This is a repost from this thread in the Tesoro forum...http://www.findmall.com/read.php?17,1846706,page=1
Where Tabman wanted to know where foil drink tops read on the 180 Sovereign meter, so he could see how many rings that might cost him in our 121 random gold rings chart if he discriminated them out, due to those foil tops being all over sporting fields he hunts. He mentioned too that there is a bunch of other trash that read below those foil tops for him as well, so if he could set his discrimination just high enough to kill foil drink tops he could avoid a ton of trash so long as it didn't cost him too many rings.....
.....Hey Tabman, I scanned the two foil caps you mailed me, looking identical to these you had posted a picture of prior...
[attachment 258041 SportsDrinkCaps001_zpsba03d727.jpg]
Which I would assume perhaps came off these sport drink bottles you posted a picture of before as well in this related thread in the Teknetics forum you started here...http://www.findmall.com/read.php?58,1857526,page=1
[attachment 258042 gatoraid_zpsde09d47a.jpg]
You mentioned you are finding these foil tops as the far most numerous trash item at sports fields you hunt, so it would make perfect sense to me that the above picture you posted of a sport drink is the most common source of those foil tops you are finding. Probably other sports drinks with the same type of tops as well. I know I've seen similar ones on non-sport drinks but can't off hand place just which drinks I've bought in the past that have them.
Now we can do what you were shooting for...To know just where those foil tops read in VDI on my machine in relation to our lowest gold ring numbers in those 121 rings we graphed, and also re-scaling the Teknetics Gamma 2 metal detector's VDI to the Sovereigns 180 meter for various conductivity zones. More to the point I think of what you were asking in the first place, is if you calibrate your Tesoro's notch or disc dial to just kill those foil tops, how many gold rings might that be costing you percentage wise according to our charted VDI numbers we crunched? In this thread is all the info on those 121 truly random rings used in the test pool we scanned, which also contains links to various other threads in which people have shared their methods and ideas for finding rings on land...http://www.findmall.com/read.php?21,1720979,page=1
So where do these foil tops read in comparison to our lowest gold ring VDI #s? The two foil tops you sent me of the type you posted pictures of prior, you had marked as both reading #48 on your G2 using the 5" coil. On the Sovereign every meter has a calibration pot to set it to go 180 on a dime or quarter when you switch coils, thus all coils used, big or small, will read the same exact VDI # for anything on the scale of conductivity once calibrated properly. Does your G2 change it's VDI a bit based on coil choice?
Either way, I only wish you had marked these two foil tops #1 and #2, because while they both read 48 on your machine, the Sovereign has extremely high resolution from small foil all the way up to the copper penny range. Point being that while both of these foil tops are in good shape and appear to be from the same manufacturer (?), they both have slightly different VDI #s. If you had been marked them #1 and 2 based on manufacturer I could have noted #1 or #2 so you'd know which of them from read what so that you could get even finer hair line adjustment on your discrimination or notch dials (whichever you are using on the Tesoro). Regardless, they are so close in VDI that that probably won't matter much, and by shooting for the highest VDI # I read of the two you'll insure you are missing the other lower reading one as well. Just scan over several similar looking foil tops as you make your adjustments until all are silenced. So here are the results...
Both foil tops for you read 48, while for me using a 180 scale meter on my Sovereign, one foil top scans in as a VDI # of either 86 or 87, while the other scans in as a VDI # of 89 or 90. I repeated this test numerous times on both, sweeping from several angles, and allowing my machine to "warm" up about 5 minutes to be sure the meter's calibration pot was set precisely to go 180 on a dime, so that the resulting #s would be as precise as possible.
Now we get to where the rubber meets the road for you...So, refreshing our memory on where the smallest/thinnest/plainest of over 121 gold rings read, meaning what was the very lowest VDI #s we scanned with all those rings, the lowest # being that of...75. Here, I'll repost the chart for you to look over from the prior "A condensed splitting hairs on rings thread" link I posted where we crunched all these numbers...
