Zoom lens and image pickup apparatus using the same

1. A zoom lens 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; and

a fourth lens unit having a positive refractive power,

wherein

the zoom lens satisfies the following conditional expressions (3), (4), (5), and (6)

Σ d 1G /f t <0.13  (3)

Σ d 1G /Σd 3G <0.5  (4)

2.1 <f 3 /f w   (5)

0.2 <L/I   (6)

where,

Σd 1G denotes a sum total of an optical axial thickness of the first lens unit,

f t denotes a focal length at a telephoto end of the overall zoom lens system,

Σd 3G denotes a sum total of an optical axial thickness of the third lens unit,

f 3 denotes a focal length of the third lens unit,

f w denotes a focal length at a wide angle end of the overall zoom lens system,

L denotes an optical axial thickness of optical members which form the first lens unit, and

I denotes a maximum image height at the wide angle end of the overall zoom lens system.

2. A zoom lens 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; and

a fourth lens unit having a positive refractive power,

wherein

the first lens unit consists one positive lens, and

the zoom lens satisfies the following conditional expressions (7) and (8)

65 <v d — 1G   (7)

0.1<(β 2t /β 2w )/(β 3t /β 3w )<0.483  (8)

where,

v d 1G denotes Abbe's number (n d1 −1)/(n F1 −n C1 ) for a d-line of the first lens unit,

n d1 denotes a refractive index for the d-line of the first lens unit,

n F1 denotes a refractive index for an F-line of the first lens unit,

n C1 denotes a refractive index for a C-line of the first lens unit,

β 2t denotes a lateral magnification at a telephoto end of the second lens unit

β 2w denotes a lateral magnification at a wide angle end of the second lens unit,

β 3t denotes a lateral magnification at the telephoto end of the third lens unit, and

β 3w denotes a lateral magnification at the wide angle end of the third lens unit.

3. A zoom lens 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; and

a fourth lens unit having a positive refractive power,

wherein

the first lens unit consists one positive lens, and

the zoom lens satisfies the following conditional expressions (7a) and (8a)

71 <v d 1G   (7a)

0.1<(β 2t /(β 2w )/(β 3t /(β 3w )<0.6  (8a)

where,

v d 1G denotes Abbe's number (n d1 −1)/(n F1 −n C1 ) for a d-line of the first lens unit,

n d1 denotes a refractive index for the d-line of the first lens unit,

n F1 denotes a refractive index for an F-line of the first lens unit,

n C1 denotes a refractive index for a C-line of the first lens unit,

β 2t denotes a lateral magnification at a telephoto end of the second lens unit

β 2w denotes a lateral magnification at a wide angle end of the second lens unit,

β 3t denotes a lateral magnification at the telephoto end of the third lens unit, and

β 3w denotes a lateral magnification at the wide angle end of the third lens unit.

4. A zoom lens 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; and

a fourth lens unit having a positive refractive power,

wherein

the first lens unit consists one positive lens, and

the zoom lens satisfies the following conditional expressions (7) and (9)

65 <v d 1G   (7)

0.05<(β 4t /β 4w )/(β 3t /β 3w )<0.27  (9)

where,

v d 1G denotes Abbe's number (n d1 −1)/(n F1 −n C1 ) for a d-line of the first lens unit,

n d1 denotes a refractive index for the d-line of the first lens unit,

n F1 denotes a refractive index for an F-line of the first lens unit,

n C1 denotes a refractive index for a C-line of the first lens unit,

β 4t denotes a lateral magnification at a telephoto end of the fourth lens unit

β 4w denotes a lateral magnification at a wide angle end of the fourth lens unit,

β 3t denotes a lateral magnification at the telephoto end of the third lens unit, and

β 3w denotes a lateral magnification at the wide angle end of the third lens unit.

