Scanner camera with digital signal output and focusing system provided as part of a booklet printing apparatus

A scanner camera (1) can be used to copy printed pages, in particular in books and the like, simply and economically. The camera (1) has a sensor line for scanning, line by line, the image of the original projected by the lens system (5) in the focal plane (4) of the camera. A device for focusing the image of the original in the focal plane (4) comprises a grid structure (6) which is illuminated through the lens system and projected from the focal plane (4) into the object plane, in which the original is located. The image of the original is focused if the image of the grid structure (6) is seen to be focused on the original. The line sensor is displaced hydraulically.