A method includes moving a correction device into a neutral position; subsequently ascertaining, for a given arrangement of imaging light channels in the illumination optical unit of the projection exposure apparatus, intensity distributions of at least some of the individual imaging light partial beams along a transverse coordinate transverse to a displacement direction of an object to be imaged; subsequently ascertaining, in dependence on the transverse coordinate, an actual variation of actual values of structure image sizes of object structures in an image field, onto which the object is imaged; and subsequently specifying a predetermined variation of the structure image sizes over the transverse coordinate and displacing correction elements of the correction device, starting from the neutral position, such that the actual variation matches the predetermined variation within a tolerance bandwidth. The method can provide improved imaging results as compared to known uniformity adjustment.