If people know you tinker you get given bits and pieces.
So way back in the 80's I was given an early Pentax (first version after the Ashiflexes) made about 1957 the shutter's disfunctional and there's a ding on the top but I used to leave it out on a self with a lens to be stolen if I was burgled. While the camera needs a lot of work there was a good CZJ 50mm f2.8 Tessar from the late 70's.
I know Steve's seen it before but this was another donated basket case:
Now looks like this:
It took me 18 years to get around to the restoration, so maybe it's time I had a go at the Pentax, meanwhile I'll see what else I can pick up for £1-£2 begining of next month
An aside if you really want to see how a good 35mm camera works get a cheap early screw mount Leica or a Russian copy, they are very easy to work on and you see the logic of how a focal pane shutter works.