In graphic arts photography, the percent enlargement or reduction at which the original art or copy is to be photographed. On most process cameras, enlargement and reduction is effected by moving the copyboard and the lens certain predetermined distances from each other, depending upon the amount of the size change desired. Changing the size of the reproduction also necessitates the re-setting of the lens's f/number, as well as the exposure time. These changes can be handled with differing degrees of automation, depending on the camera. See Photography: Graphic Arts Photography.