I was testing different settings on a coin and a nail in the same hole but about an inch apart. I think I mentioned dime but it was a copper penny and a rusty nail. Sorry for the bad glare but I think you can still get the idea.
http://www.youtube.com/watch?v=KKlRfz0Q13M
http://www.youtube.com/watch?v=KKlRfz0Q13M