Disc to mode testing on the F75Ltd.

[WV62]

Decided I would run the new F75Ltd through some testing to try and see where the extra depth comes in at as the disc is turned up.

So I started by doing a factory reset which put the disc at 15 and in the dE mode and the 11

 

[Steve O]

Nice and surprising chart Ron.

 

[sprchng]

It would be interesting to see your GB number and also what the results were with a notch put in to accept say 20 to 35 for low conductors after a disc setting of 65.

 

[MarkCZ]

It would be interesting to see your GB number and also what the results were with a notch put in to accept say 20 to 35 for low conductors after a disc setting of 65.

Well ground balance numbers during air test doesn't have much effect, air is the most perfect medium we have here on earth to transmit a signal through and can't be balanced out.
I'm thinking that Ron stated a factory "Reset" and then noted his setting changes with no mention of a change in ground balance that it was most likely at a factory preset.

Mark

 

[WV62]

Mark is correct, I did the factory reset and I just checked and that would put the GB at 90.

I will have to set back up and do something with that notch request.

Ron in WV

 

[Elton]

I have done that with T2 but never tried hunting in 90 with F75 LTD..

On the T2 it worked better in high trash areas not using the GB.... just leaving at preset..

 

[WV62]

Elton, I am not suggesting to hunting with the GB at 90, when I do the factory reset that is where it resets to 90. For air testing it really don't make any difference where the ground balance is set. The main for testing the disc to mode is keep everything the same, if I was to change the GB manually to say what my ground is 57 I could do the same testing and may get new set of numbers or they could be the same.

I was just trying to see what if any the disc settings affects the different modes of operation. If you notice the spread sheet shows the dE mode has a gain in depth with higher disc settings, and the JE mode looses depth with higher disc settings, while others don't seem to be affected at all by any disc changes.

I will be testing that notch request, and run some trash items here in a little bit. If somebody wanted to throw out a GB number I could try that and see if I get different numbers.

Ron in WV

 

[Elton]

All I was saying manual says you may not have to GB in Disc mode... I have never tried that with detecting or air testing to be honest..

 

[WV62]

Here is the latest round of testing, I didn't get any takers on giving me new GB number so I picked 60. I also included the notch request and I did get some different numbers. I also made a correction to the original numbers for JE at disc 65 it was 10" and I corrected it to 7" noted in red.

Ron in WV

 

[SteveP(NH)]

Depth results when air testing are usually not a reliable indicator of what you will get in real use.

The reason is that the real test of a detector is how well it can pick up the faint target signal at depth in comparison with the much, much stronger ground signal it is getting from the dirt. Ground balancing is a way to adjust the detector performance for the specific dirt it is detecting in. Ground balance numbers are meaningless when air testing as the air doesn't have any response to adjust against.

Think of it this way, suppose you wanted to test a car to see how fast it can go. Air testing is like jacking the drive wheels up off of the ground, setting the parking brake and seeing how fast the engine can spin the drive wheels when they aren't touching the ground. That sort of a test, doesn't say anything about how the suspension is able to handle curves or bumps in the road, how responsive the steering is, how the engine power is able to work against friction, etc. Air testing a detector is the same thing, it doesn't test how able to detector is able to pick out the tiny target signal from the overwhelming ground signal. Most of the different modes in the F75 are designed to adjust the machine's performance for different types of targets (small, low conductor in one larger high conductors in another, etc) in different soil conditions for example plowed field (PF) is for loosely compacted soil with air pockets in it, DE is for normal ground and so on. Air testing with the same target isn't a valid way test different modes as it doesn't provide the soil conditions that the modes were designed to operate in.

Air testing has some uses such as learning how the machine responds to different types of targets but measuring depth performance isn't not one of things air tests are good at. In fact Dave has said before that a detector manufacturer can setup a machine to perform fantastic on an air test and the expense of reducing its performance in the dirt (at least if I understood him correctly).

 

[MarkCZ]

Depth results when air testing are usually not a reliable indicator of what you will get in real use.

The reason is that the real test of a detector is how well it can pick up the faint target signal at depth in comparison with the much, much stronger ground signal it is getting from the dirt. Ground balancing is a way to adjust the detector performance for the specific dirt it is detecting in. Ground balance numbers are meaningless when air testing as the air doesn't have any response to adjust against.

Think of it this way, suppose you wanted to test a car to see how fast it can go. Air testing is like jacking the drive wheels up off of the ground, setting the parking brake and seeing how fast the engine can spin the drive wheels when they aren't touching the ground. That sort of a test, doesn't say anything about how the suspension is able to handle curves or bumps in the road, how responsive the steering is, how the engine power is able to work against friction, etc. Air testing a detector is the same thing, it doesn't test how able to detector is able to pick out the tiny target signal from the overwhelming ground signal. Most of the different modes in the F75 are designed to adjust the machine's performance for different types of targets (small, low conductor in one larger high conductors in another, etc) in different soil conditions for example plowed field (PF) is for loosely compacted soil with air pockets in it, DE is for normal ground and so on. Air testing with the same target isn't a valid way test different modes as it doesn't provide the soil conditions that the modes were designed to operate in.

Air testing has some uses such as learning how the machine responds to different types of targets but measuring depth performance isn't not one of things air tests are good at. In fact Dave has said before that a detector manufacturer can setup a machine to perform fantastic on an air test and the expense of reducing its performance in the dirt (at least if I understood him correctly).

You are correct in that 11" of air is not 11" of earth (dirt), I think that's pretty much understood, but 6" of air isn't going to make 11" of earth either.

