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  #1  
Old 12-15-2017, 10:36 PM
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Default Can you get more depth in the ground than in an airtest?

Just curious about this. I've heard people say their detector will only airtest x inches, but goes deeper in the ground. Then I read that a proper airtest is the max you can expect out of your detector. I know ground conditions are the determining factors for an object in the ground and EMI can really make an airtest go wonky. Is there a definite answer?

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Old 12-16-2017, 12:05 AM
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Yes, no and maybe???
But there probably isn't a way to prove either argument.

I know I've dug a couple coins with my old compadre that were definitely deeper than it will air test, but there are too many variables to say why how or when it happens. Ground conditions, ground balance, co-located targets, EMI and the list goes on.

I like to chock it up to good fortune when it happens, give thanks,
and keep on swinging.

If we could just get Steven Hawking to take a break from string theory and start designing detectors we could probably get some answers.

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Old 12-16-2017, 02:22 AM
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Yes, but the coin needs to have been sitting in the ground for quite some time (very broad time range, I know! ). There's this thing called a "halo effect" which is the result of ions from the metal seeping into the ground, therefore making the target appear larger than it actually is. When the target appears larger, the detection depth increases (duh!).

Do a google search on the halo effect, there are some good sites out there.

http://www.njminerals.org/metaldetec...aloeffect.html

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Old 12-16-2017, 04:04 AM
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Depends on the soil and how long the coin has been in the ground. Certain types of tough ground can hinder depth for a lot of detectors and an air test may get better results , but in other places or soil types/conditions , as long as the target has been there a long time its possible to get better depth than an air test. There are a lot of variables but it happens.

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  #5  
Old 12-16-2017, 04:17 AM
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Never heard this...
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  #6  
Old 12-16-2017, 09:20 AM
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Originally Posted by TabZilla View post
Yes, no and maybe???
But there probably isn't a way to prove either argument.

I know I've dug a couple coins with my old compadre that were definitely deeper than it will air test, but there are too many variables to say why how or when it happens. Ground conditions, ground balance, co-located targets, EMI and the list goes on.

I like to chock it up to good fortune when it happens, give thanks,
and keep on swinging.

If we could just get Steven Hawking to take a break from string theory and start designing detectors we could probably get some answers.
Originally Posted by X-Terra70 View post
Yes, but the coin needs to have been sitting in the ground for quite some time (very broad time range, I know! ). There's this thing called a "halo effect" which is the result of ions from the metal seeping into the ground, therefore making the target appear larger than it actually is. When the target appears larger, the detection depth increases (duh!).

Do a google search on the halo effect, there are some good sites out there.

http://www.njminerals.org/metaldetec...aloeffect.html
Originally Posted by ohiochris View post
Depends on the soil and how long the coin has been in the ground. Certain types of tough ground can hinder depth for a lot of detectors and an air test may get better results , but in other places or soil types/conditions , as long as the target has been there a long time its possible to get better depth than an air test. There are a lot of variables but it happens.
Originally Posted by snickers104 View post
Never heard this...
Thanks for the replies guys. Xterra: thanks for the link to that article. I just did a quick skim reading of it and it's very interesting. I bookmarked it so I can read it in depth later.

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  #7  
Old 12-16-2017, 10:10 AM
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Part of the answer also lies in whether or not you're talking about a machine that has Auto GB or not too. Machines that Auto GB need something to balance against, and air doesn't count, so air testing isn't at all an accurate gauge of what the machine can do in the real world.

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  #8  
Old 12-16-2017, 03:11 PM
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I'd imagine wet soil would help also with the dirt halo, that might help hit deeper than an air test.

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  #9  
Old 12-16-2017, 03:26 PM
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I will say this it might happen every now and then but ive never found a coin deeper than my machines will air test either with the at pro or deus... and if you guys look at my finds I hunt old sites and dig old coins where the halo would be present. I don't see people digging coins deeper than what there machines air test all the time. What I'm getting at is if you machine air test a silver dime at 7 inchs max don't think your walking around and its seeing them at 9 and 10 inchs and if you want to find them that deep on a regular basis you better get another machine....MAYBE and I say maybe you might find one at those depths if all the stars lined up perfect.. We don't see post in the finds forums of people boasting about deep coins with detectors that are not known for depth.. If you looking for deep coins better to have a detector that will reach down there and get them instead of depending on the halo effect.

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Old 12-16-2017, 05:56 PM
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Originally Posted by X-Terra70 View post
Do a google search on the halo effect, there are some good sites out there.

http://www.njminerals.org/metaldetec...aloeffect.html
Awesome link, X-T! Bookmarked that one - fantastic overview of halo effect and its wide impact on detecting, from test gardens to detecting after it rains.

