The invention relates to a zoom optical system that makes it possible to offer a sensible tradeoff between cost savings and size reductions and an electronic system that incorporates it. The zoom optical system comprises a lens group having negative refracting power and a lens group having positive refracting power. At least one lens is formed by molding of a first lens blank (11) that provides a surface including at least an optical function surface after molding, and a second lens blank (12) that provides a surface other than said surface including at least an optical function surface after molding, wherein the first lens blank (11) and the second lens blank (12) are integrated into a one-piece lens (10).