Abstract: A standard zoom lens system including a positive first lens group, a negative second lens group, a positive third lens group and a positive fourth lens group. Upon zooming from the short focal length extremity to the long focal length extremity, the positive first lens group, the positive third lens group and the positive fourth lens group move toward the object, and the negative second lens group moves toward the image and thereafter moves toward the object. The positive first lens group includes a negative lens element and a positive lens element. The standard zoom lens system satisfies the following conditions: 7.5<f1/|f2|<9.5??(1) 3.0<f1/f3<5.0??(2) wherein f1 designates the focal length of the positive first lens group; f2 designates the focal length of the negative second lens group; and f3 designates the focal length of the positive third lens group.