Abstract: A process and apparatus for exposing light-sensitive printing plates through an original to be copied, which includes forming a cassette-type, vacuum frame assembly by superimposing the printing plate and the original upon one another and disposing them in a cavity formed between an elastic blanket and a light-permeable plate, and evacuating the assembly, to improve contact between the printing plate and the original, at a position removed from a light means, thereafter temporarily placing the assembly in a position to be exposed to the light means and finally removing the assembly from the exposure position. A vacuum frame assembly is provided having a connect-disconnect means for temporary attachment both to the evacuation means removed from the light source and, if desired, to an evacuation means at the exposure position.