p.1 #2 · Minolta Leitz CL with the new Thypoch 28mm f2.8
Now that is a handsome and compact 28mm M combo!
Can't help with the filter, other than maybe suggest to consider a step-up ring to a more common filter size. That's what I do with TTA 28mm f/5.6, using 39mm filter with the 34mm - 39mm adapter.