Intent was: readjust the end of focus ring travel on a new FD 28mm f2.8 so it goes a few mm over infinity, as makes senses for use with various adapters.
Plan of action was: Find the adjustable stop tab as you would find in an original FD lens.
What happened was: Accidentally disengaged helicoid searching around in the lens. Rethreaded helicoids with the outer helicoid screwed down reasonably far.
Result: Accidentally as wanted, albeit a bit drastic (focus scale off by 2cm travel, over-infinity possible, acceptable)
Is there an official/correct way to adjust the infinity stop to be at over-infinity, without directly modifying helicoid alignment?
Is the workshop/factory way to adjust that actually in how much you pre-loosen the outer helicoid?
I am not talking about just calibrating the scale, which is (normally) a matter of just repositioning the focus ring after loosening three screws (which indeed moves a part that keeps you from actually disengaging the helicoid, however the counterpart is on the outer helicoid, so these seem to balance out...
Also strange is a copper shim ahead of the front element, any idea what its purpose is (it does not seem to have any bearing on focus travel)?