Adding a pinhole to a camera body cap makes the camera a pinhole camera! Using a medium format camera allows you to use a large piece of film for recording your image. The body cap was used in three ways, yielding three focal lengths. First it was used directly on the body of the camera. Then a macro extension tube was added and the body cap was installed on that. Finally a teleconverter was used with the body cap. Although the size of the pinhole was customized for best results when directly mounting on the camera, the other two configurations yielded usable results. Of course, the same roll of film can be used to shoot "lens" (non-pinhole) images also.