This is a detector test carried out by a UK detector dealer who is well known and reliable, he has had access to almost every detector known and tested them in his test bed (not air tests), Check out these two tests to see how a couple of Deeptech vistas did!!
http://www.staffsmetaldetectors.co.uk/5_pence.htm
http://www.staffsmetaldetectors.co.uk/cut_quarter_of_a_hammered_penny.htm
http://www.staffsmetaldetectors.co.uk/5_pence.htm
http://www.staffsmetaldetectors.co.uk/cut_quarter_of_a_hammered_penny.htm