I have perhaps the same Raptar. I cut a hole in a disc of thin metal and clamped it to the lens with a lens hood. The disc can be mounted on the reverse adaptor with an old UV filter from which the glass has been removed. Another way is to use a Series V adaptor ring the same way on the Raptar. Once one can attach a series adaptor ring to a lens, the lens can fairly easily be mounted on almost anything. Anytime one visits an ancient camera store, ask to see their old filter adaptors. Many treasures are hidden and forgotten is such places.