I have a Mockba-4 also. Although it was pretty beat up on the outside, had been repainted, and the linkage was a bit sloppy, the lens was clean, aligned and the RF works well. The industar lens is very sharp and contrasty, and gives very nice negs, even handheld at fast shutter speeds. For about $40, a pretty good deal for a 6x9 rangefinder. The lens quality seems about on par with the color-skopar on my Bessa-1, which I consider a fine lens.

cheers

Tim