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

at the time of zooming, the first lens unit moves, and

the zoom lens satisfies the following conditional expressions (1-1a), (1-2a), and (1-3a)

0.43<(β 2T /β 2W )/(β 3T /β 3W )<0.68  (1-1a)

0.4<(Δ 1G /f 1 )/(Δ 4G /f 4 )<2.3  (1-2a)

2.1 <f 3 /f W <4.1  (1-3a)

where,

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

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

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

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

Δ 1G denotes an amount of movement of the first lens unit at the time of zooming from the wide angle end to the telephoto end,

Δ 4G denotes an amount of movement of the fourth lens unit at the time of zooming from the wide angle end to the telephoto end,

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

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

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

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

2. The zoom lens according to claim 1 , wherein the first lens unit includes a cemented lens.

3. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression (1-4)

0.12<(β 4T /β 4W )/(β 3T /β 3W )<0.4  (1-4)

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

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

4. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression (1-5)

0<Δ 1G /Δ 4G <4  (1-5)

where,

Δ 1G denotes the amount of movement of the first lens unit at the time of zooming from the wide angle end to the telephoto end, and

Δ 4G denotes the amount of movement of the fourth lens unit at the time of zooming from the wide angle end to the telephoto end.

5. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression (1-6)

1.4 <|f 2 /f W |<3  (1-6)

where,

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

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

6. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression (1-7)

0.3 <|f 2 /f 3 |<1.5  (1-7)

where,

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

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

7. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression (1-8)

L T /f T <3.3  (1-8)

where,

L T denotes a total length of the overall zoom lens system at the telephoto end, and

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

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

Σ d 3G /f T <0.5  (1-9)

where,

Σd 3G denotes a total length of the third lens unit, and

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

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

3.1 <f T /f W <10  (1-10)

where,

f W denotes the focal length of the overall zoom lens system at the wide angle end, and

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

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

1.3 <|f 3 — 2 /f 3 — 1 |<5  (1-11)

wherein,

f 3 — 1 denotes a focal length of a lens component nearest to the object side, from among two or more than two lens components in the third lens unit, and

f 3 — 2 denotes a focal length of a lens component on the object side next to the lens component nearest to the object side, from among the two or more than two lens components in the third lens unit.

11. The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression (1-12)

0.6 <f 3 — 1 /f 3 <1.2  (1-12)

where,

f 3 — 1 denotes a focal length of a lens component nearest to the object side, from among two or more than two lens components in the third lens unit, and

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

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

0.9 <|f 3 — 2 /f 3 |<4  (13)

where,

f 3 — 2 denotes a focal length of a lens component on the object side next to the lens component nearest to the object side, from among two or more than two lens components in the third lens unit, and

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

13. An image pickup apparatus comprising:

a zoom lens; and

an image pickup element which includes an image pickup surface which is disposed on an image side of the zoom lens, and which receives an image formed by the zoom lens, wherein

the zoom lens is a zoom lens according to claim 1 .

14. 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

at the time of zooming, the first lens unit moves, and

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

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

0.2<(β 2T /β 2W )/(β 3T /β 3W )<0.8  (1-1b)

0<(Δ 1G /f 1 )/(Δ 4G /f 4 )<1.5  (1-2b)

where,

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

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

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

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

Δ 1G denotes an amount of movement of the first lens unit at the time of zooming from the wide angle end to the telephoto end,

Δ 4G denotes an amount of movement of the fourth lens unit at the time of zooming from the wide angle end to the telephoto end,

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

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

15. The zoom lens according to claim 14 , wherein the zoom lens satisfies the following condition (1-3b)

1.8 <f 3 /f W <4.1  (1-3b)

where,

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

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

16. 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; and

a third lens unit having a positive refractive power,

wherein

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

the zoom lens satisfies the following conditional expressions (2-1), (2-2), and (2-3)

2 <|f 3 — 2 /f 3 — 1 |<5  (2-1)

0.1<(β 2T /β 2W )/(β 3T /β 3W )<0.8  (2-2)

Fno ( W )<2.5  (2-3)

where,

f 3 — 1 denotes a focal length of the first lens component in the third lens unit,

f 3 — 2 denotes a focal length of the second lens component in the third lens unit,

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

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

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

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

Δ 1G denotes an amount of movement of the first lens unit at the time of zooming from the wide angle end to the telephoto end,

Δ 4G denotes an amount of movement of the fourth lens unit at the time of zooming from the wide angle end to the telephoto end, and

Fno (W) denotes F number at a wide angle end.

