Zoom lens and image pickup apparatus having the same
A zoom lens includes a first lens group of positive refractive power; a second lens group of negative power; a third lens group of positive power; a fourth lens group of negative power, and a fifth lens group of positive power arranged from the object side to the image side. At activation of variable power from the wide angle end to the telescopic end, the first, third, fourth and fifth lens groups moves so as to get closer to the object side or the image side at the telescopic end than at the wide angle end; and a gap between the first lens group and the second lens group increases; a gap between the second lens group and the third lens group decreases; a gap between the third lens group and the forth lens group increases; and a gap between the forth lens group and the fifth lens group increases.
1. A zoom lens comprising:
a first lens group of positive refractive power;
a second lens group of negative refractive power;
a third lens group of positive refractive power; and
a fourth lens group of negative refractive power, and
a fifth lens group of positive refractive power arranged in the above-mentioned order from the object side to the image side; wherein,
at activation of variable power from the wide angle end to the telescopic end,
the first lens group moves so as to get closer to the object side at the telescopic end than at the wide angle end;
the third lens group moves so as to get closer to the image side at the telescopic end than at the wide angle end,
the forth lens group moves so as to get closer to the object side at the telescopic end than at the wide angle end; and
the fifth lens group moves so as to get closer to the image side at the telescopic end than at the wide angle end at activation of variable power from the wide angle end to the telescopic end; and
further, at activation of variable power from the wide angle end to the telescopic end,
a gap between the first lens group and the second lens group increases;
a gap between the second lens group and the third lens group decreases;
a gap between the third lens group and the forth lens group increases; and
a gap between the forth lens group and the fifth lens group increases; and
the conditional formulas (1B), (2B) and (3B) below are satisfied:
10 <ft/fw (1B)
0.1<Δ4 Gd/Δ 3 Gd< 0.72 (2B)
−3.0<Δ5 Gd/fw>− 0.16 (3B):
where ft is focal length at the telescopic end:
fw is focal length at the wide angle end:
Δ3Gd is the quantities of displacement of position of the third lens group at the telescopic end with respect to the position of the third lens group at the wide angle end;
Δ4Gd is the quantities of displacement of position of the forth lens group at the telescopic end with respect to the position of the forth lens group at the wide angle end; and
Δ5Gd is the quantities of displacement of position of the fifth lens group at the telescopic end with respect to the position of the fifth lens group at the wide angle end.
2. The zoom lens according to claim 1 , wherein
the conditional formula (4B) below is satisfied:
1.5<Δβ3G<4.0 (4B):
where Δβ3G=β3t/β3w;
β3t is lateral magnification of the third lens group at the wide angle end; and
β3w is lateral magnification of the third lens group at the telescopic end.
3. The zoom lens according to claim 1 , wherein
the conditional formula (5B) below is satisfied:
−1.5 <f 4 /fs<− 0.2 (5B)
where f4 is the focal length of the forth lens group;
fs is defined as is =√(fw×ft): and
fw is the focal length of the zoom lens at the wide angle end.
4. The zoom lens according to claim 1 , wherein
the second lens group moves so as to get closer to the image side at the telescopic end than at the wide angle end.
5. The zoom lens according to claim 1 , wherein
the conditional formula (3A) below is satisfied:
−0.30 <f 4 /ft<− 0.10 (3A):
where f4 is the forementioned focal length of the forth lens group.
6. The zoom lens according to claim 1 , wherein
the forth lens group consists of a negative lens element.
7. The zoom lens according to claim 1 , wherein
the conditional formula (4A) below is satisfied:
0.5 <Dt/ft< 0.95 (4A):
where Dt is the distance from the surface top of the lens surface which is the closest to the object side to the image-formation plane at the telescopic end.
8. The zoom lens according to claim 1 , wherein
the fifth lens group has at least one aspheric surface.
9. The zoom lens according to claim 1 , wherein
the third lens group comprises:
a positive lens element;
a negative lens element; and
a positive lens element arranged in order from the object side.
10. The zoom lens according to claim 1 , wherein
either the forth lens group or the fifth lens group moves in an optical axis when focusing from a distant object toward a near object is done.
