The invention relates to a projection exposure apparatus for semiconductor lithography, comprising at least one manipulator for reducing image aberrations, wherein the manipulator has at least two optical elements that can be positioned relative to one another, wherein at least one of the optical elements is spatially dependent in terms of its effect on an optical wavefront passing therethrough such that a local phase change of a wavefront propagating in the optical system is produced in the case of a relative movement of the optical elements against one another. Here, the spatially dependent effect of the at least one optical element can be set in a reversible dynamic manner.