5. A zoom lens 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; and

a fourth lens unit having a positive refractive power,

wherein

the first lens unit consists one positive lens, and

the third lens unit comprises not less than three lenses, and

the zoom lens satisfies the following conditional expressions (7a) and (8b)

71 <v d 1G   (7a)

0.1<(β 2t /β 2w )/(β 3t /β 3w )<0.65  (8b)

where,

v d 1G denotes Abbe's number (n d1 −1)/(n F1 −n C1 ) for a d-line of the first lens unit,

n d1 denotes a refractive index for the d-line of the first lens unit,

n F1 denotes a refractive index for an F-line of the first lens unit,

n C1 denotes a refractive index for a C-line of the first lens unit,

β 2t denotes a lateral magnification at a telephoto end of the second lens unit

β 2w denotes a lateral magnification at a wide angle end of the second lens unit,

β 3t denotes a lateral magnification at the telephoto end of the third lens unit, and

β 3w denotes a lateral magnification at the wide angle end of the third lens unit.

6. A zoom lens 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; and

a fourth lens unit having a positive refractive power,

wherein

the first lens unit consists one positive lens, and

the zoom lens satisfies the following conditional expressions (7a), (8c), and (10)

71 <v d 1G (7a)

0.1<(β 2t /β 2w )/(β 3t /β 3w )<0.62  (8c)

0.7<(β 3t /β 3w )/(f t /f w )<1.1  (10)

where,

v d 1G denotes Abbe's number (n d1 −1)/(n F1 −n C1 ) for a d-line of the first lens unit,

n d1 denotes a refractive index for the d-line of the first lens unit,

n F1 denotes a refractive index for an F-line of the first lens unit,

n C1 denotes a refractive index for a C-line of the first lens unit,

β 2t denotes a lateral magnification at a telephoto end of the second lens unit

β 2w denotes a lateral magnification at a wide angle end of the second lens unit,

β 3t denotes a lateral magnification at the telephoto end of the third lens unit,

β 3w denotes a lateral magnification at the wide angle end of the third lens unit,

f t denotes a focal length at the telephoto end of the overall zoom lens system, and

f w denotes a focal length at the wide angle end of the overall zoom lens system.

7. A zoom lens 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; and

a fourth lens unit having a positive refractive power,

wherein

the first lens unit consists one positive lens, and

at the time of zooming from a wide angle end to a telephoto end, the fourth lens unit moves toward the object side, and

the zoom lens satisfies the following conditional expressions (7a), (10), and (11)

71 <v d 1G   (7a)

0.7<(β 3t /β 3w )/(f t /f w )<1.1  (10)

0.1<(Δ 1G /f 1 )/(Δ 4G /f 4 )<1.9  (11)

where,

v d 1G denotes Abbe's number (n d1 −1)/(n F1 −n C1 ) for a d-line of the first lens unit,

n d1 denotes a refractive index for the d-line of the first lens unit,

n F1 denotes a refractive index for an F-line of the first lens unit,

n C1 denotes a refractive index for a C-line of the first lens unit,

β 3t denotes a lateral magnification at the telephoto end of the third lens unit,

β 3w denotes a lateral magnification at the wide angle end of the third lens unit,

f t denotes a focal length at the telephoto end of the overall zoom lens system,

f w denotes a focal length at the wide angle end of the overall zoom lens system,

f 4 denotes a focal length of the fourth lens unit,

Δ 4G denotes an amount of movement of the fourth lens unit at the telephoto end with respect to the wide angle end,

f 1 denotes a focal length of the first lens unit, and

Δ 1G denotes an amount of movement of the first lens unit at the telephoto end with respect to the wide angle end.

8. A zoom lens 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; and

a fourth lens unit having a positive refractive power,

wherein

the first lens unit consists one positive lens, and

the zoom lens satisfies the following conditional expressions (7) and (12)

65 <v d 1G   (7)

3<β 3t /β 3w   (12)

where,

v d 1G denotes Abbe's number (n d1 −1)/(n F1 −n C1 ) for a d-line of the first lens unit,

n d1 denotes a refractive index for the d-line of the first lens unit,

n F1 denotes a refractive index for an F-line of the first lens unit,

n C1 denotes a refractive index for a C-line of the first lens unit,

β 3t denotes a lateral magnification at a telephoto end of the third lens unit, and

β 3w denotes a lateral magnification at the wide angle end of the third lens unit.

