Very good read and testing, thanks for sharing. I've got one question though about the test pool of rings you used...Were these rings selected randomly from "non-finds" that friends of family own, and not found via a detector? Reason being that I've seen people use test pools of rings in the past to try to judge VDI/discrimination patterns, and often these rings in the test pool to do the number crunching were found with a detector. In that case, despite best intentions, people tend to dig or favor certain zones when ring hunting, and thus that ends up biasing the resulting numbers derived from the test pool.
A friend has found well over 100 gold rings water hunting over the years, scooping each and every signal he ever comes across above iron. No matter how sick sounding, "foil-sh", or etc...He never passes up a hit and always recovers it, and these rings were recovered at various sites, ranging from "low income "neighborhood" beaches, to beaches more frequented by middle class or even well off patrons in some areas. For all the above reasons, and in particular recovering all signals above iron, we felt this test pool of rings was about as unbiased as it could get in terms of a truly random test pool on which to graph some conductivity numbers.
I have seen a few such truly random test pools graphed as well in the past which pretty much jived with our numbers. What we found was that fully about half of all gold rings read well down into the foil range, below nickel. We also then graphed a random test pool of round and square tabs for comparison of certain conductivity zones. This was done on a machine with high conductivity resolution, where not only do 99.9% of all tabs tested span a 20 digit wide VDI range, but also on this particular machine nickels are distinctively lower in VDI # than tabs. There is about a 5 digit VDI separation from the highest nickel VDI # (the nickel zone spans about 10 digits) and the lowest tab #. This way we could also truly test the old rule of thumb saying that to find gold rings you must "dig the nickel zone", or that most gold rings read in the tab range.
With high conductivity resolution in the low to upper mid range of the VDI scale, we could then see if there was any evidence (at least with our test pool of rings) to judge the realities of such sayings among detecting circles that we've all heard for years. What we found, besides about half of all these rings reading in the foil range below nickel, was that there was no larger concentration of rings in the "nickel zone" or the "tab zone" than anywhere else on the scale. In fact, we found there was a surprising amount of gold rings that read well into the coin range, from say just a hair below a zinc penny, which in turn is just a hair above the highest tab reading, to all the way up into the higher coin range.
So, why the old rule of thumb saying that if you are after rings then dig the nickel zone? My theory is that on machines with low resolution in the low to mid range of conductivity, have a much wider window of what they consider the "nickel zone", stretching far below into foil, and far above into the tab range. And, besides this larger "net" to catch more rings that a machine says are in the nickel zone, people always heard to dig the nickel zone when searching for rings, and so that zone was targeted more and others passed, which in turn would further support the theory of digging that particular zone when after gold rings.
Yes, all that said, if I'm old coin hunting for the day, even I won't pass up a nickel signal in the hopes of a gold ring. That concept of digging the nickel zone has just been driven too hard into my head over the years.
The way I look at avoiding certain zones of conductivity and digging others when after rings on land is this- When you go to Vegas you don't bet all out on every hand. Instead, you hold back your money and put more of it on cards you are holding that have a greater percentage of paying off. I look at ring hunting on land in the same way- That if I'm at a site loaded with tons of tabs, instead of making it my life's work to dig all those tabs, I'll instead avoid those and dig all VDI #s even 1 digit off from them. It's the trash to treasure ratio thing- Most common trash target at a site? At many that's going to be either round tabs, square tabs, or both in combination.
So the realities are that for every gold ring that reads in that range of VDI, there are going to be hundred if not thousands of tabs that you have to dig first to find them. I feel in a situation like that that the better use of my time is to go after all the other gold rings that read outside that tab range. In this case, I will target the foil and nickel zones, and that little gap between the highest tab # and where zincs start (if zincs and other clads are all over the site as well). Conversely, if a site is loaded with foil but not much in way of tabs, or at least only seems plagued with a few specific kinds of tabs, then I'll avoid the foil range and dig the nickel and tab range instead.
It's all a matter of how much trash exists for that span of conductivity, versus any potential gold rings that might lurk there in any zones of conductivity. Yes, digging it all is the only way to recover rings, but with the right selective use of VDI avoidance, you can at least improve your trash to treasure ratio and recover a vast majority of the gold rings present at the site, and leave the few behind that would entail digging tons of one specific type of junk commonly found at that site, in order to recover that smaller percentage of rings still left behind by being selective.