[attachment 258043 SovereignGTGoldRingChartJPEG.jpg]
If you just high ball it to the highest of the two foil top numbers I got from the two, that would be 90 in VDI. OK then, so if you raise discrimination high enough to just barely knock out that foil top, exactly how many of the 121 gold *truly random* gold rings will you be missing? The grand total would be 9 of them, and note that all those 9 are small gold rings, and further still yet 4 of those 9 are white gold, which tend to read very low in VDI due to the materials usually mixed with them to give them their color (IE: Probably nickel as one possibility, which will drag the VDI # down).
Also, notice that white gold rings are far less common than yellow gold, and that all 4 of the white gold rings classified as "small" in are chart that will be missed are the entire sampled small white gold rings we charted. If somebody has you looking for a small white gold ring for sure you would not want to disc out the foil tops to try to find it. But, when just huntiong for rings on land, if you look at the chart as a whole, white gold, and in particular small white gold, isn't very common, so by discing out the foil types you are leaving behind a far lower percentage of possible rings (by our numbers if not anybody else's of course).
So there you have it...Not only can you re-scale our VDI scaling to your G2 of various zones, but you can also now calibrate your Tesoro's notch or disc to various zone cut off points as well. To see where your nickel zone begins versus mine, scan a modern nickel. On my machine it's typical nickels read right around 143 to 146 in VDI (most perhaps in the 144 to 146 range). 99% of all tabs I come across, both round and square, read from 149 to 169 in VDI range. Copper pennies such as wheats will usually read 178 or 180. Zincs for me usually 173 or 176. All coins above a copper penny in conductivity read 180. That may sound like a drawback but when I'm old coin hunting I don't care what kind of coin the machine thinks it is, as I've dug plenty of silvers in the past that read as clads or pennies on machines I've own that could split hairs on coin types. If it's deep I just want to know it's a coin, or if it's shallow but mixed in trash same deal, because somebody might have missed a shallow oldie. Dry conditions, minerals, being on edge, masking, the coin being worn badly...All these things I've seen cause silvers to read as some other coin in the past.
Now you just have to decide- Is giving up those potential 9 rings worth raising discrimination to just barely kill a foil drink top? Depends on the amount of trash at that VDI and lower in conductivity. If it's there by the thousands then yea I'd ignore anything lower myself. All a matter of productive use of time while trying to swing odds in your favor, as to which zones I might ignore and which I might dig, all depending on how much of what kind of trash is present in those given conductivity zones. IE: Digging 10 thousand tabs just to recover a small percentage of rings you'd might miss otherwise to me (on land that is) is not worth my time most days. Instead I'll ignore those and dig all else.
Or, if there is a ton of foil or other low conductors but not much in way of tabs, or say only a few specific tab #s that keep showing up, then I'll dig the tab range and all others and avoid the foil below nickel (say 140 VDI or lower) and dig everything above that, perhaps avoiding one or two pesky tab #s that seem most present at the given site. Same deal with zincs. If there are billions I'll avoid those when ring or say old coin hunting, willing to give up a possible ring or two or the odd old coin that reads as a zinc. All a matter of trying to slant the odds in my favor to decrease the ration of treasure dug versus trash. Also all depends on my mood. Some days I'll pick a small area and grid it out and dig all signals above iron.
One more thought...Besides the 4 small white gold rings (the entire span of those we scanned in being missed- 4 rings total in the chart), what of the other 5 of those 9 rings you'll miss? Those were classified as small yellow gold. Thinking perhaps no big deal to miss small thin gold rings since they don't have much gold weight to them? Consider first that many thin gold rings are the ones with diamonds in them. IE: Woman's wedding bands, although they might be a bit bigger usually than what we charted as "small" for those particular 9 rings, or maybe with the crown on them to hold the diamond they would read higher and these above were just plain super thin bands with no tiny crown on them. Can't remember off hand.
