In a printing apparatus, individual positional data for positions of four object marks provided on a plurality of FPCs held on a conveyance tray are acquired by a mark position acquisition section based on an image acquired by an image acquisition unit. By use of an appropriate controller for the adjustable optical elements, characteristics of the optics can be advantageously varied. In addition, the present invention is related to a wind energy plant. The reception mode used by the RCC at a given time may be selected automatically, i. The illumination device has a light source and a light guide plate that is disposed next to the light source.