High magnification zoom lens system
View Patent ↗A high magnification zoom lens is provided. The zoom lens includes a first lens group including a single positive lens and having a positive refractive power, a second lens group having a negative refractive power, a third lens group having the positive refractive power, a fourth lens group having the positive refractive power, and a fifth lens group having the positive refractive power. The first through fifth lens groups are sequentially arranged from an object side toward an image side. The first lens group, the second lens group, and the third lens group are moved in a direction of an optical axis to change magnification. The fourth lens group is moved to compensate for a movement of a focal position occurring during the magnification change, and the fifth lens group is fixed. Accordingly, the zoom lens is compact, has high magnification, and satisfies conditions of a long back focal length and telecentricity that are required when a solid image pickup device is used.
1. A zoom lens comprising:
a first lens group comprising a single positive lens and having a positive refractive power;
a second lens group having a negative refractive power;
a third lens group having a positive refractive power and comprises at least one aspherical lens;
a fourth lens group having a positive refractive power; and
a fifth lens group having a positive refractive power;
wherein the first through fifth lens groups are sequentially arranged from an object side toward an image side, and during magnification change, the first lens group, the second lens group, the third lens group, and the fourth lens group are moved and the fifth lens group is fixed.
2. The zoom lens of claim 1 , wherein the fourth lens group compensates for movement of a focal position occurring during the magnification change.
3. The zoom lens of claim 1 , wherein the second lens group satisfies
0.6
≤
f
2
f
W
f
T
≤
1.0
,
where f W is an entire focal length at a wide-angle end, f T is an entire focal length at a telephoto end, and f 2 is a focal length of the second lens group.
4. The zoom lens of claim 1 , wherein the third lens group satisfies
0.8
≤
f
3
f
W
f
T
≤
1.2
,
where f W is an entire focal length at a wide-angle end, f T is an entire focal length at a telephoto end, and f 3 is a focal length of the third lens group.
5. The zoom lens of claim 1 , wherein the fifth lens group satisfies
2
≤
f
5
f
W
f
T
≤
3
,
where f W is an entire focal length at a wide-angle end, f T is an entire focal length at a telephoto end, and f 5 is a focal length of the fifth lens group.
6. The zoom lens of claim 1 , further comprising a diaphragm between the second lens group and the third lens group, wherein the diaphragm is moved together with the third lens group.
7. The zoom lens of claim 1 , wherein a distance between the first lens group and the third lens group is maintained constant.
8. The zoom lens of claim 1 , wherein the fifth lens group comprises a single aspherical lens.
9. The zoom lens of claim 1 , wherein the first lens group consists of a single lens, the fourth lens group consists of a single lens, and the fifth lens group consists of a single lens.
10. A zoom lens comprising:
a first lens group having a positive refractive power;
a second lens group having a negative refractive power;
a third lens group having a positive refractive power;
a fourth lens group having a positive refractive power; and a fifth lens group having a positive refractive power;
wherein the first through fifth lens groups are sequentially arranged from an object side toward an image side; the first lens group, the second lens group, and the third lens group are moved in a direction along an optical axis to change magnification; and the second lens group satisfies
0.6
≤
f
2
f
W
f
T
≤
1.0
,
where f W is an entire focal length at a wide-angle end, f T is an entire focal length at a telephoto end, and f 2 is a focal length of the second lens group.
11. The zoom lens of claim 10 , wherein the fourth lens group is moved to compensate for movement of a focal position occurring during the magnification change, and the fifth lens group is fixed.
12. The zoom lens of claim 10 , wherein the fifth lens group satisfies
2
≤
f
5
f
W
f
T
≤
3
,
where f 5 is a focal length of the fifth lens group.
13. The zoom lens of claim 10 , wherein the first lens group consists of a single positive lens.
14. The zoom lens of claim 10 , wherein the third lens group satisfies
0.8
≤
f
3
f
W
f
T
≤
1.2
,
where f 3 is a focal length of the third lens group.
15. The zoom lens of claim 10 , further comprising a diaphragm between the second lens group and the third lens group, wherein the diaphragm is moved together with the third lens group.
16. The zoom lens of claim 10 , wherein a distance between the first lens group and the third lens group is maintained constant.
