They work , and work well if you take the time to learn how to use them ...
Just a few I was able to find with a CF filter ...
And one with lots and lots of glass
My advice is simple - Just do it !
It will either work for you or not , its that simple .
The lens you want to use M 50mm F2 , is not going to be the best choice . But if its what you have , then do it !
I would recommend a x4 CF filter , and they can be a little hit or miss depending on quality . If your unlucky you may get one that does not work well , on the other hand you may get one that is fantastic ( CF filter ) .
The cheaper you go , the more like a lottery it becomes .
Buy a brand name CF filter , and you should be good . ( But you will pay more = So you have to chose )