There does remain the problem of what to do with lenses with non-standard filter threads (or none). I have 2 barrel lenses on Sinar panels where I have superglued a Cokin holder to the rear of the panel, leaving the front free for an add-on shutter, and I did even superglue a stepping ring to the front of a 168 mm Angulon so that I could use standard filters. This particular lens had a front which was too small for my standard oddball filter solution, which is a Cokin filter holder with 3 pinch screws instead of a threaded ring.

I am sure Donald is right in suggesting that T-mount adapters can seize onto lenses. My worst experience of aluminum corrosion of this kind was changing the plug on a lawn mower which had a Briggs & Stratton engine. The plug had been in for about 3 or 4 years, when I unscrewed it the plug came out complete with the plug hole and a disk of surrounding metal 3 or 4 mm thick. This was one of those few occasions when superglue was not able to effect a repair

Regards,

David