Is it possible to set the discrimination to find everything from copper pennies and up and then set a real narrow notch for nickels only? Can the notch be set as narrow as you want? I want to try and dig mostly nickel signals without digging a lot of junk too. I know there are some things such as the little aluminum pencil tops and some tabs that cant be avoided but I want to get the notch as small as possible. I did not notice a pinpoint button on the face of the detector either. Does it have one? Can someone explain how the notch works. Thanks.....