Bill Watson's Gold Ring Vdi Chart, With Notes From Steve H

[Mical]

1 hour ago, DOOGY-MD said:

Wow! Thank you Mical!

Great work!

It looks like the Deus VDI numbers are closest to my F19.....for some reason...

It may have something to do with the F19 being a 19kHz machine vs 13kHz for the F75.  I don't remember which default program I was using with the  Deus and the frequency it was on when I did the testing.  I was using an X35 coil and I believe  VDI normalization is defaulted to on,  so the VDI would be normalized to 18kHz.

[GB_Amateur]

Detectors have a different location of the ferrous/non-ferrous breakpoint.  On the Fisher F19 it's 40.  On the Fisher F75 it's 15.  On the ML Equinox it's 0.  (I don't know where the breakpoint is on other detectors being discussed.)  Detectors also have a max VDI value (99 on the two Fishers just mentioned; 40 on the Equinox).

Thus trying to line up VDI numbers without accounting for the above key values (or other well-known values such as widely available coins) is going to result in a distorted/confusing  picture.

[Steve Herschbach]

On 2/23/2022 at 8:23 AM, Mical said:

This may be useful if you want to compare the F75 to some other detectors.

An interesting aside to this chart (thanks Mical) is the target id spread, highest to lowest.

CTX 3030 12.31 - 12.01 = 30 points

Equinox 800 19 - 6 = 13 points

White’s V3i 48 - 9 = 39 points

XP Deus 73 - 39 = 34 points

F75 SE 53 - 21 = 32 points

The jewelry target id resolution is a combination of the available numbers, and the frequency. Higher frequency reporting expands the results in the gold range, lower frequency reporting compresses it.

This degree of target id resolution usually does not matter, as most detectors will find the same targets. However, if working in modern aluminum trash, more target id resolution can help isolate and reduce certain very prevalent trash items, while reducing the risk of missing good targets. Let’s say after digging it all for a while, you note one particular pull tab being very common at a site. A detector with a high resolution will allow you to notch out that one target, while still getting most of the good targets. A low resolution machine has a higher risk of knocking out the good with the bad. Target id numbers are sometimes referred to as “bins” to highlight the fact that certain items are grouped together, and tossed in the same basket or bin, i.e. lumped together under one number.

In general I advocate digging everything, but sometimes there are limits on the time available to hunt a given site, and wasting time digging certain trash targets can cost you that valuable time. Sometimes it’s better to notch, to improve the odds. If one is doing so, using a detector with good target id resolution is important. This highlights a weakness in the Equinox 800. In general, I have found White’s detectors to be good for this, which is why I still own a Whites DFX. I run mine in unnormalized 15 kHz mode for even greater target id resolution than is the norm with most White’s models, which are usually normalized to 6.59 kHz for continuity purposes. More on target id normalization.

On 2/16/2022 at 4:49 AM, Geezer said:

It may be more to do with size and mass of the rings than conductivity. I am sure no expert, but that is what I see on the ones I find. The thinner, smaller, finer rings tend to hit lower VDI while the large heavy men’s rings hit higher and harder.

Low VDI for me are sure pretty, but they do not weigh up.

Good observation, and yes, this is generally why mens rings, and womens rings, fall into two different target id ranges. Womens rings below nickel, and mens above nickel. Size matters most with target id, and is modified secondarily by composition. Shape and orientation come last in the order of prevalance, not though necessarily in magnitude of effect.

 

[phrunt]

This is exactly what I've noticed in my sports field coin location, with my Nox/Vanquish the pull tabs came up the exact same target ID as the silver threepence coin (17), on the CTX I can ignore the likely pull tab number and still dig the threepence number with some confidence as their air test ID's are different.  With the Nox my method was the depth of the target, if I had a 17 Target ID and it was very deep I dug it with the likelihood of it being a silver coin, if it was more of a shallow 17 I rejected it with it likely being a pull tab.

With the CTX giving more more target ID information combined with the depth of the coin I'm finding I rarely waste my time digging pull tabs to get the deeper silver coin and I'm digging more silver coins because of this.  Having two data points to differentiate to make my decision between the two targets rather than just the depth on the Nox has proven to be very beneficial in an area I don't want to pop a lot of holes for bad targets.

[maxxkatt]

On 2/6/2022 at 10:58 PM, Trench1 said:

I thought I would add some more published information about Fisher's discrimination scale and gold rings. I still have my Fisher CZ6a and wouldn't mind finding a hot CZ5. It has been my best detector on nickels and gold rings. Ideal discrimination scale that I wish would be revisited with modern tech.

on #5 on ocean beaches. gold rings do travel together with coins. The ocean tide, currents and winds will sort metalic objects according to their specific gravity. This is why you will find coins, rings, lead weights in one area and bobby pins, light fishing tackle, pop tops in another area. If finding the later, move to another area until you start finding the former.