11. The zoom lens according to claim 1 , wherein
either all or a part of the lens elements included in the third lens group move in a decentering way with respect to the optical axis.
12. The zoom lens according to claim 1 , wherein
an aperture stop is disposed immediately in front of the third lens group at the object side; and
moves together with the third lens group as one body at activation of variable power.
13. The zoom lens according to claim 1 ,
wherein the first lens group consists of a plurality of positive lens elements and one negative lens element; the second lens group consists of one positive lens element and a plurality of negative lens elements; the third lens group consists of a plurality of positive lens elements and one negative lens element; the forth lens group consists of one lens element; and the fifth lens group consists of one lens element; where each lens element includes a lens body such that only two of the effective surfaces, which are located at the entrance side and the exit side respectively, are in contact with the air.
14. An image pickup apparatus comprising:
a zoom lens in accordance with claim 1 ;
an image pickup device provided with an image pickup surface which converts an optical image into electrical signals.
15. A zoom lens comprising: a first lens group of positive refractive power; a second lens group of negative refractive power; a third lens group of positive refractive power; and a fourth lens group of negative refractive power, and a fifth lens group of positive refractive power arranged in the above-mentioned order from the object side to the image side; wherein, at activation of variable power from the wide angle end to the telescopic end, the first lens group moves; the second lens group moves; the third lens group moves; and the forth lens group moves at activation of variable power from the wide angle end to the telescopic end; further, at activation of variable power from the wide angle end to the telescopic end, a gap between the first lens group and the second lens group increases; a gap between the second lens group and the third lens group decreases; a gap between the third lens group and the forth lens group increases; and a gap between the forth lens group and the fifth lens group increases; and the conditional formulas (1A) and (2A): 0.05& lt; f1/ft< 0.54 (1A):−0.12& lt; f2/ft< −0.01(2A): where f1 is the forementioned focal length of the first lens group: f2 is the forementioned focal length of the second lens group: and ft is focal length at the telescopic end.
16. The zoom lens according to claim 15 , wherein
the conditional formula (4B) below is satisfied:
1.5<Δβ3G<4.0 (4B):
where Δβ3G=β3t/β3w;
β3t is lateral magnification of the third lens group at the wide angle end; and
β3w is lateral magnification of the third lens group at the telescopic end.
17. The zoom lens according to claim 15 , wherein
the forth lens group consists of a negative lens element.
18. The zoom lens according to claim 15 , wherein
the conditional formula (4A) below is satisfied:
0.5 <Dt/ft< 0.95 (4A):
where Dt is the distance from the surface top of the lens surface which is the closest to the object side to the image-formation plane at the telescopic end.
19. The zoom lens according to claim 15 , wherein
the fifth lens group gets closer to the image side at the telescopic end than at the wide angle end at activation of variable power from the wide angle end to the telescopic end.
20. The zoom lens according to claim 15 , wherein
the fifth lens group has at least one aspheric surface.
21. The zoom lens according to claim 15 , wherein
the third lens group comprises:
a positive lens element;
a negative lens element; and
a positive lens element arranged in order from the object side.
22. The zoom lens according to claim 15 , wherein
the conditional formula (2B) below is satisfied:
0.1<Δ4 Gd/Δ 3 Gd< 0.72 (2B)
where fw is focal length at the wide angle end.
23. The zoom lens according to claim 15 , wherein
the third lens group gets closer to the object side at the telescopic end than at the wide angle end,
the forth lens group gets closer to the object side at the telescopic end than at the wide angle end; and
the fifth lens group moves gets closer to the image side at the telescopic end than at the wide angle end at activation of variable power.
24. The zoom lens according to claim 15 , wherein
the conditional formula (4B) below is satisfied:
1.5<Δβ3G<4.0 (4B):
where Δβ3G=β3t/β3w;
β3t is lateral magnification of the third lens group at the wide angle end; and
β3w is lateral magnification of the third lens group at the telescopic end.
25. The zoom lens according to claim 15 , wherein
the conditional formula (5B) below is satisfied:
−1.5 <f 4 /fs<− 0.2 (5B)
where f4 is the focal length of the forth lens group;
fs is defined as is=√(fw×ft): and
fw is the focal length of the zoom lens at the wide angle end.
