I've used these before,
Fotodiox Lens Mount Adapter M39 (39MM x1 Thread Leica Screw Mount) Lens to Le... | eBay
inexpensive, fine for 50s.
The Voigtlander adapters are the best- but run ~$60. For wide-angle and telephoto lenses, absolute correct thickness is essential. For a 50mm lens- not as critical.
Fotodiox Lens Mount Adapter M39 (39MM x1 Thread Leica Screw Mount) Lens to Le... | eBay
inexpensive, fine for 50s.
The Voigtlander adapters are the best- but run ~$60. For wide-angle and telephoto lenses, absolute correct thickness is essential. For a 50mm lens- not as critical.