The first soviet lens I have been trying out is an Industar-50-2 made by KMZ.
As with many of the older M42 mount lenses, the Industar-50-2 features a smooth (if not loose) aperture ring with no stops, meaning that it rotates smoothly from f/16 up through f/3.5.
You focus the Industar wide open and then stop down to the desired aperture in order to meter. This can be tough to do by touch given the lack of clicks, but on the other hand there is nothing preventing you from dialing in any intermediate aperture to nail exposure just where you want it.
The relatively slow maximum aperture means that this is not a good lens for low-light situations or minimizing the depth of field. However, I have found that I can shoot wide open even in daylight and still get nice, rounded out of focus elements in the photo.