Patent ID: 8248705

Claim:
A zoom lens system, in order from the subject side to the image side thereof, comprising: a first lens of positive refractive power; a second lens of negative refractive power; a third lens of positive refractive power; and a fourth lens of 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: −0.35<L3/Lt<−0.15; where L3 is the movement vector of the third lens group during the zoom lens system moves from the wide-angle state to the telephoto state, the movement vector of the third lens group is a positive value when the third lens group moves from the object 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 object 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: 1.3<(T1+T2+T3+T4)/DIM<1.9, where T1 is the overall length of the first lens group, T2 is the overall length of the second lens group, T3 is the overall length of the third lens group, T4 is the overall length of the fourth lens group, DIM is a diameter of a maximum imaging circle of the zoom lens system.