Re: "owned the longest and still do:...90mm f6.8 Grandagon-N perhaps, but for many years I had a fair turn-over in lenses, not the least because I changed from 4x5 to largely 5x7. If I hadn't, I'd still have my 135mm Symmar-S, soon the Grandagon is probably going to go as well, although it is an excellent lens. Much of my more recently acquired glass is actually of MUCH older vintage.
PS: Generally speaking, I don't "do" my lenses.
"Whether you think you can, or think you can't; you are right."
Hey Mr. Hoegh, I am a native of Schenectady NY.
Only in Schenectady (home of GE) would one find a LF lens out in garage sale table.
1997 Schneider 150mm Componon S enlarging lens.
Beverly Hills, CA (albeit a 99%er)
The lens I've had the longest that I still use is a 1958 50mm Leitz Dual Range Summicron that I've owned since 1976. A year later I bought the large format lens that I now have had the longest and still use regularly--a 90mm f/8 Fujinon-W. It was not my first LF lens, but the previous ones are long gone.