SteveP(NH)
New member
Southwind said:Air tests are worthless indicators of how machines will do in the ground !!
I don't agree. My experience has been that an air test is a good indicator of a detectors POSSIBLE depth ability. Of course ground conditions determine the final depth, but you can get a basic idea from an air test. I've done air tests on every detector I've ever owned and WITHOUT exception, an air test gave a general indication of the depth you might expect in the ground. Of course I do have fairly mild soil, but never the less, it was accurate enough that I could estimate fairly closely what to expect in the ground from an air test.
An air test is simply a best case scenario. Only under very special condition will you ever get better depth in the ground than in the air.
The point that I was making is that an air test only tests about 10% of the factors that determine how good a machine will perform in the ground. If your air test results are the same as your test garden results then you have never tested a cheap detector. You can get good air test results on those cheap ebay detectors but they won't get much depth in ground with any appreciable mineralization. The air has no response, the ground has a response that totally dwarfs a target signal. A good detector can pick the tiny, tiny target signal out of the roaring huge ground signal, which is what gives it depth, a less capable detector doesn't have the signal to noise ratio that allows it to pick out that tiny target response from the overwhelming ground response. But none of that is tested in an air test thus an air test is not a good test for a detector's depth in the ground. You are lucky to have such mild soil but most of us do have to deal with more mineralization and a good detector can handle that, and a cheap one can't.
Perhaps a quote from Dave Johnson about the T2 he designed would also help to illustrate my point. Dave said and I quote, "The really hot machines out there (many of which I had a hand in) air test well past 10-inches, but lose a lot of targets in the ground. So rather than go for broke on air test, we decided to make it merely ruthlessly competitive on air test, and concentrated our efforts on pushing the state of the art performance on things that matter in the ground like target separation, iron rejection, and stable target ID."
But back to the title of this thread - which stated that the AT PRO equals the T2 and F75 - it very well might just do that, which is why I have pre-ordered one but an air test isn't going to provide the data to see if that statement is true or false.