Has anyone used them? Has anyone read a review? They have a very nice price and should perform like the best.

I want to get the 50mm but it's $600 USD. I have not read any tests so I won't be buying one until I know what I'm buying. Years ago I had a Contax mount Yashica FR coupled with a Yashica 50mm. Then I bought the Zeiss 50 and the Yashica was sharper. On the other hand, my wife has a Zeiss 45mm Contax mount and it is the sharpest lens out of all the lenses we own; and I've read that the Zeiss 50 M-mount is on par or sharper than the Leica 50mm/F2 'cron.