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  #11  
Old 12-16-2017, 07:19 PM
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Originally Posted by calabash digger View post
I will say this it might happen every now and then but ive never found a coin deeper than my machines will air test either with the at pro or deus... and if you guys look at my finds I hunt old sites and dig old coins where the halo would be present. I don't see people digging coins deeper than what there machines air test all the time. What I'm getting at is if you machine air test a silver dime at 7 inchs max don't think your walking around and its seeing them at 9 and 10 inchs and if you want to find them that deep on a regular basis you better get another machine....MAYBE and I say maybe you might find one at those depths if all the stars lined up perfect.. We don't see post in the finds forums of people boasting about deep coins with detectors that are not known for depth.. If you looking for deep coins better to have a detector that will reach down there and get them instead of depending on the halo effect.
My thoughts and findings are exactly identical...thanks for keeping me from all that typing.
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  #12  
Old 12-16-2017, 08:18 PM
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I will say this it might happen every now and then but ive never found a coin deeper than my machines will air test
+1

My results as well.

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  #13  
Old 12-16-2017, 08:58 PM
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Originally Posted by calabash digger View post
I will say this it might happen every now and then but ive never found a coin deeper than my machines will air test either with the at pro or deus... and if you guys look at my finds I hunt old sites and dig old coins where the halo would be present. I don't see people digging coins deeper than what there machines air test all the time. What I'm getting at is if you machine air test a silver dime at 7 inchs max don't think your walking around and its seeing them at 9 and 10 inchs and if you want to find them that deep on a regular basis you better get another machine....MAYBE and I say maybe you might find one at those depths if all the stars lined up perfect.. We don't see post in the finds forums of people boasting about deep coins with detectors that are not known for depth.. If you looking for deep coins better to have a detector that will reach down there and get them instead of depending on the halo effect.

Browsing enough of these forums for long enough you see so many claims of coins being found at unbelievable and even unreasonable depths with detectors not known for depth. A certain percentage of those can be attributed to embellishment or error , but a certain percentage..... especially from experienced detectorists not known for fish stories.... are true. Another reason why certain isolated " tests " do not necessarily always match what you might experience hunting various places out in the field.

I am going to make you roll your eyes here , but I have certain areas where the soil make up and other variables make it virtually impossible to detect and identify a long buried quarter past 6 or 7 inches.....while at a particular spot that remains wet much of the year I have detected and identified 3 separate long buried quarters laying on top of a clay layer 12 inches below the surface of the topsoil ......and with a 5x8 Garrett coil !! and that exceeds air test results " Impossible " you might say , well I would agree with you if it had not happened. They were all coated with a green/black , wet " halo " from being wet much of the time and interaction with soil minerals. Say what you want , but that illustrates a pattern between soil , target , and detector , that has to be happening all the time....just usually so subtle you don't notice it. As soil composition , moisture , and various other variables change , so does the detection field to some extent. There are places it can even change drastically in just a few feet , and we are blissfully unaware of it.

Doubt if you want , I wont be upset. I'm 47 and have been detecting since I was 18 , yet I am often surprised by things I didn't think possible before.

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  #14  
Old 12-19-2017, 09:55 AM
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No I didn't say it NEVER happened... look at what I wrote I said if all the stars lined up just right it MIGHT happen. All I was saying is I hunt old sites where the halo would be present on deep coins. I have dug deep coins on these sites but NONE deeper than my machine will air test. Others have had the same results as you see in their post. I know there are deeper coins on some of these sites because we have dug king George coppers out of the pits.. I also dig copper relics all the time and a lot are very deep but NONE past what my machine will test on it. My hunting partners been doing this 30 years and I have never heard him tell of some super deep coins that were well beyond his machines depth capabilities. I would imagine hes dug hundreds of coppers and Spanish silvers combined. All I'm getting at is its NOT the norm ,if it was I would have seen it and he would have too, and the other guys above would too. FOR EXAMPLE The DANGER is some who believe this are running around with a 5 x8 on their at series detectors and thinking its seeing 12 inch silver quarters and dimes on a regular basis and its not..... and other detectors that don't have depth are not either....AGAIN when some certain phenomenon happens or it MIGHT happen, but this belief that its a regular occurrence and a detector that wont air test over 8 inchs on a silver dime is seeing them at 10 inchs on a regular basis is bogus IMO.. They can write all the articles they want but I'm in the sites where the age is there for the HALO to be present and down here in Calabash the halo hasn't showed up yet and in 30 years of my partner detecting I would think he would have seen it 1 time at least on a old coin.. We can all agree to disagree and like I said above if you want to find deep coins then buy a machine that has some depth to it because if your waiting on the halo to help you out you might just get your feelings hurt.
Originally Posted by ohiochris View post
Browsing enough of these forums for long enough you see so many claims of coins being found at unbelievable and even unreasonable depths with detectors not known for depth. A certain percentage of those can be attributed to embellishment or error , but a certain percentage..... especially from experienced detectorists not known for fish stories.... are true. Another reason why certain isolated " tests " do not necessarily always match what you might experience hunting various places out in the field.

