OSHPF Opensource High Precision Focusing Ring for M65 17-31

for use with M65 17-31mm focusing tube, see https://www.printables.com/model/1400453-linhof-617s-iii-lens-super-angulon-72mm-xl as an example

I generate common schneider lenses, since their EFL are easy to find. I also provide a hpf generator so you can create for your own hpf ring/lenses

find the distance label generator on my github:

https://github.com/RayforLoy/OSHPF-Label-generator/tree/main