12 years ago I purchased a lovely 50-500mm Sigma lens. And used it with great pleasure for a number of years.
Unfortunately, one day gravity and I disagreed, and I shattered the UV filter on the lens. The glass stayed intact,
but I could not remove the filter. I put it away for a while - a while that turned out to be several years, and finally
got around to sending it to Sigma this last month for repairs.
Turns out they don't service lens that are over 10 years old. Now, that's a new one on me, and it may be to others.
I asked the tech at Samy's Camera here in San Francisco if he could pry the lens filter off, and after very careful tries, he got the
glass out, but not the rim. However, the lens now works just fine - no thanks to Sigma.
While I certainly accept my mistake in waiting to have the lens repaired, it never occurred to me that Sigma (or anyone else)
would simply refuse to repair it because of time constraints.
So, in this digital era, don't depend on Sigma (and perhaps others) to repair anything 10 years down the line.