External viewfinders for 21mm lens on Leica M
I'm about to have someone purchase the Zeiss C Biogon 4.5/21mm lens for my Leica. However, I'm not so sure which viewfinder to get. There are two options: the Zeiss with 21mm framelines, and the Leica with 21/24/28 framelines. The Leica is only slightly more expensive and is made of metal, whereas the Zeiss looks plastic. It looks like the Leica is a no-brainer. What do you think? Any first hand experiences? I can only check them on the internet, that's why I needed to ask.
A quick reply would be appreciated as my wife is in London right now and waiting for instructions :)