(1) A sheet of glass, plastic, or metal made to show, according to the data provided by calibration of a camera, the relationship of the principal point to the fiducial marks. A calibration templet is used to rapidly and accurately mark principal points on a sequence of photo-graphs. (2) A sheet of glass, plastic, or metal made to show, according to the data obtained by calibration of a multiple lens camera, the relationships of the principal points to the fiducial markers and used to assemble the photographs from the individual photographs into one composite photograph.