Zoom lens system

1. A zoom lens 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;

a fourth lens group having a positive refractive power;

a fifth lens group having a positive refractive power; and

a sixth lens group having a positive refractive power,

wherein the first to sixth lens groups are sequentially arranged along an optical axis from an object side to an image plane side, and zooming is performed by moving at least one of the second lens group, the fourth lens group and the fifth lens group along the optical axis,

wherein a distance between a focal point of light having a first wavelength and a focal point of light having a second wavelength is about 50 μm or less at a wide-angle position and a telephoto position,

wherein the first wavelength corresponds to green light, the second wavelength corresponds to near infrared (NIR) light,

wherein the third lens group comprises a positive lens and a negative lens sequentially arranged from the object side, and at least one surface of the negative lens is aspherical, and

wherein an Abbe number of the positive lens of the third lens group is less than an Abbe number of the negative lens of the third lens group.

2. The zoom lens system of claim 1 , wherein the first wavelength is about 546 nm, and the second wavelength is about 850 nm.

3. The zoom lens system of claim 1 , wherein the distance between the focal point of light having the first wavelength and the focal point of light having the second wavelength is about 30 μm or less at the wide-angle position.

4. The zoom lens system of claim 1 , wherein the zoom lens system satisfies a following condition:

15

<

f

t

f

w

<

30

,

where f w is a focal length at the wide-angle position, and f t is a focal length at the telephoto position.

5. The zoom lens system of claim 4 , wherein the zoom lens system satisfies a following condition:

TL

f

t

/

f

w

<

8

,

where TL is a distance between an image plane to an object-side surface of one of lenses of the first lens group that is closest to the object side.

6. The zoom lens system of claim 1 , further comprising an aperture stop between the third lens group and the fourth lens group.

7. The zoom lens system of claim 1 , wherein the first lens group, the third lens group, and the sixth lens group are fixed during zooming.

8. The zoom lens system of claim 1 , wherein the zoom lens system satisfies a following condition:

2.5

<

f

1

f

4

<

3.0

,

where f 1 is a focal length of the first lens group, and f 4 is a focal length of the fourth lens group.

9. The zoom lens system of claim 1 , wherein the first lens group comprises a doublet lens at a position closest to the object side, the doublet lens comprising a negative lens and a positive lens sequentially arranged from the object side, and

wherein the zoom lens system satisfies a following condition:

1.5< Vd 12 /Vd 1 <2.5,

where Vd 11 is an Abbe number of the negative lens of the doublet lens, and Vd 12 is an Abbe number of the positive lens of the doublet lens.

10. The zoom lens system of claim 1 , wherein the zoom lens system satisfies a following condition:

30< Vd 32<38

where Vd32 is an Abbe number of the negative lens of the third lens group.

11. The zoom lens system of claim 1 , wherein each of the second lens group, the third lens group, the fourth lens group comprises at least one lens having an aspherical surface.

12. The zoom lens system of claim 1 , wherein the zoom lens system comprises at least five lenses each having a refractive index of about 2.0 or greater.

13. The zoom lens system of claim 1 , wherein the sixth lens group comprises a triplet lens comprising three lenses cemented together.

14. The zoom lens system of claim 1 , wherein the first lens group comprises at least four lenses each having an Abbe number of about 95 or greater.

15. A zoom lens 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;

a fourth lens group having a positive refractive power;

a fifth lens group having a positive refractive power; and

a sixth lens group having a positive refractive power,

wherein the first to sixth lens groups are sequentially arranged along an optical axis from an object side to an image plane side, and zooming is performed by moving at least one of the second lens group, the fourth lens group and the fifth lens group along the optical axis, and

wherein a distance measured in a direction parallel to the optical axis between a focal point of light having a wavelength of about 546 nm and a focal point of light having a wavelength of about 850 nm is about 30 μm or less,

wherein the zoom lens system satisfies a following condition:

15

<

f

t

f

w

<

30

,

where f w is a focal length at a wide-angle position, and f t is a focal length at a telephoto position,

wherein the first lens group comprises at least four lenses each having an Abbe number of about 95 or greater,

wherein the third lens group comprises a positive lens and a negative lens sequentially arranged from the object side, and at least one surface of the negative lens is aspherical, and

wherein an Abbe number of the positive lens of the third lens group is less than an Abbe number of the negative lens of the third lens group.

16. The zoom lens system of claim 15 , wherein the zoom lens system satisfies a following condition:

30< Vd 32<38,

where Vd32 is an Abbe number of the negative lens of the third lens group.