A photographic copier has a first platform for supporting an original to be copied, and a second platform for supporting copy paper. A focusing system is disposed between the platforms and includes a plate which can be mounted at different distances from the platforms. The plate has a central opening which removably receives a tubular holder. The holder is supported in the opening by a ring which permits the position of the holder relative to the plate to be adjusted. Two lenses are removably mounted in the holder and serve to project an image of the original onto the copy paper. Different magnifications can be achieved in that the copier comes equipped with a variety of holders having different lengths, and a few selected lenses having different optical characteristics. The magnification is changed by simply interchanging holders and/or lenses, and adjusting the position of a holder to be used relative to the plate.