a zoom lens system includes a positive first lens group , a negative second lens group , a positive third lens group , and a positive fourth lens group . upon zooming , the first through fourth lens groups move toward the object so that the distance between the first and the second lens groups becomes longer , the distances among the second , the third and the fourth lens groups become shorter . the third lens group includes a positive 3 - 1 st lens element , a positive 3 - 2 nd lens element , and a negative 3 - 3 rd lens element . the zoom lens system satisfies the following condition : − 1 . 8 & lt ; ør 3 - 3 - 1 / øw & lt ;− 1 . 1 ... wherein ør 3 - 3 - 1 designates the surface power of the object - side surface of the negative 3 - 3 rd lens element of the third lens group ; and øw designates the power of the entire lens system at the short focal length extremity .