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To notch or not to notch, that is the question

leeh

Junior Member
Joined
Jan 31, 2007
Messages
53
Hello everyone, thanks for any advice in advance. I am a newbie trying to select my first detector. I am drawn to White's Prizm line of detectors, specifically the Prizm V. I like this detector because it is mid-range in price, and it has an easy to read display. It has around 8 different icons (nail, foil, penny, etc.) that identify the target. Some targets overlap such as bottlecaps, pull tabs and jewelry. It is my understanding that this is due to the "magnetic frequency" of these alloys, and no detector can discriminate between them. I had planned to use the Prizm's nice notching feature to eliminate nails, bottlecaps, foil, and pulltabs, but I read an interesting field test on the Prizm V last night. It said that sometimes a pull tab would actually turn out to be jewelry. That iron could be gold. I think the same could be said for bottlecaps and foil. As I don't want to overlook jewelry and gold, I'm wondering now if I should hunt in all-metal mode (i'm assuming that means nothing notched out). I think i'm seeing now why the more expensive models cost more. Do they discriminate between a pulltab and jewelry? Any advice would be appreciated.

LeeH
 
iv'e only been at this for 2 years but,, it's my understanding, and from experience that there's really no way to tell the difference,, especially on small gold items,, even gold rings can be tricky.....i would imagine i've missed a gold chain on two also,, because i don't dig every signal i hit, but in the tot-lots especially i'm working on that.. also from what i understand get the best model you can afford..
i'm a true beliver in the mxt myself ...but with the right adjustments, any machine can be your best friend.. :D :D :D :D :D dig,dig,dig..... :D
 
Hi leeh, there isn't a detector made (to my knowledge) that can id items 100%. Detectors with target id gives you an idea of what it thinks it is. It id hard to id some targets that have the same composition and size. Kinda of like trying to id a penny and a dime, they are so close that they can trick the id. ID machines are very nice, but I like my Tesoro Cibola that has no id display, I set the discrimination to just knock out iron, I dig some junk but also get the good stuff. I am sure that some id machines id more accurately than others but none of them are always right. That is what makes this hobby so fun, it is always a surprise. Steve.
I forgot to add -
White's are great detectors, well made,light weight,dead on pinpointing,good battery life,etc. And yes all metal does mean nothing is notched out.
 
Leeh,

The icons are really a gimmick. A whole range of different VDI readings are aglommerated into 1 icon. If you only have an icon to represent that whole range, then it won't be accurate.

It is not "magnetic frequency". It is really the target's conductance, at the frequency the detector operates that the readings are based on. This depends primarily on two properties of the target: the resistivity and the permeability of it. Different combinations of these two quantities can map into the same result (VDI number). That is why many different types of targets can "alias" together and produce the same number.

For example, a US nickel will most frequently read a VDI of 18, with some variability based on the angle (laying flat or angled in the ground), surrounding mineralization,... Some types of pulltabs will come in at VDIs of around 20. So, if the manufacturer takes VDI numbers from say 16 to 22 and map them into an icon, nickels and pull tabs will show under the same icon.
 
Most VDI machines are also inaccurate at depth.
The best way to be is to have the disc set to knock out small nails, dig everything else.
Also remember "low and slow", every inch the coil is above the ground, an inch of depth is lost.
 
This is some good advice Lee. About all the notching or blanking you will want to do is for small iron. The gold ring I found a year ago rang up on the VDI as foil. When you get your machine dig in the all metal mode for a while till you are comfortable with the different sounds the machine makes for the targets you find. Pay close attention to these sounds, keep a mental note as to what they sound like for the things you dig up, and then you will know what is a good target and what isn't.
 
Leeh,

I hunt with a Prizm III equipped with a 9.5" coil. Unless an area is extremely trashy, I hunt in all metal mode and keep a close eye on the icon display. I dig everything...and I mean EVERYTHING....that displays above iron. Too many times I have seen the quick flash of one of the coin icons yet there was no audible signal, or beep sounded. That is an indication of a deeper target (and hopefully older target). The White's Prizm line do not give off a range of sounds like some detectors do. You get either a beep (98% of the time) or this one other tone that is very harsh and unpleasant (like when you pass your detector over a manhole cover--other Prizm owners know what I'm talking about). Anyway, under most conditions when you get a beep, it might be a long beep or a very short beep, but that's all you'll get. The longer beeps are usually larger objects and/or targets that are closer to the surface, while shorter beeps are smaller targets and/or are somewhat deeper.