17. The zoom lens according to claim 16 , wherein the zoom lens satisfies the following conditional expression (2-4)

1.9 <f 3 /f W <5  (2-4)

where,

f 3 denotes a focal length of the third lens unit, and f W denotes a focal length of the overall zoom lens system at the wide angle end.

18. The zoom lens according to claim 16 , wherein the zoom lens satisfies the following conditional expression (2-5)

Σ d 3G /f T <0.42  (2-5)

Σd 3G denotes a total length of the third lens unit,

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

19. The zoom lens according to claim 16 , wherein the zoom lens satisfies the following conditional expression (2-6)

0.6 <|f 3 — 1 /f 3 |<1.2  (2-6)

where,

f 3 — 1 denotes a focal length of the first lens component in the third lens unit, and

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

20. The zoom lens according to claim 16 , wherein the zoom lens satisfies the following conditional expression (2-7)

0.9 <|f 3 — 2 /f 3 |<4  (2-7)

where,

f 3 — 2 denotes a focal length of the second lens component in the third lens unit, and

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

21. The zoom lens according to claim 16 , wherein the zoom lens satisfies the following conditional expression (2-8)

L T /f T <3.3  (2-8)

where,

L T denotes a total length of the overall zoom lens system at the telephoto end, and

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

22. The zoom lens according to claim 16 , wherein the zoom lens satisfies the following conditional expression (2-9)

3.1 <f T /f W <10  (2-9)

where,

f W denotes the focal length of the overall zoom lens system at the wide angle end, and

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

23. The zoom lens according to claim 16 , wherein the zoom lens satisfies the following conditional expression (2-10)

−5 <f 2 /f W <−1.5  (2-10)

where,

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

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

24. An image pickup apparatus comprising:

a zoom lens; and

an image pickup element which includes an image pickup surface which is disposed on an image side of the zoom lens, and which receives an image formed by the zoom lens, wherein the zoom lens is the zoom lens according to claim 16 .

25. 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; and

a third lens unit having a positive refractive power, wherein

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

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

the zoom lens satisfies the following conditional expressions (3-1), (3-2), and (3-3)

1.3 <|f 3 — 2 /f 3 — 1 |<5  (3-1)

Σ d 3G /f T <0.42  (3-2)

Fno ( W )<2.5  (3-3)

where,

f 3 — 1 denotes a focal length of the first lens component having a positive refractive power in the third lens unit,

f 3 — 2 denotes a focal length of the second lens component having a negative refractive power in the third lens unit,

Σd 3G denotes a total length of the third lens unit,

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

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

26. The zoom lens according to claim 25 , wherein the first lens unit includes a cemented lens.

27. The zoom lens according to claim 25 , wherein the zoom lens satisfies the following conditional expression (3-4)

0.1<(β 2T /β 2W )/(β 3T /β 3W )<0.8  (3-4)

where,

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

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

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

β 3T denotes a lateral magnification at a telephoto end of the third lens unit.

28. The zoom lens according to claim 25 , wherein the zoom lens satisfies the following conditional expression (3-5)

2 <f 3 /f W <5  (2-5)

where,

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

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

29. The zoom lens according to claim 25 , wherein the zoom lens satisfies the following conditional expression (3-6)

0.6 <f 3 — 1 /f 3 <1.2  (3-6)

where,

f 3 — 1 denotes a focal length of the first lens component in the third lens unit, and

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

30. The zoom lens according to claim 25 , wherein the zoom lens satisfies the following conditional expression (3-7)

0.9 <|f 3 — 2 /f 3 |<4  (3-7)

where,

f 3 — 2 denotes a focal length of the second lens component in the third lens unit, and

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

31. The zoom lens according to claim 25 , wherein the zoom lens satisfies the following conditional expression (3-8)

L T /f T <3.3  (3-8)

where,

L T denotes a total length of the overall zoom lens system at the telephoto end, and

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

32. The zoom lens according to claim 25 , wherein the zoom lens satisfies the following conditional expression (3-9)

3.1 <f T /f W <10  (3-9)

where,

f W denotes the focal length of the overall zoom lens system at the wide angle end, and

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

33. The zoom lens according to claim 25 , wherein the zoom lens satisfies the following conditional expression (3-10)

−5 <f 2 /f W <−1.5  (3-10)

where,

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

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

34. An image pickup apparatus comprising:

a zoom lens; and

an image pickup element which includes an image pickup surface which is disposed on an image side of the zoom lens, and which receives an image formed by the zoom lens, wherein

the zoom lens is the zoom lens according to claim 25 .