Thank you Root and you indianbullet .
steve every statement you wrote is really helpfull.
I don't insist in using coin/relic timing ,Actually I used normal mode since bought my gpx and in an experience I could dug out a copper spoon in about 80 centimeter .
http://www.detectorp...ming-charts.htm
As I red this topic you atached in forum I thought about maximum depth gpx 5000 can operate in relic mode .
every operator has an aim in using detector in a particular ground , but like you said ground type is important to choose timing .
Because I search for large targets in depth and not to want dig out tiny targets near surface so I need to know what is my best setting ?