a zoom lens comprising , in order from an object side thereof , a first lens group of positive refracting power , a second lens group of negative refracting power , an aperture stop , a third lens group of positive refracting power , a fourth lens group of negative refracting power , and a fifth lens group of positive refracting power . upon zooming from the wide - angle end to the telephoto end , at least the first lens group and the aperture stop remain fixed in position , the second and third lens groups move in the optical axis direction , and the separation between each of the lens groups and the aperture stop changes . upon focusing from a focusing - on - infinity state to a close - range - focusing state , the fourth lens group moves in the optical axis direction , with satisfaction of the following : − 0 . 36 & lt ; f 4 / f 1 & lt ;− 0 . 05 , where f1 and f4 are the focal lengths of the first and fourth lens groups , respectively .