I initially solved the lens question this way:
First a few 50mm's that came with my bodies, old and newer. Like I have 2 RTL 1000 bodies, one of which work, but both delivered 50mm's....
Then I started searching for lenses and quickly settled for the easy solution: I got a range of Soligor T2 / T4 lenses and found Exakta T2 / T4 adapters, just a few adapters will do, but you can buy the whole catalog of lenses.....
That settled, just start taking pictures, and as you eventually find more *original* lenses (what is THAT for an Exakta??), CZ J and Meyer for instance, just shift the Soligors over to other camera bodies via more adapters.
I have adapters for most of my SLR bodies, so choosing a lens sometimes takes a long time!
Many will berate old Soligor lenses, I have found that that is just more drivel than fact. They are even quite reliable as far as QC goes, I have 3 135mm f:3,5 lenses, all spitting image and all deliver quality results, impossible to see any difference.
I'm not saying there ain't better lenses under the sun, but for handheld photography outside of a lab......
Also I find it slightly perverse, putting on a fairy modern zoom lens on a 60 year old camera body and snapping away, I recommed 3.rd party lenses as an adventure and a way to discover more thoroughly how photography WAS, back in the day, for instance getting to know how to manipulate and make pictures in a hurry with pre-set lenses, using a handheld exposure meter, and so on, is an eye-opener for anyone that grew up with autofocus, auto everything cameras and lenses!