Also, more important than what zones of conductivity to dig, is going to be just where you dig. Instead of avoiding tabs at a tab laden site, I might just pick one small 12 foot square area of land in a likely open spot to toss a ball or Frisbee, and then dig every signal above iron out of there. This kind of thing though needs to be done in stages so as not to leave the site a mine field. When I'm in the mood to do it, I'll dig all the solid hits first, such as ones not sounding sick in audio, and then come back after the ground has healed and dig others I felt like passing up the first few visits.
Besides finding rings, you're apt to unmask some nice old silver coins, because detection fields stop and only see the first (meaning shallowest) metal object that touches any part of the field. Just can't get around that, and the deeper the coin in perspective to the shallower trash, the further to the side that coin can be and you still have no hope of seeing that coin. Even the outer edges of the field touching that shallower metal means the machine is never going to see the deeper coin.
Another strategy for ring hunting on land is to travel back in time further than the common trash. If round tabs (being older than square ones) range down to say 6" in depth, then start digging any "tab" signals that sound deeper than the tabs there. I saw a friend dig half a gold ring at a site last summer using this strategy. It had been hit by a lawn mower and cut in half, and he said it read well down into the foil range. When I asked why he dug it, he said it was deeper than the foil found at the site. In other words, older than when foil began to be used in common practice at this particular park.
Other often overlooked areas (besides obviously sport fields)? How about the grass strip at the edge of parking lots in parks and at other sites. Often people are reaching into their pocket for their keys as they approach their car, and as they pull their hand out of their pocket they slide a ring off by accident. Or, they had the ring in their pocket while they were cooking out, playing ball, or taking a swim or such, and out comes the ring when they grab those keys. Same deal with silver coins. Often the grass right next to the parking lot at "dead" parks is loaded with trash so most people avoid it, but if you take the time to work those spots real slow, or maybe even dig all the "trash" out of there, you'll find rings or old silvers that others have missed for years.
When I'm ring hunting, besides avoiding specific VDI #s that are too numerous for the time I have at that site, I'll also use the audio and further aspects of the VDI to judge a target worthy to take my chance on. If I change angles over the target and it roams by 3 digits or more, then I suspect it's odd shaped trash, where as a round target like a ring or a coin will usually hold to 1 or 2 digits no matter what angle I sweep over it (all dependent on VDI resolution of a machine of course to see these distinctions). As for the audio, with machines capable of telling you long fine traits of a target (a thing Tesoros, among a few other machines, are noted for), then I'll listen for that "round" or "boing" or "quality" or "smoothness" of the signal and dig those, and will avoid the ones that sound sick, harsh, rough, scratchy, hollow, bangy, or fuzzy. In all the rings we tested, only a handful of them (perhaps 6 or 7) had a sick sound and were jumpy in VDI. These rings were either cracked and no longer a complete loop, or they had very fine "spider webbing" that scatters the eddy currents of the detection field.
Yes, not all rings, based on orientation in the ground, are going to give you a solid hit and might sound like trash, and yes...there is a lot of trash out there that can sound very of "quality" like a ring *should*, but just the same in broad general strokes most rings should sound good (being an intact loop), and there is a lot of trash (especially odd shaped trash) that sounds sick. Not saying there aren't many exceptions to these rules of thumb, just that audio can be useful on days you want to be real particular about what you are digging, trying to once again increase your odds of that "trash to treasure" ratio thing.
Here's a thread link to the large ring and tab pool graphing we did. It contains various charts graphing in different visual ways to illustrate just where these rings fall. I've had some tell me that most gold rings don't read in the foil range. All I can say is this test pool was as random as humanly possible, and that I've also seen other non-biased ring test pools that had similar findings- that roughly half or more of the rings read in the foil range, and that no greater number reads in the nickel or tab range. Keep in mind though that a wider window for certain zones on certain machines might change that perspective, as obviously a wider nickel or tab zone is going to entail more foil or other trash (and thus ring)...
http://www.findmall.com/read.php?21,1720979,page=1
Very much enjoyed this thread and the testing and remarks. Somebody is always trying to beat the odds in Vegas, and we all seem to hear of people with some very odd beliefs or superstitions that always seem to be winning. Regardless of whether their methods are based on solid principals or not, the very fact that they are just trying something different could be reason enough for their success. That's the way I look at ring hunting on land- Real or imagined, any change in approach as to what others have always done before you, might equal success by just share virtue of doing something different at a site, and so digging targets others might otherwise not when after rings. Heck, even picking a random VDI range of say a tight 20 digit span, for no rhyme or reason, and just saying "Today I dig it all that reads between these two numbers", will produce results. No longer are you doing what all others before you have at that site, like say most people seeming to concentrate on digging the nickel zone, and now you are bound to find a few things that others simply never thought to dig.