My old 28-90 Series 1 lens. I once used it extensively as it was very sharp, until it spent about 7 hours underwater in a flipped raft on the Rio Bio Bio in Chile. Got it out, it was full of water and fine grit. Didn't use it thereafter for 15 years. Pulled it out last year, the aperture is rusty, but still snappy, and it has lots of water spots internally. Mechanically, it still works perfectly (a testament to its build quality). Tried it and found it now produces images with a pronounced soft glow. Actually, I should try using it more often now!