Zoom lens optical system
View Patent ↗Provided is a zoom lens optical system suitable for cameras using solid state imaging devices, which is designed compact, has a high zooming ratio and telecentricity, and compensates for color aberration. The zoom lens optical system includes a first lens group having a positive refractive power, for performing zooming, a second lens group having a negative refractive power, for performing zooming, a third lens group having a positive refractive power, for performing zooming, and a fourth lens group having a positive refractive power. The first, second, third, and fourth lens groups are sequentially arranged from an object and satisfy the following equations: f T f W ≥ 8.0 0.2 ≤ L III f W · f T ≤ 0.6 , where f w denotes the overall focal length of the zoom lens optical system at the wide angle position, f T denotes the overall focal length of the zoom lens optical system at the telephoto position, and L III denotes the amount of movement of the third lens group from the wide angle position to the telephoto position. Zooming from the wide angle position to a telephoto position is performed so that the distance between the third lens group and the fourth lens group increases.
1. A zoom lens optical system 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; and
a fourth lens group having a positive refractive power,
wherein the first, second, third, and fourth lens groups are sequentially arranged from an object, and zooming from a wide angle position to a telephoto position is performed so that the distance between the third lens group and the fourth lens group satisfies the equations:
f
T
f
W
>
_
8.0
0.2
<
_
L
III
f
W
·
f
T
<
_
0.6
where f w denotes the overall focal length of the zoom lens optical system at the wide angle position, f T denotes the overall focal length of the zoom lens optical system at the telephoto position, and L III denotes the amount of movement of the third lens group from the wide angle position to the telephoto position.
2. The zoom lens optical system of claim 1 , wherein the zoom lens optical system satisfies the following equation:
2
<
_
D
T
(
III
)
D
W
(
III
)
<
_
6
where D W(III) denotes the distance between the third lens group and the fourth lens group on the optical axis at the wide angle position, and D T(Ill) denotes a distance between the third lens group and the fourth lens group on the optical axis at the telephoto position.
3. The zoom lens optical system of claim 1 , wherein the zoom lens optical system satisfies the following equation:
-
6
≤
D
W
(
II
)
-
D
T
(
II
)
D
W
(
III
)
-
D
T
(
III
)
≤
-
2
where D W(II) denotes the distance between the second lens group and the third lens group on the optical axis at the wide angle position, and D T(II) denotes the distance between the second lens group and the third lens group on the optical axis at the telephoto position.
4. The zoom lens optical system of claim 1 , wherein the fourth lens group moves during zooming to compensate for the movement of the focal position caused during zooming.
5. The zoom lens optical system of claim 1 , wherein the third lens group comprises two tenses having positive refractive powers and a lens having a negative refractive power, which are sequentially arranged from the object.
6. The zoom lens optical system of claim 1 , further comprising a stop between the second lens group and the third lens group, and the stop moves together with the third lens group.
7. The zoom lens optical system of claim 1 , wherein at least one of the third and fourth lens groups comprises at least one aspherical lens.
8. The zoom lens optical system of claim 1 , wherein the distance between the first lens group and the second lens group increases during zooming from the wide angle position to the telephoto position.
9. The zoom lens optical system of claim 1 , wherein the distance between the second lens group and the third lens group decreases during zooming from the wide angle position to the telephoto position.
10. The zoom lens optical system of claim 1 , wherein the zoom lens optical system satisfies the following equations:
0.4
≤
f
II
f
W
·
f
T
≤
0.6
0.8
≤
f
III
f
W
·
f
T
≤
1.2
where f II denotes the focal length of the second lens group, and f III denotes the focal length of the third lens group.
11. A zoom lens optical system 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; and
a fourth lens group having a positive refractive power,
wherein the first, second, third, and fourth lens groups are sequentially arranged from an object, and zooming between the wide angle position to a telephoto position is performed so that the distance between the third lens group and the fourth lens group satisfies the equations:
f
T
f
W
≥
8.0
2
≤
D
T
(
III
)
D
W
(
III
)
≤
6
where f w denotes the overall focal length of the zoom lens optical system at the wide angle position, f T denotes the overall focal length of the zoom lens optical system at the telephoto position, D W(lll) denotes the distance between the third and fourth lens groups on the optical axis at the wide angle position, and D T(III) denotes the distance between the third lens group and the fourth lens group on the optical axis at the telephoto position.
12. The zoom lens optical system of claim 11 , wherein the zoom lens optical system satisfies the following equation:
-
6
≤
D
W
(
II
)
-
D
T
(
II
)
D
W
(
III
)
-
D
T
(
III
)
≤
-
2
where D W(II) denotes the distance, between the second lens group and the third lens group on the optical axis at the wide angle position, and D T(II) denotes the distance between the second lens group and the third lens group on the optical axis at the telephoto position.
13. The zoom lens optical system of claim 11 , wherein the fourth lens group moves during zooming to compensate for the movement of the focal position caused during zooming.
14. The zoom lens optical system of claim 11 , wherein the third lens group comprises two lenses having positive refractive powers and a lens having a negative refractive power, which are sequentially arranged from the object.
15. The zoom lens optical system of claim 11 , further comprising a stop between the second lens group and the third lens group, and the stop moves together with the third lens group.
16. The zoom lens optical system of claim 11 , wherein at least one of the third and fourth lens groups comprises at least one aspherical lens.
17. The zoom lens optical system of claim 11 , wherein the distance between the first lens group and the second lens group increases during zooming from a wide angle position to a telephoto position.
18. The zoom lens optical system of claim 11 , wherein the distance between the second lens group and the third lens group decreases during zooming from the wide angle position to the telephoto position.
19. The zoom lens optical,system of claim 11 , wherein the zoom lens optical system satisfies the following equations:
-
6
≤
D
W
(
II
)
-
D
T
(
II
)
D
W
(
III
)
-
D
T
(
III
)
≤
-
2
where f II denotes a focal length of the second lens group, and f III denotes the focal length of the third lens group.
20. A digital imaging apparatus having a zoom lens system according to claim 1 .
21. A camera having a zoom lens system according to claim 1 .