The 50mm lens will be about 20 dioptre, so it's effectively a pretty extreme close-up lens. A SLR wide-angle would give an even bigger image, but the retrofocal design ( to keep the rear element clear of the mirror) would help give some working room. There were reversing rings made, which let you mount a lens back to front, which was supposed to give a better macro image -- the lens optical design would expect the film to be closer than the object. I don't recall ever hearing of an adaptor to do what you did. It might be possible to do something with a pair of Cokin adaptors, for something a bit more solid.