Patent ID: 8248706

Claim:
A zoom lens system, in order from the subject side to the image side thereof, comprising: a first lens group with positive refractive power; a second lens group with negative refractive power; a third lens group with positive refractive power; and a fourth lens group with positive refractive power; wherein the first, second, third and fourth lens groups are capable of moving along the optical axis of the zoom lens system; wherein the zoom lens system satisfies the following formula: 0.15<|L 3 |/Lt<0.25, where L 3 is a movement vector of the third lens group during the zoom lens system moves from a wide-angle state to a telephoto state, the movement vector of the third lens group is a positive value when the third lens group moves from the subject side to the image side, the movement vector of the third lens group is a negative value when the third lens group moves from the image side to the subject side, Lt is the total length of the zoom lens system along the optical axis in the telephoto state; wherein the zoom lens system satisfies the following formula: 0.15<f 3 /ft<0.2, wherein f 3 is the effective focal length of the third lens group, ft is the effective focal length of the zoom lens system in the telephoto state.