a zoom lens is disclosed that is formed of only two lens groups . the first lens group includes , from the object side , a plastic lens element having negative refractive power and an aspheric surface , and a lens element having positive refractive power . the second lens group includes , from the object side : a biconvex lens element having an aspheric surface ; a lens element having negative refractive power , a smaller curvature on its object side , and with its image - side surface joined to a biconvex lens element . the zoom lens satisfies specified conditions to : allow for ease of manufacture and assembly while maintaining favorable correction of various aberrations , assure that the zoom lens is compact in both the operational and retracted positions , assure that the zoom lens is not easily damaged , and assure that the optical performance is well - maintained despite changes in ambient conditions , such as temperature .