Bill, in my experience (which is limited compared to some) the more discrimination I use on a machine, the less depth in detection I can expect (generally). I've read that this has to do with the fact that the more disc. we dial in, the more we are asking our detector to do i.e. we are asking it to work harder, and one of the results of this is less depth. With regard to marginal targets, my experience is that at any depth, a target which is on the verge of being discriminated out may give a signal which is either unclear or broken, or differs in some way from being "good". There may be a number of reasons for this. e.g. the soil or mixture of soils where we are detecting, fire ash buried where we are detecting or another target close by which is being totally discriminated out by the detector. This can happen at any depth, but the deeper you go, and the more soil there is between the coil and the target, the more chance there is that we will pass it by because it only signals in one direction, or tunes out etc. If a machine has pre set ground balance, or is not quite tuned to the soil properly,the more chance there is that we will pass by that good deep target...more so if we are using discrimination. Sometimes it is good to switch to all metal to see what the target sounds like in that mode...if it is still deep, but more solid, then there is a good chance it will be a good target.
