PURPOSE: To set quickly magnification by providing a slit plate and a photosensitive plate on a slide mechanism which is capable of reciprocating movement in a necessary direction orthogonal to an optical axis of video light, respectively.

CONSTITUTION: For instance, when a slit plate 3 is moved at a speed V1 and made to cross all video light beams, in a state that a photosensitive plate 4 is fixed in a projecting range of all differential light beams, a positive negative of the same size graphic (A=A', B=B') as a graphic negative is obtained on the photosensitve plate 4. Subsequently, when a speed ratio of the moving speed V1 of the slit plate 3 and a moving speed V2 of the photosensitive plate 4 is set to 1:1 and they are moved in each opposite direction, a positive negative of a flat type (A'=A, B'=2B), which has magnified a graphic of the graphic negative 2 to two times in only the moving direction is obtained on the photosensitive plate 4. Subsequently, when a speed ratio of the moving speed V1 of the slit plate 3 and a moving speed V3 of the photosensitive plate 4 is set to 1:0.5 and they are mutually moved in the same direction, a positive negative of a long body type (A'=A, B'=1/2B), which has reduced the graphic of the graphic negative 2 to 1/2 time in only the moving direction is obtained on the photosensitive plate 4.