In message , Alan French
writes
Does anyone have an older Lumicon filter that is not in a ring that says
"Lumicon?" I know some filters I saw in the early days of light pollution
filters seemed to use rings from other sources.

We have a filter that is supposed to be a Lumicon UHC, but that is not what
the ring says.

A reasonable heuristic test of whether or not the ring is a Lumicon one
is whether or not the thread is a decent fit onto your eyepieces.
Lumicons filter technology was marvellous, but the mechanical
construction of their threaded carrier was always pretty iffy for as
long as I can remember.

Possible you have genuine Lumicon glass rehoused in a new correctly
threaded carrier. Best bet is measure it's transmission spectrum
photographically and compare it with the ones on Maurice Gavin's site.

Regards,
--
Martin Brown