Making new AT Pro VDI numbers video, have a question..:shrug:

[Diggin-it]

Several years ago I made a video demonstrating the VDI numbers the AT Pro displays for various valuable targets. That video got quit a few hits and positive remarks. However there were several people who complained that it was not accurate since the targets were on top of the ground and not buried. Here's a link to the original video:


So I decided to film a new video this time burying all the targets. My question is what depth do you think it would be best to bury them at? Remember this will not be a video about how deep it will detect the targets, rather a video to see how the target VDI may differ from the original video. My thought was to bury them at 3 inches, what are your guy's thoughts? The soil around here ground balances at around 85.

Here's the Tweet I sent out tonight, has a picture of all the targets weighted and tagged ready to bury. Man that was a pain and now I have to bury them...argh.



I will actually be filming 4 different videos, 3 different coils on the AT Pro to demonstrate if VDI numbers vary with the different popular Garrett coils and then also filming a video with my XP Deus.

 

[John-Edmonton]

I would just bury them a couple of inches. It's pretty hard trying to re-create a silver/copper coin that's been in the ground for many years. ID numbers will change over time as oxides build on the coins surface. Designating numbers/icons to targets is far from an exact science. There are other variables affecting the ID of a target such as it's orientation to the coil, the depth (deep coins won't display proper id), moisture in the soil, mineralization...there are many others. So, your first video was probably a good base line for targets. If you learn your detector well, you should be able to compensate different variables and come up with a fairly accurate guess as to what is underneath that coil.

So, if you bury your coins a couple of inches, you should get some slightly (but no a whole lot) different ID readings. People who have thousands of hours experience are well aware of the changes in ID for the same target in different environments. It is the newer people that suffer a lot of frustration over target ID. There is no universal way to get the same target ID on the same target. Considering most targets are in the top 2-3 inches, your air tests (coins on top of the ground) were probably the most accurate.

Some people think air tests are absolutely useless. Nothing could be further from the truth. An oxidized penny will read different then a pristine one. Even the depth result give us a lot of good information. An air test of a target will show you the maximum potential depth that a target will read. Of course, you will get less depth when you bury targets, as you are now introducing a matrix with some mineralization, moisture, salinity and other extrinsic factors. Plus.......if a target air tests 4 inches in the air, it will definitely not read any deeper in a soil matrix. In fact, it will read less.

If I had 2 different metal detectors, with the same sized coil, and similar settings, and an air test for a penny read 10 inches on one and 8 inches on the other, I would definitely buy the one which read the penny at 10 inches.

Personally, I prefer an air test as a target ID as baseline data, as that will probably be the closest ID I will have to similar targets in the top 2-3 inches. Any targets reading deeper, and give a reasnable audio in all directions will be dug anyways, as some very expensive jewelry can show up with odd ID numbers.