I bought a Carl Zeiss Jena Triotar 135 f/4 with stiff focus-ring. I disassembled the lens to fix the focus ring, work done.
But now I would like to disassemble the lenses as well, because the internal lens is dirty and I want to clean it.
In front of the objective I can't see any screws or notch to unscrew the lenses. In rear there are three notches, for three different screwed-rings.
Which one must I unscrew to disassemble the lens?