I am going to make you roll your eyes here , but I have certain areas where the soil make up and other variables make it virtually impossible to detect and identify a long buried quarter past 6 or 7 inches.....while at a particular spot that remains wet much of the year I have detected and identified 3 separate long buried quarters laying on top of a clay layer 12 inches below the surface of the topsoil ......and with a 5x8 Garrett coil !! and that exceeds air test results " Impossible " you might say , well I would agree with you if it had not happened. They were all coated with a green/black , wet " halo " from being wet much of the time and interaction with soil minerals. Say what you want , but that illustrates a pattern between soil , target , and detector , that has to be happening all the time....just usually so subtle you don't notice it. As soil composition , moisture , and various other variables change , so does the detection field to some extent. There are places it can even change drastically in just a few feet , and we are blissfully unaware of it.

Doubt if you want , I wont be upset. I'm 47 and have been detecting since I was 18 , yet I am often surprised by things I didn't think possible before.

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  #15  
Old 12-19-2017, 10:55 AM
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Originally Posted by calabash digger View post
I will say this it might happen every now and then but ive never found a coin deeper than my machines will air test either with the at pro or deus... and if you guys look at my finds I hunt old sites and dig old coins where the halo would be present. I don't see people digging coins deeper than what there machines air test all the time. What I'm getting at is if you machine air test a silver dime at 7 inchs max don't think your walking around and its seeing them at 9 and 10 inchs and if you want to find them that deep on a regular basis you better get another machine....MAYBE and I say maybe you might find one at those depths if all the stars lined up perfect.. We don't see post in the finds forums of people boasting about deep coins with detectors that are not known for depth.. If you looking for deep coins better to have a detector that will reach down there and get them instead of depending on the halo effect.
Exactly.

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Old 12-19-2017, 11:00 AM
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Originally Posted by calabash digger View post
No I didn't say it NEVER happened... look at what I wrote I said if all the stars lined up just right it MIGHT happen. All I was saying is I hunt old sites where the halo would be present on deep coins. I have dug deep coins on these sites but NONE deeper than my machine will air test. Others have had the same results as you see in their post. I know there are deeper coins on some of these sites because we have dug king George coppers out of the pits.. I also dig copper relics all the time and a lot are very deep but NONE past what my machine will test on it. My hunting partners been doing this 30 years and I have never heard him tell of some super deep coins that were well beyond his machines depth capabilities. I would imagine hes dug hundreds of coppers and Spanish silvers combined. All I'm getting at is its NOT the norm ,if it was I would have seen it and he would have too, and the other guys above would too. FOR EXAMPLE The DANGER is some who believe this are running around with a 5 x8 on their at series detectors and thinking its seeing 12 inch silver quarters and dimes on a regular basis and its not..... and other detectors that don't have depth are not either....AGAIN when some certain phenomenon happens or it MIGHT happen, but this belief that its a regular occurrence and a detector that wont air test over 8 inchs on a silver dime is seeing them at 10 inchs on a regular basis is bogus IMO.. They can write all the articles they want but I'm in the sites where the age is there for the HALO to be present and down here in Calabash the halo hasn't showed up yet and in 30 years of my partner detecting I would think he would have seen it 1 time at least on a old coin.. We can all agree to disagree and like I said above if you want to find deep coins then buy a machine that has some depth to it because if your waiting on the halo to help you out you might just get your feelings hurt.
I know wet soil increases depth detection and multiple coins together seems to help also(I think).

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Old 12-19-2017, 12:42 PM
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Someone maybe talked about their FBS detectors not air testing well and yet they find the deepest high conductor coins with them, far past the air test numbers. My V3i on the other hand air tests coins past 10 inches but the V3i just ain't near as deep as the Etrac/Explorer, yet the V seriously air tests farther than my Whites. Go figure.

One item I have a talent to detect deep, 10 inches easily, are crushed screw bottle caps. Even my Whites M-Series detector(M6) grabs deep smashed screw caps DEEP. I don't believe I have found a 10" coin with anything besides FBS, except in particular soil conditions, i.e very sand based.
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Old 12-19-2017, 04:08 PM
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I really don't have any experience air testing fbs machines so my post was about single freq vlf machine. I do find that my machine hits deeper in wet soil too.

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Old 12-19-2017, 08:29 PM
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I have dug some insanely deep coins at wet salt beaches, far deeper than my CTX will air-test them at. All of them were corroded and the sand all around them was heavily discolored so I believe the halo effect made the difference.

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  #20  
Old 12-19-2017, 09:44 PM
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I think that has to do with how fbs behaves in ground and not so much the halo but I might be wrong.. My deus air test at 12 to 14 inchs on some non ferrous coin sized targets ... if the halo theory is true why am I not digging 18 inch non ferrous coin sized targets on these ancient sites??? We have dug thousands upon thousands of non ferrous targets off these sites ... but non past air test capabilities. All I'm saying is on these old site I have never dug a target past what my detector will air test on and some of these sites date back to the early 1700s... It might happen but imo its not the norm.. BTW the deepest coin sized target ive ever dug was 13 inchs in the ground. It was a small oval colonial buckle..

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