26. The zoom lens according to claim 15 , wherein
either the forth lens group or the fifth lens group moves in an optical axis when focusing from a distant object toward a near object is done.
27. The zoom lens according to claim 15 , wherein
either all or a part of the lens elements included in the third lens group move in a decentering way with respect to the optical axis.
28. The zoom lens according to claim 15 , wherein
an aperture stop is disposed immediately in front of the third lens group at the object side; and
moves together with the third lens group as one body at activation of variable power.
29. The zoom lens according to claim 15 , wherein
the fifth lens group gets closer to the image side at the telescopic end than at the wide angle end;
the third lens group gets closer to the object side at the telescopic end than at the wide angle end; and
the forth lens group gets closer to the object side at the telescopic end than at the wide angle end; and
the fifth lens group gets closer to the object side at the telescopic end than at the wide angle end at activation of variable power from the wide angle end to the telescopic end.
30. The zoom lens according to claim 15 ,
wherein the first lens group consists of a plurality of positive lens elements and one negative lens element; the second lens group consists of one positive lens element and a plurality of negative lens elements; the third lens group consists of a plurality of positive lens elements and one negative lens element; the forth lens group consists of one lens element; and the fifth lens group consists of one lens element; where, each lens element includes a lens body such that only two of the effective surfaces, which are located at the entrance side and the exit side respectively, are in contact with the air.
31. An image pickup apparatus comprising:
a zoom lens in accordance with claim 15 ;
an image pickup device provided with an image pickup surface which converts an optical image into electrical signals.
32. A zoom lens comprising:
a first lens group of positive refractive power;
a second lens group of negative refractive power;
a third lens group of positive refractive power; and
a fourth lens group of negative refractive power, and
a fifth lens group of positive refractive power arranged in the above-mentioned order from the object side to the image side; wherein,
the first lens group comprises one negative lens element; and
one positive lens element; and
a gap between the first lens group and the second lens group increases;
a gap between the second lens group and the third lens group decreases;
a gap between the third lens group and the forth lens group increases; and
a gap between the forth lens group and the fifth lens group increases; and
the conditional formulas (1C), (2C) and (3C) given below are satisfied:
Vd1n<40 (1C)
80<Vd1p (2C)
θ gF 1 n+ 0.00162 Vd 1 n− 0.6415<0 (3C):
where Vd1n is Abbe number at d line of the above-mentioned at least one negative lens in the foresaid first lens group:
Vd1p is Abbe number at d line of the above-mentioned at least one positive lens in the foresaid first lens group:
θgF1n is partial dispersion ratio between g line and F line:
θgF1n is expressed by θgF1n=(ng1n−nF1n)/(nF1n−nC1n);
nF1n is refractive index at g line of the one negative lens; and
nC1n is refractive indexes at C line of the one negative lens.
33. The zoom lens according to claim 32 , wherein
the conditional formula (4C) below is satisfied:
1.80<Nd1n (4C):
where Nd1n is refractive index of the foresaid at least one negative lens in the first lens group at d line.
34. The zoom lens according to claim 32 , wherein
the fifth lens group is movable when focusing from a distant object toward a near object is done; and
the conditional formula (5C) below is satisfied:
70<Vd5p (5C):
where Vd5p is Abbe number at d line of the foresaid positive lens in the fifth lens group.
35. The zoom lens according to claim 32 , wherein
wherein the conditional formula (1A) below is satisfied: 0.05<f1/ft<0.54(1A): where f1 is the forementioned focal length of the first lens group; and ft is focal length at the telescopic end.
36. The zoom lens according to claim 32 ,
wherein the conditional formula (2A) below is satisfied: 0.05< f1/ft< 0.54 (1A): where f1 is the forementioned focal length of the first lens group, where f2 is the forementioned focal length of the second lens group: and ft is focal length at the telescopic end.
37. The zoom lens according to claim 32 , wherein
the forth lens group gets closer to the object side at the telescopic end than at the wide angle end; and
the conditional formula (3A) below is satisfied:
−0.30 <f 4 /ft<− 0.10 (3A):
where f4 is the forementioned focal length of the forth lens group.
38. The zoom lens according to claim 32 , wherein
the forth lens group consists of one negative lens.
