The invention relates to a method -for improving the imaging properties of a micro lithography projection objective (50), wherein the projection objective has a plurality of lenses (L1, L2, L3, L4, L5, L6, L7, L8) between an object plane and an image plane, a first lens of the plurality of lenses being assigned a first manipulator (ml, Mn) for actively deforming the lens, the first lens being deformed for at least partially correcting an aberration, at least one second lens of the plurality of lenses furthermore being assigned at least one second manipulator, and the second lens being deformed in addition to the first lens. Furthermore, a method is described for selecting at least one lens of a plurality of lenses of a projection objective as actively deformable element, and a projection objective.