An optical control method for use in print finishing, comprising the following steps: First, guiding a planar printed product along a conveying path past at least one optical sensor (14). Secondly, detecting an electronic image (2) by the optical sensor, wherein the electronic image (2) comprises at least one region of the printed product. Third, extracting orientation information of the printed product from the electronic image. Fourth, comparing (51) the orientation information of the printed product from the electronic image with reference orientation information, and generating at least one signal on the basis of a result of the comparison.