Hi Gerry, No F 5'ers speaking up so I will give it a try. F5 owners are not alone in relying on the confidence meter for deciding weather or not to dig. A bunch of us F5, F70 and F75 swingers are very dedicated to using all the tools our Fisher F series are equipped with. Digger27, myself and many others around the web are quick to share info with each other vital to the learning experience with these much alike F series formats. Much of our information will hold up with many different F series models.
One the thing confidence meters and VDI will do is help decide if you are directly over a target or off to the side somewhat. Many high tones can come from rust off of big iron. Even if iron is notched or discriminated out, look to see if the iron icon lights up when getting a non repeatable high tone. This is likely a false signal and drive VDI and confidence meters nuts.. I know from past conversations with Digger, he and I both dedicate a significant amount of effort making sure the target is placed as close to directly under the coil as possibly. This is important in an accurate determination of the target. Confidence meter can help you in determining weather or not you have done that. An example may be a solid reoccurring signal, one way, only off to the side of the target reading 6" deep. This target will probably have a jumpy VDI and will most definitely have a low indication on the confidence meter as the two seem to somewhat go hand in hand, to a point. By examining this target further and getting more over it's center, lets say you now get another hit from a 90 degree angle. So now you have a two way hit in both directions 4" deep, notice we are now hitting target 2" shallower than with the one way hit. This tells me I am close to being directly over the target. But wait, my VDI still jumps from the high 60's to a 71 or 72. Typical symptom of a very corroded zincoln. With the F70, the longer I examine these type targets, the higher the final numbers seem to get. Close to 71 or 72. But the confidence meter is still as jumpy as when I started. This tells my 99% it is a corroded Lincoln cent. If the same scenario ends up being a 73 with 2bars in confidence meter it is probably a corroded clad dime or a non corroded pre 1984 penny. If it is a 73 solid with a full confidence meter it is a very clean clad dime and a 75 and full confidence meter would be a silver dime with my 10" elliptical coil. Your coil and soil type will vary these numbers somewhat but the theory should still apply. I hope this makes some sense----HH-IM