Interesting camera but, as pointed out above, there are a LOT of lenses that don't fit because of that curved ledge above the lens mount. Basically, any lens with a base diameter larger than 1-15/16 inches will not fit. During the time I owned a Leningrad, I was disappointed to discover that NONE of my Voigtlander or Canon LTM lenses (except the skinny Canon 50/1.8) would fit.
Another peculiarity that can cause problems is that the sprocketless film advance design causes the spacing between frames to increase gradually as you move through a roll. At the beginning the frames almost touch each other; by the end of a 36-exposure roll they're much farther apart than standard. This was a compromises that the designers accepted in order to eliminate the need for a sprocket shaft system. It's not an issue if you develop and print your own film, but if you want to use lab processing it will cause havoc with automatic film-cutting and slide-mounting equipment.
Also, changing film is
very slow because the rewind knob works slowly and the back-locking mechanism is difficult to unlock.
My Leningrad photo page is still up;
here's a link.
If you want a former-Soviet LTM camera that has finder frames and is suitable for rapid action, you might want to consider the Droug as an alternative. Its finder shows frames only for 50mm and 85mm lenses, but you did mention that you're looking for a portrait lens, and 85mm works well for that. I've got a page on the Droug, too --
here's a link.
I'm not dissing the Leningrad as a collectible or a "fun" camera -- it's a fascinating and clever design. But if you want to do RF portraiture with minimal headaches, I have to say it wouldn't be my first choice.
