I think the zorki 5 and 6 are the better one's. I placed a leica summarit 5cm on my zorki 6. I had some bad luck with some F.S.U lenes. The summarit has very shallow depth of field so the wide rangefinder base worked well for me. One of my other favorite russian camera's would be the mockba 5 or moscow 5 a copy of a 6x9cm ziess ikonta I've had both and can't tell the difference between the photo's taken with these 2 camera's