative lens; and the following condition (1) is satisfied:

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 1C are sectional views of Example 1 of the present invention when focused on an infinite object, FIG. 1A shows a state in a wide-angle end, FIG. 1B shows an intermediate state, and FIG. 1C shows a state in a telephoto end;

FIGS. 2A to 2C are sectional views of Example 2 of the present invention when focused on an infinite object, FIG. 2A shows a state in a wide-angle end, FIG. 2B shows an intermediate state, and FIG. 2C shows a state in a telephoto end;

FIGS. 3A to 3C are sectional views of Example 3 of the present invention when focused on an infinite object, FIG. 3A shows a state in a wide-angle end, FIG. 3B shows an intermediate state, and FIG. 3C shows a state in a telephoto end;

FIGS. 4A to 4C are sectional views of Example 4 of the present invention when focused on an infinite object, FIG. 4A shows a state in a wide-angle end, FIG. 4B shows an intermediate state, and FIG. 4C shows a state in a telephoto end;

FIGS. 5A to 5C are sectional views of Example 5 of the present invention when focused on an infinite object, FIG. 5A shows a state in a wide-angle end, FIG. 5B shows an intermediate state, and FIG. 5C shows a state in a telephoto end;

FIGS. 6A to 6C are sectional views of Example 6 of the present invention when focused on an infinite object, FIG. 6A shows a state in a wide-angle end, FIG. 6B shows an intermediate state, and FIG. 6C shows a state in a telephoto end;

FIGS. 7A to 7C are sectional views of Example 7 of the present invention when focused on an infinite object, FIG. 7A shows a state in a wide-angle end, FIG. 7B shows an intermediate state, and FIG. 7C shows a state in a telephoto end;

FIGS. 8A to 8C are sectional views of Example 8 of the present invention when focused on an infinite object, FIG. 8A shows a state in a wide-angle end, FIG. 8B shows an intermediate state, and FIG. 8C shows a state in a telephoto end;

FIGS. 9A to 9C are aberration diagrams of Example 1 when focused on the infinite object, FIG. 9A shows a state in the wide-angle, FIG. 9B shows an intermediate state, and FIG. 9C shows a state in the telephoto end;

FIGS. 10A to 10C are aberration diagrams of Example 2 when focused on the infinite object, FIG. 10A shows a state in the wide-angle, FIG. 10B shows an intermediate state, and FIG. 10C shows a state in the telephoto end;

FIGS. 11A to 11C are aberration diagrams of Example 3 when focused on the infinite object, FIG. 11A shows a state in the wide-angle, FIG. 11B shows an intermediate state, and FIG. 11C shows a state in the telephoto end;

FIGS. 12A to 12C are aberration diagrams of Example 4 when focused on the infinite object, FIG. 12A shows a state in the wide-angle, FIG. 12B shows an intermediate state, and FIG. 12C shows a state in the telephoto end;

FIGS. 13A to 13C are aberration diagrams of Example 5 when focused on the infinite object, FIG. 13A shows a state in the wide-angle, FIG. 13B shows an intermediate state, and FIG. 13C shows a state in the telephoto end;

FIGS. 14A to 14C are aberration diagrams of Example 6 when focused on the infinite object, FIG. 14A shows a state in the wide-angle, FIG. 14B shows an intermediate state, and FIG. 14C shows a state in the telephoto end;

FIGS. 15A to 15C are aberration diagrams of Example 7 when focused on the infinite object, FIG. 15A shows a state in the wide-angle, FIG. 15B shows an intermediate state, and FIG. 15C shows a state in the telephoto end;

FIGS. 16A to 16C are aberration diagrams of Example 8 when focused on the infinite object, FIG. 16A shows a state in the wide-angle, FIG. 16B shows an intermediate state, and FIG. 16C shows a state in the telephoto end;

FIG. 17 is an explanatory view of a basic concept for digitally correcting a distortion of an optical image;

FIG. 18 is a diagram showing a relation between an image height and a half angle of view of an object;

FIG. 19 is a front perspective view showing an appearance of a digital camera;

FIG. 20 is a rear view of the digital camera shown in FIG. 19;

FIG. 21 is a schematic sectional view showing an inner constitution of the digital camera shown in FIG. 19; and

FIG. 22 is a block diagram of a main part of an inner circuit of the digital camera shown in FIG. 19.

Claims

1. A zoom lens system comprising, in order from an object side: a first lens unit having a negative refractive power;a second lens unit having a positive refractive power; anda third lens unit having a negative refractive power,wherein a space between the first lens unit and the second lens unit changes during magnification change, a space between the second lens unit and the third lens unit changes during the magnification change or a focusing operation;at least the second lens unit and the third lens unit move to the only object side during the magnification change from a wide-angle end to a telephoto end so that the space between the first lens unit and the second lens unit is narrower in the telephoto end than in the wide-angle end;the first lens unit comprises, in order from the object side, two lenses including a negative lens and a positive lens, the total number of the lenses included in the first lens unit is two;the second lens unit comprises at most three lenses;the third lens unit comprises a negative lens, the total number of the lenses included in the third lens unit is one; andthe following conditions (1) and (2) are satisfied: 0.7<Cj(t)/Cj(w)<1.2   (1); and1.6<β2(t)/β2(w)<2.5   (2),