9. A zoom lens comprising in order from an object side:

a first lens unit having a positive refractive power,

wherein

the first lens unit having a positive refractive power consists one positive lens, and

the zoom lens satisfies the following conditional expressions (1) and (2),

Fno (W) <2.7  (1)

3.1 <f t /f w   (2)

where

Fno (W) denotes an F-number of the zoom lens at a wide angle end,

f t denotes a focal length at a telephoto end of the overall zoom lens s stem and

f w denotes a focal length at the wide angle end of the overall zoom lens system;

and wherein the zoom lens satisfies the following conditional expression (13)

Fno (T) <4.1  (13)

where,

Fno (T) denotes an F-number of the zoom lens at a telephoto end.

10. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression (9)

0.05<(β 4t /β 4w )/(β 3t /β 3w )<0.27  (9)

where,

β 4t denotes a lateral magnification at the telephoto end of the fourth lens unit

β 4w denotes a lateral magnification at the wide angle end of the fourth lens unit,

β 3t denotes a lateral magnification at the telephoto end of the third lens unit, and

β 3w denotes a lateral magnification at the wide angle end of the third lens unit.

11. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression (10)

0.7<(β 3t /β 3w )/(f t /f w )<1.1  (10)

where,

β 3t denotes a lateral magnification at the telephoto end of the third lens unit,

β 3w denotes a lateral magnification at the wide angle end of the third lens unit,

f t denotes the focal length at the telephoto end of the overall zoom lens system, and

f w denotes the focal length at the wide angle end of the overall zoom lens system.

12. The zoom lens according to claim 1 , wherein

at the time of zooming from the wide angle end to the telephoto end, the fourth lens unit moves toward the object side, and

the zoom lens satisfies the following conditional expression (11)

0.1<(Δ 1G /f 1 )/(Δ 4G /f 4 )<1.9  (11)

where,

f 4 denotes a focal length of the fourth lens unit,

Δ 4G denotes an amount of movement of the fourth lens unit at the telephoto end with respect to the wide angle end,

f 1 denotes a focal length of the first lens unit, and

Δ 1G denotes an amount of movement of the first lens unit at the telephoto end with respect to the wide angle end.

13. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression (15)

β 4(T) <0.7  (15)

where,

β 4(T) denotes a lateral magnification at the telephoto end of the fourth lens unit.

14. The zoom lens according to claim 1 , wherein at the time of zooming from the wide angle end to the telephoto end, an aperture stop moves integrally with the third lens unit.

15. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression (17)

−1 <f 2 /f 3 <−0.6  (17)

where,

f 2 denotes a focal length of the second lens unit, and

f 3 denotes a focal length of the third lens unit.

16. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression (18)

0.45 <f 3 /f t <0.7  (18)

where,

f 3 denotes the focal length of the third lens unit, and

f t denotes the focal length at the telephoto end of the overall zoom lens system.

17. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression (18)

−0.6 <f 2 /f t <−0.3  (19)

where,

f 2 denotes a focal length of the second lens unit, and

f t denotes a focal length at the telephoto end of the overall zoom lens system.

18. The zoom lens according to claim 1 , wherein

the third lens unit comprises in order from the object side, a first lens component having a positive refractive power and a second lens component having a negative refractive power, and

the zoom lens satisfies the following conditional expression (20)

0.1 <|f —3G1 /f —3G2 |<0.63  (20)

where,

f —3G1 denotes a focal length of the first lens component in the third lens unit, and

f —3G2 denotes a focal length of the second lens component in the third lens unit.

19. The zoom lens according to claim 18 , wherein

the second lens component is a cemented lens of a positive lens and a negative lens, and

the zoom lens satisfies the following conditional expression (21)

1.4 <|f —3G2-p /f —3G2-n |<1.9  (21)

where,

f —3G2-p denotes a focal length of the positive lens of the second lens component in the third lens unit, and

f —3G2-n denotes a focal length of the negative lens of the second lens component in the third lens unit.

20. The zoom lens according to claim 19 , wherein the zoom lens satisfies the following conditional expression (22)

−0.05≦( n d — 3G2-p )−( n d — 3G2-n )  (22)

where,

n d — 3G2-p denotes a refractive index of the positive lens of the second lens component in the third lens unit, and

n d — 3G2-n denotes a refractive index of the negative lens of the second lens component in the third lens unit.