The invention makes a suitable selection from zoom modes and lens elements so thin that the thickness of each lens group can reduced, thereby slimming down a zoom lens with great thoroughness and, hence, an electronic image pickup system. The electronic image pickup system a zoom lens and an electronic image pickup device located on the image plane side of the zoom lens. The zoom lens comprises, in order from the object side, a first lens group G1 comprising two lens components and having generally negative power and a second lens group G2 comprising two lens components and having generally positive power. The focal length of the zoom lens can be varied by varying the air separation between the first lens group G1 and the second lens group G2. The zoom lens should satisfy at least one of conditions (a) to (n).