2. A zoom lens system comprising, in order from an object side: a first lens unit having a negative refractive power;a second lens unit having a positive refractive power; anda third lens unit having a negative refractive power,wherein a space between the first lens unit and the second lens unit changes during magnification change, a space between the second lens unit and the third lens unit changes during the magnification change or a focusing operation;at least the second lens unit and the third lens unit move to the only object side during the magnification change from a wide-angle end to a telephoto end so that the space between the first lens unit and the second lens unit is narrower in the telephoto end than in the wide-angle end;the first lens unit comprises, in order from the object side, two lenses including a negative lens and a positive lens, the total number of the lenses included in the first lens unit is two;the second lens unit comprises at most three lenses;the third lens unit comprises a negative lens, the total number of the lenses included in the third lens unit is one; andthe following conditions (1) and (3) are satisfied: 0.7<Cj(t)/Cj(w)<1.2   (1); and1.0<{β2(t)/β2(w)}/{β3(t)/β3(w)}<2.5   (3),

3. A zoom lens system comprising, in order from an object side: a first lens unit having a negative refractive power;a second lens unit having a positive refractive power; anda third lens unit having a negative refractive power,wherein a space between the first lens unit and the second lens unit changes during magnification change, a space between the second lens unit and the third lens unit changes during the magnification change or a focusing operation;at least the second lens unit and the third lens unit move to the only object side during the magnification change from a wide-angle end to a telephoto end so that the space between the first lens unit and the second lens unit is narrower in the telephoto end than in the wide-angle end;the first lens unit comprises, in order from the object side, two lenses including a negative lens and a positive lens, the total number of the lenses included in the first lens unit is two;the second lens unit comprises at most three lenses;the third lens unit comprises a negative lens, the total number of the lenses included in the third lens unit is one; andthe following conditions (1) and (4) are satisfied: 0.7<Cj(t)/Cj(w)<1.2   (1); and1.25<|f1/f2|<1.86   (4),

4. A zoom lens system according to claim 1, wherein the following condition (3) is satisfied: 1.0<{β2(t)/β2(w)}/{β3(t)/β3(w)}<2.5   (3),

5. A zoom lens system according to claim 1, 2 or 4, wherein the following condition (4) is satisfied: 1.25<|f1/f2|<1.86   (4),

6. A zoom lens system according to claim 1, wherein only the third lens unit moves during the focusing operation.

7. A zoom lens system according to claim 1, wherein the space between the second lens unit and the third lens unit changes during the magnification change.

8. A zoom lens system according to claim 1, wherein during the magnification change from the wide-angle end to the telephoto end, the first lens unit moves to an image side and then moves to the object side.

9. A zoom lens system according to claim 1, wherein the following condition (5) is satisfied: 1.42<D1(w)/fw<1.80   (5),

10. A zoom lens system according to claim 1, wherein the third lens unit moves for focusing; and the following condition (6) is satisfied, 0.5<D2(t)/D2(w)<2.0   (6),

11. A zoom lens system according to claim 1, wherein the third lens unit moves for focusing; and the following condition (7) is satisfied: −0.3<(D2(t)−D2(w))/fw<0.25   (7),

12. A zoom lens system according to claim 1 or 11, wherein the second lens unit is constituted of two or three lenses including a positive lens and a negative lens.

13. A zoom lens system according to claim 12, wherein the second lens unit comprises a cemented triplet constituted of, in order from the object side, a positive lens, a negative lens and a positive lens.

14. A zoom lens system according to claim 12, wherein the second lens unit comprises, in order from the object side, a single lens having a positive refractive power and a cemented lens constituted of a negative lens and a positive lens in order from the object side.

15. A zoom lens system according to claim 12, wherein the second lens unit comprises, in order from the object side, a single lens having a positive refractive power and a cemented lens constituted of a positive lens and a negative lens in order from the object side.

16. A zoom lens system according to claim 12, wherein the second lens unit comprises, in order from the object side, a cemented lens constituted of a positive lens and a negative lens in order from the object side, and a single lens having a positive refractive power.

17. A zoom lens system according to claim 12, wherein the second lens unit comprises, in order from the object side, a cemented lens constituted of a positive lens and a negative lens in order from the object side.

18. A zoom lens system according to claim 12, wherein the second lens unit comprises a cemented triplet constituted of a positive lens, a negative lens and a negative lens in order from the object side.

19. A zoom lens system according to claim 1, wherein the following condition (8) is satisfied: 1.2<Cj(t)/ft<1.8   (8),

20. A zoom lens system according to claim 1, wherein the third lens unit moves for focusing; the third lens unit is a negative lens; andthe following condition (9) is satisfied: 1.5<|f3/fw|<15.0   (9),

21. A zoom lens system according to claim 1, wherein the third lens unit is a negative lens; and the following condition (10) is satisfied: 0.01<D3G/ft<0.09   (10),

22. A zoom lens system according to claim 1, wherein the third lens unit moves for focusing; the third lens unit is a negative lens; andthe following condition (B) is satisfied: −3.5<1−β3(t)2<−0.6   (B),

23. A zoom lens system according to claim 1, wherein the following condition (A) is satisfied: 2.5≦ft/fw<5.5   (A),

24. A zoom lens system according to claim 1, further comprising: an aperture stop which is disposed immediately before the second lens unit and which moves integrally with the second lens unit during the magnification change.

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

26. An image pickup apparatus according to claim 25, further comprising; a low pass filter disposed between the zoom lens system and the image sensor.