The present invention is directed to a zoom lens which includes, in order from an object side: a first lens group having a negative refractive power; a second lens group having a positive refractive power; and a third lens group having a positive refractive power. While zooming from a wide-angle position to a telephoto position, the distance between the third lens group and an image side is greater at the wide-angle position than at the telephoto position. The zoom lens satisfies the following conditional expression: 1.0 ≤ L II f W f T ≤ 1.5 where f W denotes the total focal length at the wide-angle position; f T denotes the total focal length at the telephoto position; and L II denotes the moving distance of the second lens group from the wide-angle position to the telephoto position.
1. A zoom lens comprising, in order from an object side:
a first lens group having a negative refractive power, comprising a first lens having a negative refractive power and a second lens having a positive refractive power, wherein the first lens includes a convex meniscus surface facing the object side;
a second lens group having a positive refractive power, comprising a third lens having a positive refractive power and a fourth lens having a negative refractive power; and
a third lens group having a positive refractive power, comprising at least one fifth lens having a positive refractive power;
wherein a distance between the third lens group and an image side is greater at a wide-angle position than at a telephoto position, and
wherein the zoom lens satisfies the expressions,
1.0
≤
L
II
f
W
f
T
≤
1.5
,
and
1.2
≤
f
I
f
W
f
T
≤
1.5
,
and
1.2
≤
f
I
f
W
f
T
≤
1.5
,
wherein f W denotes the total focal length at the wide-angle position; f T denotes the total focal length at the telephoto position; L II denotes the moving distance of the second lens group from the wide-angle position to the telephoto position; and f I denotes the focal length of the first lens group.
2. The zoom lens as claimed in claim 1 , wherein the zoom lens further satisfies the expression,
1.0
≤
f
II
f
W
f
T
≤
1.3
,
wherein f II denotes the focal length of the second lens group.
3. The zoom lens as claimed in claim 1 , wherein the zoom lens further satisfies the expression,
1.5
≤
f
III
f
W
f
T
≤
2.0
,
wherein f III denotes the focal length of the third lens group.
4. The zoom lens as claimed in claim 1 , wherein the first lens of the first lens group has at least one aspheric surface.
5. The zoom lens as claimed in claim 4 , wherein the third lens of the second lens group has at least one aspheric surface.
6. The zoom lens as claimed in claim 1 , wherein the third lens of the second lens group has at least one aspheric surface.
7. The zoom lens as claimed in claim 1 , wherein the zoom lens further satisfies the expression,
| n In −n Ip |≦0.15,
wherein n In denotes the refractive index of the lens having a negative refractive power in the first lens group at d-line, and n Ip denotes the refractive index of the lens having a positive refractive power in the first lens group at d-line.
8. The zoom lens as claimed in claim 1 , wherein the third lens group consists of one lens.
9. A zoom lens comprising, in order from an object side:
a first lens group having a negative refractive power, comprising a first lens having a negative refractive power and a second lens having a positive refractive power, wherein the first lens includes a convex meniscus surface facing the object side;
a second lens group having a positive refractive power, comprising a third lens having a positive refractive power and a fourth lens having a negative refractive power; and
a third lens group having a positive refractive power, comprising at least one fifth lens having a positive refractive power,
wherein a distance between the third lens group and an image side is greater at a wide-angle position than at a telephoto position;
wherein the zoom lens satisfies the expressions,
0.5
≤
f
IP
f
I
≤
1.1
,
and
1.5
≤
f
III
f
W
f
T
≤
2.0
,
wherein f I denotes the focal length of the first lens group; f IP denotes the focal length of the lens having a positive refractive power in the first lens group; f III denotes the focal length of the third lens group: f W denotes the total focal length at the wide-angle position; and f T denotes the total focal length at the telephoto position.
10. The zoom lens as claimed in claim 9 , wherein the zoom lens further satisfies the expression
1.2
≤
f
I
f
W
f
T
≤
1.5
.
11. The zoom lens as claimed in claim 9 , wherein the first lens of the first lens group has at least one aspheric surface.
12. The zoom lens as claimed in claim 11 , wherein the third lens of the second lens group has at least one aspheric surface.
13. The zoom lens as claimed in claim 9 , wherein the third lens of the second lens group has at least one aspheric surface.
14. The zoom lens as claimed in claim 9 , wherein the zoom lens further satisfies the expression,
| n In −n Ip |≦0.15,
wherein n In denotes the refractive index of the lens having a negative refractive power in the first lens group at d-line; and n IP denotes the refractive index of the lens having a positive refractive power in the first lens group at d-line.
15. The zoom lens as claimed in claim 9 , wherein the third lens group consists of one lens.
16. The zoom lens as claimed in claim 9 , wherein the zoom lens further satisfies the expression,
1.0
≤
L
II
f
W
f
T
≤
1.5
,
wherein L II denotes the moving distance of the second lens group from the wide-angle position to the telephoto position.
17. The zoom lens as claimed in claim 9 , wherein the zoom lens further satisfies the expression,
1.0
≤
f
II
f
W
f
T
≤
1.3
,
wherein f II denotes the focal length of the second lens group.