a positive - negative - positive - positive four group zoom lens system capable of achieving about 30 times variable magnification , the positive - negative - positive - positive four group zoom lens system including , sequentially from an object side to an image side : a first lens group having positive refractive power ; a second lens group having negative refractive power ; a third lens group having positive refractive power ; and a fourth lens group having positive refractive power , wherein the first lens group includes one negative lens , the second lens group includes one positive lens , the third lens group includes a positive lens , the fourth lens group includes at least one positive lens , and a first condition , 0 . 03 & lt ;| f 2 / f t |& lt ; 0 . 08 , is satisfied , wherein f 2 denotes a focal length of the second lens group and f t denotes a focal length of the zoom lens system in a telephoto position .