The invention relates to a workpiece processing machine (1), and to a method for operation of a workpiece processing machine (1). The workpiece processing machine (1) comprises an automatically adjustable stop finger (17), and has, for monitoring adjustment movements of the stop finger (17), a monitoring device (36, 37, 38) that comprises an illuminating device (36) and at least one optical detection device (37). In operation of the workpiece processing machine (1), during an automatically controlled adjustment movement of the stop finger (17), a light beam (38) is radiated into an area ahead of the stop finger (17) in the adjustment direction. Upon detection of a first light image (43) projected onto an object surface (42) by the first light beam (38), a safety measure is triggered.