In the world of 50mm rangefinder lenses there are many choices from modern Leica perfection to old classic RF lenses from the past like the Canon 50 1.8 LTM (which I also own) and everything in between. The 50mm is a classic focal length and probably the most popular for rangefinder shooters. My #1 recommendation for a 50mm Lens is money is no object is the Leica 50 Summilux ASPH or new 50 Summicron APO. If money is an object, and for most of us it is, you can still buy a lens or two that will not hamper you in any way and still give you gorgeous results. Zeiss ZM glass is just one of those options where you get to pay less but still have that special quality that makes you say “wow” when you nail a special shot.