39. The zoom lens according to claim 32 , wherein
the conditional formula (4A) below is satisfied:
0.5 <Dt/ft< 0.95 (4A):
where Dt is the distance from the surface top of the lens surface which is the closest to the object side to the image-formation plane at the telescopic end.
40. The zoom lens according to claim 32 , wherein
the third lens group gets closer to the object side at the telescopic end than at the wide angle end;
the forth lens group gets closer to the object side at the telescopic end than at the wide angle end; and
the fifth lens group gets closer to the image side at the telescopic end than at the wide angle end at activation of variable power from the wide angle end to the telescopic end.
41. The zoom lens according to claim 32 , wherein
the fifth lens group has at least one aspheric surface.
42. The zoom lens according to claim 32 , wherein
the third lens group comprises:
a positive lens element;
a negative lens element; and
a positive lens element arranged in order from the object side.
43. The zoom lens according to claim 32 , wherein
the conditional formula (1B) below is satisfied:
10 <ft/fw (1B)
where fw is focal length at the wide angle end.
44. The zoom lens according to claim 32 , wherein
the third lens group gets closer to the object side at the telescopic end than at the wide angle end;
the forth lens group gets closer to the object side at the telescopic end than at the wide angle end; and
the fifth lens group gets closer to the object side at the telescopic end than at the wide angle end;
and
the conditional formulas (2B) and (3B) below is satisfied: ed:
0.1<Δ4 Gd/Δ 3 Gd< 0.72 (2B)
−3.0<Δ5 Gd/fw<− 0.16 (3B):
where ft is focal length at the telescopic end:
fw is focal length at the wide angle end:
Δ3Gd is the quantities of displacement of position of the third lens group at the telescopic end with respect to the position of the third lens group at the wide angle end;
Δ4Gd is the quantities of displacement of position of the forth lens group at the telescopic end with respect to the position of the forth lens group at the wide angle end; and
Δ5Gd is the quantities of displacement of position of the fifth lens group at the telescopic end with respect to the position of the fifth lens group at the wide angle end.
45. The zoom lens according to claim 32 , wherein
the conditional formula (4B) below is satisfied:
1.5<Δβ3G<4.0 (4B):
where Δβ3G=β3t/β3w;
β3t is lateral magnification of the third lens group at the wide angle end; and
β3w is lateral magnification of the third lens group at the telescopic end.
46. The zoom lens according to claim 32 , wherein
the conditional formula (5B) below is satisfied:
−1.5 <f 4 /fs<− 0.2 (5B)
where f4 is the focal length of the forth lens group;
fs is defined as is=√(fw×ft): and
fw is the focal length of the zoom lens at the wide angle end.
47. The zoom lens according to claim 32 , wherein
either the forth lens group or the fifth lens group moves in an optical axis when focusing from a distant object toward a near object is done.
48. The zoom lens according to claim 32 , wherein
either all or a part of the lens elements included in the third lens group move in a decentering way with respect to the optical axis.
49. The zoom lens according to claim 32 , wherein
an aperture stop is disposed immediately in front of the third lens group at the object side; and
moves together with the third lens group as one body at activation of variable power.
50. The zoom lens according to claim 32 , wherein
the first lens group gets closer to the object side at the telescopic end than at the wide angle end;
the third lens group gets closer to the object side at the telescopic end than at the wide angle end;
the forth lens group gets closer to the object side at the telescopic end than at the wide angle end; and
the fifth lens group gets closer to the image side at the telescopic end than at the wide angle end at activation of variable power from the wide angle end to the telescopic end.
51. The zoom lens according to claim 32 ,
wherein the first lens group consists of a plurality of positive lens elements and one negative lens element; the second lens group consists of one positive lens element and a plurality of negative lens elements; the third lens group consists of a plurality of positive lens elements and one negative lens element; the forth lens group consists of one lens element; and the fifth lens group consists of one lens element; where each lens element includes a lens body such that only two of the effective surfaces, which are located at the entrance side and the exit side respectively, are in contact with the air.
52. An image pickup apparatus comprising:
a zoom lens in accordance with claim 32 ;
an image pickup device provided with an image pickup surface which converts an optical image into electrical signals.