As mentioned earlier, I hunt in all metal mode, and as a result I dig a lot of trash, but I also have a very high nickel ratio (at least when I compare my penny, nickel, dime, quarter ratios with other detectorists on this forum (approx. 30% of all my coin finds are nickels). I did not always hunt in all metal mode, but once I began, I re-hunted areas I thought I had thoroughly hunted and nickels started popping up all over the place. I had been discriminating them out before!

Good luck with whatever you decide, but the more you dig (even trash) the more good stuff you'll eventually uncover.

Harley-Dog
 
Most of the rings and jewelry I have found have been in the nickle to screwcap range, I discriminate out the iron and dig everything else. Digging iron will quickly discourage you so I would recommend setting it up to detect just above iron. Good luck and happy hunting.
 
I don't know about your detector, but I can tell the difference between a good target and a pull tab by the sound, even though the meter can't tell the difference. And I have a single-tone detector. After a bunch of years using this machine, I know what it is trying to tell me - and rings sound, well, round. I've never used the notch feature at all, since not all tabs read at the same place, and even the same type tab will read differently under different conditions. It's just never been that useful to me. But then, my machine does have a factory preset reject setting which does mute most pull tabs and small iron... but I lose out on the rings that way, too.
 
i only notch iron since i don't relic hunt to often . but beware what you notch unless your hunting with me then i can back over where you hunted and find what you notched out :lol:
 
has anyone tried notching out pennies on their ace 250? the other day i dug 136 of them during an all day dig. when i stop and think that it only adds up to $1.36, i start to question whether it is worth it. after 2 and a half months i have dug almost 1,300 of them. it was fun for a while but my enthusiam for digging pennies is declining fast. :lol:
 
A penny saved (dug up) is a penny earned! (and one penny closer to the detector upgrade!) :yes:
 
My thoughts are some detectors are better at telling good from bad but there is no 100%. Just yesterday I dug a silver ring that read as pulltab on the VDI but it showed ring on the icons. I've found that those icons can be quite useful. I get a target that reads in the pulltab range on the VDI(numbers) but has the ring or nickle icon first and the foil/pulltab second I dig. On the DFX you get 2 icons meant to represent the possible target. Which ever icon is first has a slight better chance. Only on the very deep rings has the icons been totally wrong.

I use 4 sources of input to make my decision to dig. If the numbers on the VDI are good, if the Signigraph bars are good, if the icons are good and most importantly, if the sound is good. If the sound is good I ignore all other input.

In most cases all metal just isn't an option. Well it is, but you'd spend all your time digging a whole lot of junk. If you find a location very low on trash then by all means go all metal. And um... give me a call. Yes there is a reason some detectors cost more.
 
I hunt with an ACE250, which does not use VDI numbers, just icons. I have learned over the last 2 years that using the icons for anything over a 4" deep target is pretty much useless with this detector. Hoser and Texaspast are right on - learning to rely less on the display and more on the differences in the tones is the best thing you can do to improve your "treasure to trash" ratio. I have been hunting with the machine in "All Metal" mode alot the last few months, using the tones rather than the display to tell me what the target might be. If I'm not in an area where relics are a possibility, like a tot-lot, I'll manually notch out the lowest range iron stuff, but that's all the disc I use. I'm at the point where I can easily hear the difference between a nickel and a pulltab. That said, I still dig almost all the pulltabs, because some pulltab tones may still be small gold items. If you want to find gold, you'll have to dig pulltabs and nickels, and lots of them! So if you don't already have them, get a good, comfortable set of headphones, put your machine in All-Metal and prepare to dig a lot while learning those tones. And remember, by hunting in "All METAL", you will also get a little extra depth out of your detector. That extra inch or so could make all the difference in how fast your treasure chest fills up!
 
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