I split most of my time metal detecting with two different detectors and with both I use patterns that discriminate out most of the iron. As a result there is a constant nulling going on, usually just a quick blip, blip, blip. Can all that constant nulling be small pieces of iron or is there a chance that some of the nulling is being caused by small concentrations of minerals in the soil itself? I just find it kind of hard to believe that there can possibly be that many pieces of small iron in the ground no matter where I hunt.
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Nulling:
- Thread starter Mtnmn
- Start date
MNCoinhunter
Active member
Most people would be shocked at the amount of man-made objects that are buried everywhere. I know a couple of spots that are almost impossible to detect.
This is a subjective question, based on the type site your hunting, what you consider a "null", what machine you're using, etc...
gunnar and mcDave are right: there is theoretically spots which are so iron ridden, that when nix out iron, and iron is a "null" on your machine that ..... yes ... areas can be a constant null. Some ghost town sites, ruins sites, etc... might be this iron-ridden. You can test the theory by going all metal, digging everything in a central location, to "see what's there". Dig enough stuff by criss-crossing all-metal vs iron disc, and ....... after awhile, you'll have a mental picture of what the chorus of sounds you are hearing is. There's no easy fix to the school of hard knocks, afterall
gunnar and mcDave are right: there is theoretically spots which are so iron ridden, that when nix out iron, and iron is a "null" on your machine that ..... yes ... areas can be a constant null. Some ghost town sites, ruins sites, etc... might be this iron-ridden. You can test the theory by going all metal, digging everything in a central location, to "see what's there". Dig enough stuff by criss-crossing all-metal vs iron disc, and ....... after awhile, you'll have a mental picture of what the chorus of sounds you are hearing is. There's no easy fix to the school of hard knocks, afterall
Critterhunter
New member
Any machine discriminating out iron will "null" on even a silver coin once it reaches a certain point in depth. Reason being? The microscopic iron in the coil reaches a point where it is now stronger than the weak coin signal past a certain depth. At the very last fringe where a detection field can see the coin it'll drop down to the iron range before it can't even be seen as that anymore.
Also, a super deep coin can also null due to mineralization for the same reasons as iron. It reaches a point at depth where it now is regarded as part of the ground signal and it might not "null" as being iron, but it will null the threshold as a fast change in ground matrix.
Far as iron rejection, I used to be a believer that using no iron rejection was the only way to improve unmasking. I no longer believe that, after seeing/comparing a sharp DD line (12x10) using high built in iron rejection on a machine to one using very minimal iron rejection and seeing the same unmasking ability. Not saying either way is better to unmask, just saying I now believe there is more than one way to skin a cat.
Reason being that lower iron rejection isn't "seeing" a coin at the same time as iron better, but rather it's reducing recover time between "reject mode" of the iron and "accept mode" of the coin right up against it. If a detection field sees iron first, no way to see a deeper coin for the most part. Just the nature of detection fields. First target seen, even off to the side but still in the field, is the one that gets reported, with minor exceptions.
So if the reject/accept mode "lag" thing by reducing iron rejection is what is really going on, then how is there another way towards the same goal of unmasking? The other being that if you use a sharper DD line, you've more cleanly defined when you are seeing the iron, to not seeing it, and then to seeing the coin as the coil moves on. It's more cleanly transistioned, like turning a page on a book, so in effect you've increased the time between "reject" and "accept" in a way, just like lower iron rejection will do.
That's MO anyway and I'm sure others differ. Believe me, a few short years ago I thought otherwise, so I don't blame people for thinking otherwise as well by their experience if they don't agree. I can only go by what I've seen with my own eyes and ears on undug stuff in the field. I don't argue one is more important than the other, only that there are several paths to the same goal...
PS- Depending on the iron/mineral content, even shallow targets can null out. I've seen at one very bad beach that discrimination mode is nulling on coins at only 5 or 6" beach, while all metal pin point mode is easily banging on them hard much deeper. All metal has it's purpose and benefits for sure in some situations. The thing to keep in mind though is it's not seeing a coin through iron any better than discriminate. The laws that govern detection fields still apply- First target seen in the field and it's game over on seeing something deeper for the most part. Where I feel all metal can "unmask" better is the ability to sound off to stuff that the ground matrix is "masking. Not masking by iron like nails or such, but microscopic iron playing havok with the discrimination circuit and choking out targets due to that microscopic iron or other mineralization. I've seen even the best of VLF machines get the depth of a cheap radio shack detector in a bad matrix. That's were all metal or an all metal pin point mode can really shine.
Also, a super deep coin can also null due to mineralization for the same reasons as iron. It reaches a point at depth where it now is regarded as part of the ground signal and it might not "null" as being iron, but it will null the threshold as a fast change in ground matrix.
Far as iron rejection, I used to be a believer that using no iron rejection was the only way to improve unmasking. I no longer believe that, after seeing/comparing a sharp DD line (12x10) using high built in iron rejection on a machine to one using very minimal iron rejection and seeing the same unmasking ability. Not saying either way is better to unmask, just saying I now believe there is more than one way to skin a cat.
Reason being that lower iron rejection isn't "seeing" a coin at the same time as iron better, but rather it's reducing recover time between "reject mode" of the iron and "accept mode" of the coin right up against it. If a detection field sees iron first, no way to see a deeper coin for the most part. Just the nature of detection fields. First target seen, even off to the side but still in the field, is the one that gets reported, with minor exceptions.
So if the reject/accept mode "lag" thing by reducing iron rejection is what is really going on, then how is there another way towards the same goal of unmasking? The other being that if you use a sharper DD line, you've more cleanly defined when you are seeing the iron, to not seeing it, and then to seeing the coin as the coil moves on. It's more cleanly transistioned, like turning a page on a book, so in effect you've increased the time between "reject" and "accept" in a way, just like lower iron rejection will do.
That's MO anyway and I'm sure others differ. Believe me, a few short years ago I thought otherwise, so I don't blame people for thinking otherwise as well by their experience if they don't agree. I can only go by what I've seen with my own eyes and ears on undug stuff in the field. I don't argue one is more important than the other, only that there are several paths to the same goal...
PS- Depending on the iron/mineral content, even shallow targets can null out. I've seen at one very bad beach that discrimination mode is nulling on coins at only 5 or 6" beach, while all metal pin point mode is easily banging on them hard much deeper. All metal has it's purpose and benefits for sure in some situations. The thing to keep in mind though is it's not seeing a coin through iron any better than discriminate. The laws that govern detection fields still apply- First target seen in the field and it's game over on seeing something deeper for the most part. Where I feel all metal can "unmask" better is the ability to sound off to stuff that the ground matrix is "masking. Not masking by iron like nails or such, but microscopic iron playing havok with the discrimination circuit and choking out targets due to that microscopic iron or other mineralization. I've seen even the best of VLF machines get the depth of a cheap radio shack detector in a bad matrix. That's were all metal or an all metal pin point mode can really shine.
bootyhoundpa
Well-known member
switch over to all metal for 5 or ten minutes and dig those nulls just to satisfy your own curiosity...... the more nulling you are encountering -the more good targets you could be missing due to masking... smaller coil and or lower sensetivity setting may help .......
One way I try to get pass as much masking as possible is by hitting the area I'm searching from several different directions. That way if trash masks a good target from one direction, often you can hit the good target first when coming from in from another angle. I've found out by the time you come in at a "45" there are usually very few good targets left to be found. Another trick I use to help clean out an area is to hit it first with the VLF XT-70 and then go back over the same area with the FBS Safari or vice-versa, it seems like what one misses the other picks up on...