Shoten has released two M-mount rangefinder adapters. The M42-LM R50 and PK-LM R50 helicoid mount adapters transform 50mm prime lenses for M42 and K mount cameras into rangefinder-coupled lenses for M-mount cameras.

According to Shoten, this adjustment guide can be used to fine-tune the distance meter. The adapter comes with a precision screwdriver for adjusting the distance meter. The adapter is only compatible with 50mm lenses, and when focusing in live view, the helicoid can be used to shorten the minimum focus distance.

Toro Sawamura’s Japanese article provides a hands-on report on the latest Shoten adapters. Sawamura covers the adjustment procedure and user experience with various low-cost DSLR lenses converted for use on an M-mount rangefinder camera. Fast lenses, like 50mm f/1.4 primes, are simple to focus and provide sharp images. Sawamura even put a prototype NF-LM R50 coupler through its paces, allowing him to utilize F-mount lenses on M-mount cameras. This adapter should be available soon, but no specific availability information is supplied. According to Sawamura, Shoten is also working on adapters for Yashica/Contax and Exakta lenses.

While the new Shoten R50-series adapters lack an autofocus motor, they appear poised to extend lens options for Leica M-mount shooters considerably. While the 50mm focal length limit is rather restrictive, many 50mm lenses are available, particularly on the used market. The ability to change the adapter’s distance meter, allowing for infinity focus, is amazing and helps distinguish these coupler adapters from others on the market, some of which only work at close-up focusing distances. Ensuring an accurate distance meter is difficult, but Sawamura’s hands-on experience implies Shoten succeeded.