Hey guys, For what it's worth, Sigma made several lenses in 3rd cam Leica mounts in the 80's. I remember a 35~135, as well as a 24, 135, and I believe a 80~200. I had a 35~135 and although it wasn't up to Leica glass & construction quality, it was a great performer, just as long as you kept the hood on it and didn't include the sun in any compositions. Art Tafil