Method for determining an operational parameter for an imaging device for imaging at least one part of a build plane, in particular for a determination device for determining at least one parameter of an energy beam for an apparatus for additively manufacturing three-dimensional objects, comprising the steps: determining at least one spot parameter that relates to an extension of a spot, in particular a spot of an energy beam, in a determination plane; determining a difference between the determined spot parameter and a nominal spot parameter; determining an imaging parameter of the imaging device based on the determined difference adjusting the imaging parameter based on the determined difference.