US Patent 7567389 Zoom lens, image pickup apparatus and digital equipment

A zoom lens includes a first lens group having a negative optical power and including a reflection optical element; a second lens group having a positive optical power; a third lens group having a negative optical power; a fourth lens group having a positive optical power; and, a fifth lens group. At least the second lens group and the fourth lens group move to the object side of the zoom lens for varying a power of the zoom lens from a wide-angle end to a telephoto end. The zoom lens further includes a diaphragm and the diaphragm moves to the object side for varying the power of the zoom lens from the wide-angle end to the telephoto end.