17. The zoom lens of claim 10 , wherein the second lens group comprises a first lens having a positive refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power, which are sequentially arranged from the object side.
18. The zoom lens of claim 10 , wherein the third lens group comprises a first lens having a positive refractive power, a second lens having a positive refractive power, and a third lens having a negative refractive power, which are sequentially arranged from the object side.
19. The zoom lens of claim 10 , wherein the fourth lens group consists of a single lens.
20. The zoom lens of claim 10 , wherein the fifth lens group consists of a single lens.
21. The zoom lens of claim 10 , wherein the fifth lens group comprises a single aspherical lens.
22. The zoom lens of claim 10 , wherein the third lens group comprises at least one aspherical lens.
23. The zoom lens of claim 10 , wherein during the magnification change, the first and third lens groups are linearly moved and the second lens group is moved forming a curve.
24. A zoom lens comprising:
a first lens group having a positive refractive power;
a second lens group having a negative refractive power;
a third lens group having a positive refractive power;
a fourth lens group having a positive refractive power; and
a fifth lens group having a positive refractive power;
wherein the first through fifth lens groups are sequentially arranged from an object side toward an image side; and to change magnification, the first and third lens groups are linearly moved such that a distance between the first and third lens groups is maintained constant and the second lens group is moved.
25. The zoom lens of claim 24 , wherein the zoom lens satisfies
0.6
≤
f
2
f
W
f
T
≤
1.0
,
where f W is an entire focal length at a wide-angle end, f T is an entire focal length at a telephoto end, and f 2 is a focal length of the second lens group.
26. The zoom lens of claim 24 , wherein the third lens group satisfies
0.8
≤
f
3
f
W
f
T
≤
1.2
,
where f W is an entire focal length at a wide-angle end, f T is an entire focal length at a telephoto end, and f 3 is a focal length of the third lens group.
27. The zoom lens of claim 24 , wherein the fifth lens group satisfies
2
≤
f
5
f
W
f
T
≤
3
,
where f W is an entire focal length at a wide-angle end, f T is an entire focal length at a telephoto end, and f 5 is a focal length of the fifth lens group.
28. The zoom lens of claim 24 , wherein the first lens group consists of a single positive lens.
29. A zoom lens comprising:
a first lens group consisting of a single positive lens and having a positive refractive power;
a second lens group having a negative refractive power;
a third lens group having a positive refractive power;
a fourth lens group having a positive refractive power; and
a fifth lens group having a positive refractive power;
wherein the first through fifth lens groups are sequentially arranged from an object side toward an image side, and during magnification change, the first lens group, the second lens group, the third lens group, and the fourth lens group are moved and the fifth lens group is fixed.
30. The zoom lens of claim 29 , wherein the fourth lens group compensates for movement of a focal position occurring during the magnification change.
31. The zoom lens of claim 29 , wherein the second lens group satisfies
0.6
≤
f
2
f
W
f
T
≤
1.0
,
where f W is an entire focal length at a wide-angle end, f T is an entire focal length at a telephoto end, and f 2 is a focal length of the second lens group.
32. The zoom lens of claim 29 , wherein the third lens group satisfies
0.8
≤
f
3
f
W
f
T
≤
1.2
,
where f W is an entire focal length at a wide-angle end, f T is an entire focal length at a telephoto end, and f 3 is a focal length of the third lens group.
33. The zoom lens of claim 29 , wherein the fifth lens group satisfies
2
≤
f
5
f
W
f
T
≤
3
,
where f W is an entire focal length at a wide-angle end, f T is an entire focal length at a telephoto end, and f 5 is a focal length of the fifth lens group.
34. The zoom lens of claim 29 , further comprising a diaphragm between the second lens group and the third lens group, wherein the diaphragm is moved together with the third lens group.
35. The zoom lens of claim 29 , wherein a distance between the first lens group and the third lens group is maintained constant.
36. The zoom lens of claim 29 , wherein the fifth lens group comprises a single aspherical lens.
37. The zoom lens of claim 29 , wherein the third lens group comprises at least one aspherical lens.
38. The zoom lens of claim 29 , wherein the fourth lens group consists of a single lens, and the fifth lens group consists of a single lens.