I realized today that dept and size make a difference. Large pieces of aluminum read in the hi 60_low70s(flat buried cans) and the dept of the object also changes the reading some. Anyone else get the same response from their md? I'm using a f5. Been diggin a lot of trash in the 40-50s so I was suprised to get a can instead of a copper penny! I'm just confused because I had a good system going until this mornings hunt.