There's nothing wrong with Minolta lenses, that's for sure. But the lenses made by Minolta for Leitz were made to Leica specs. In addition to the 16mm they made an 80-200 Elmar zoom. I used to have the zoom and it was excellent. I'm not aware of any M lenses made in Japan. What's interesting is the lenses Leica makes for the Japanese market. For example, there is a big contingent of S-mount fans in Japan. For them Leitz has built Summicron and Summilux ASPH lenses. So you can put a very modern lens on your Luftwaffe IIIc Kalt.