I think those were Leica rangefinders, but I could be wrong. The Olympus I had was quieter than my Nikon, but it wasn't that quiet.
But I really loved to design too, and like I said earlier, they were substantially smaller than other SLRs of the time.
Mark
I knew a professional photographer who worked for the Southern Baptist Convention. He used Leica rangefinders because he often worked during services and did not want to disturb them.
The OM-1, OM-2 3 and 4 were in fact very quiet. The designer whose name I can’t recall, (it was something like Maitaini) put shock absorbers in the mirror mechanism which did make that mirror flap much smoother and quieter. Probably still louder than the Leica.
That pro photographer also used Hasselblads. I still have a lot of pics his assistant made of my wife and Daughter when she was a baby, and of course some had me in them.
The Pro actually wanted to use my wife as a model, she was that photogenic, but we lived to far away. He did take some of her while we were visiting the retreat.