Wow, you're an even more commited user than me!! Awesome to see you also have the Tessar, i guess you mean the one for the 1600F, right?
I thought exactly the same as you regarding the f2.8 Tessars, usually they're not too good (although the one in my Contessa, a 50/2.8, is nice). But what about rendering? Better rendering than the Vega-12B? I've been looking at many samples from flickr and I can't reach a conclusion so far.
But there's only one lock pin, and the early bodies, as you can see, have two notches. The second one must be for the aperture actuator on semi-automatic lenses, I'd say. Please check picture:
View attachment 307944
You can see the angle between the two protrusions (aperture actuator and locking pin) is similar to the two notches on the Salyut and Salyut-S camera mount.
Ahh! It was you!! I did find your post days ago and wanted to find them again, so BIG THANKS.
I get really confused here. The automatic lenses have a pin on the back of the lens that has a natural tendency to push out (and close the iris). The camera body keeps the pin in, but at the moment of taking the picture it lets the pin pop out. Thus, the iris closes.
The semi-automatic lenses don't have such pin, please see pic above. Thus, i'm very confused.
Ah, this is great info. The Salyut manual, and the Salyut-S manual, talk about the conditions that must be met for the lens to mount and they mention this. In my experience very very few people bother to read manuals, this would explain everything.
The manuals also don't mention (so far) compatibility issues (or absence of issues) between the older semi-automatic lenses and the new bodies.