I took the shot below at the Six Flags park in Vallejo, CA a while back and was really quite surprised with how it turned out. The picture isn't anything special, but the shot was taken through a chain link fence and I find it hard to actually see the fence. It was a black fence which helped and it was closer to me than to the lion, but I was still probably 10 feet from the fence and the fence was probably 30 feet from the lion. I guess going for a shallow depth of field really helps.
PC
Here's the larger size