Patent ID: 7944619

Claim:
A zoom optical system comprising, in order from an object side: a first group having negative refracting power; a second group having positive refracting power; a third group having negative refracting power; and a fourth group having positive refracting power; wherein the first group comprises a prism component arranged on an utmost object side and comprising an entrance surface having a concave surface directed toward the object side, a reflecting surface and an exit surface; and wherein the second group comprises an aperture stop; wherein, when zooming is carried out from a wide angle end to a telephoto end, the second group and the third group are moved toward the object side respectively, an interval between the first group and the second group decreases, and an interval between the second group and the third group and an interval between the third group and the fourth group increase respectively; and wherein the following conditions (1) and (2) are satisfied: 1.4 <G 23 W/G 34 W< 3 (1) 0.4 <G 23 T/G 34 T< 1.5 (2) where G 23 W is an interval between the second group and the third group at the wide angle end, G 34 W is an interval between the third group and the fourth group at the wide angle end, G 23 T is an interval between the second group and the third group at the telephoto end, and G 34 T is an interval between the third group and the fourth group at the telephoto end.