Patent ID: 7974017
Filing Date: 2011-07-05
Classification: G02B

Abstract:
1. A zoom lens comprising, in order from its object side: a first lens unit having a negative refracting power; a second lens unit having a positive refracting power; a third lens unit having a negative refracting power; and a fourth lens unit having a positive refracting power, wherein the zoom lens comprises an aperture stop disposed between the first lens unit and the third lens unit, during zooming from the wide angle end to the telephoto end, distances between the lens units change, the first lens unit moves first toward the image side and thereafter toward the object side, the second lens unit moves in such a way as to be located closer to the object side at the telephoto end than at the wide angle end, a distance between the second lens unit and the third lens unit is larger at the telephoto end than at the wide angle end, and the aperture stop moves in such a way as to be located closer to the object side at the telephoto end than at the wide angle end, and the second lens unit and the third lens unit satisfy the following conditional expressions (1) and (2): where β 2(w) and β 2(t) are lateral magnifications of the second lens unit respectively at the wide angle end and at the telephoto end, and β 3(w) and β 3(t) are lateral magnifications of the third lens unit respectively at the wide angle end and at the telephoto end.