If they have no scratches on the lens, and no severe gouges on the body, then it's pretty difficult for there to be damage elsewhere.
One thing to look at, is whether the internal lubricants have leaked, smudging the internal glass elements and/or aperture blades. This was common with really old (1970-1980s) lenses, but I don't know if it still happens.
It comes about as a result of improper storage -- lens on its side, in hot conditions, rather than lens standing up in cool conditions.
A good way to check for lubricant transfer (usually from the helicoid) is to put the camera on the body and do a long exposure with the aperture set to f/16. Check and make sure the aperture blades are free of oil- any oil at all could make the aperture blades get "slow" over time.That would manifest itself in Error 99's on EOS lenses I think.
Previous Topic
Index