Earth (dirt) for the most part has minerals in it, to a detector this is somewhat like a fog, so there is always some loss in the transfer of the signal (average soil). There isn't anything about mineralized soil that would increase the depth other than target halo and that's mainly Iron targets.

So, if I take a giving detector that will only air test a US quarter out to 5" (I've had this happen) there isn't any use taking that detector to a place to coin hunt where I know the silver coins reside at the 6" to 8" range. On the other hand if a given detector can air test the same quarter out to lets say 10" then its still not guaranteed to reach the 8" coins, but it stands to reason that its got a better chance and one that will air test to 11" has a little better chance.

Air, test tells another story, it lets the user know what the detector is trying to do, in other words, it will perform its best in air test, most depth (except for halo) best discrimination, if its poor in air test then its not likely to be better in the dirt.

Mark

 

[MarkCZ]

In Ron's test what's seems to be hard for some of us to get our minds rapped around is the F75 in some modes as you increase the discrimination the sensitivity to depth may increase. But the test also confirms the information in the F75 manual.

The F75 discrimination system is much improved over conventional discrimination systems,
and may function quite differently than other discriminators you may be accustomed to. In
older systems, the apparent sensitivity decreases as discrimination level increases. The F75

 

[Elton]

n/t

 

[sprchng]

For whatever reason , I thought your first test was in a test garden of some type , hence the GB number question. I agree it's immaterial in air testing , which has limited usefulness ,but your second set of numbers is very interesting. It appears notching back in from max disc may be an interesting alternative and allow the inclusion of low conductors. My ground frequently GBs above 88 and an 8" deep quarter is undetectable with quiet "sensitivity" settings. This could add some interest to the game thanks for the test WV62

 

[WV62]

Cut and paste from my original post to start this thread.
Keep in mind I was not trying to get a max depth, so the setting changes that were made were the disc and the mode change and let the numbers fall where they may.

I guess by me using depth numbers some would assume that I was trying to come up with one mode over the other for hunting. But for this test all I was trying to show is how disc settings affect each mode or processor. As I said in my opening post I was not trying to come up with a max depth for any one mode of operation, if I was trying to do that I would have change other settings like sensitivity which was at 60 for all the testing. Now I only used one target because any more targets or other settings would not tell me what I wanted know.

I know air testing is not going to be accepted by everybody, but for comparison it seems to work fine for me. For example my brother MarkCZ and I have had the same detectors like Fisher 1270's. When he got his, one of the first things we did was rig them the same, set them the same and air test them. Now that didn't tell us how deep they would detect a coin in the ground but being they gave close to the same air depth readings on our target that we felt neither of us had a bad detector.

Now for the results I was trying to show in my testing.

DE mode does gain depth with higher disc settings
BP mode is not affected by disc setting changes
JE mode looses depth with higher disc settings
BC mode is not affected by disc setting changes
PF mode does gain depth with higher disc settings
CL mode is not affected by disc setting changes
My thought was with this kind of knowledge if you were to chose to hunt in one of these modes it may help to know what will happen if you start adjusting your disc control.

Now with the adding of notch in of 20 to 35 with a disc setting of 65 it did add a little more depth.
Now with GB change from 90 to 60 it did change some depth numbers.

Now we still don't know how deep the F75 will detect a silver quarter in the ground. I have found coins down to about 8" here in WV, I just don't see that my in ground testing real world depth findings does anybody any good unless you are hunting the same ground I am.

Ron in WV

 

[MarkCZ]

I think I got it!!

Air Test is the use of a universal medium "Air" I may get 8" in my ground, but somebody in Main might get 12" So, if I read some test from the guy in Main digging dimes and pennies at 12" using the exact same setup I have but I'm getting a dime at 8" is my detector broken? or is it the difference in the "Medium" So, how can two people thousands of miles apart give some useful comparisons?
We can't use our soil, its to different?
Air! set to the same settings the units should fair about the same, or close anyway.

The depth numbers in your test really just show how much the discrimination effects the different modes and even it being air test it shows what the electronics is trying to do while actually detecting with it (actual results may very)

I believe in the past there was a certain High Tech guy doing super tunes on certain detectors and in the final test of how good the unit came out he sent it back to the owner with a report of what he done and how much of an increase there was in "Air Test On A US Dime" and if you had one that didn't make that grade then in his closing statement he would advise you that you may consider trading it off!!

There isn't anything about "Dirt" that makes a detector work better! (okay, halo, a hubcap two feet under the coin) they're countless reports of people digging high tone tabs out of the ground, but they air test them and there low tone and they want to know why? because the air test is the PERFECT environment and the ground isn't. Fluke things happen, call them an "anomaly" outside of that the detector will perform better in air test. So, why use an air test at all? simple, if it can't make a decent grade in an air test and do what's its supposed to do then I know that that score will be less when in the real world, not more. I never expect to take a detector out detecting and it hit on coins at 14" if it only air test to 9" (other than some kind of anomaly) so what I look at in air test and depth is for me to get those 8" coins I need a unit that will at lest air test something more than 8", but what? I'm thinking 10" (or more) would be one to try.

Over the winter one can learn a lot about a detector by doing air test, but just don't get the idea that its going to do the same thing in the dirt, but the test shows you what's it trying to do, then try to factor in the negative effects of the ground (or expect)=
Some what less depth,
Poorer ID numbers, (at depth)
Other nearby trash targets to through things off
and the list goes on and on.

What I don't understand is when somebody post something up trying to show the effects of different settings or mode changes which in turns is showing how the electronics are responding to the changes the whole idea is shot down because its an "Air Test" so now the test has No Real World Merit at all, or does it?
No, Ron's air test at 13" may not get you 13" in your ground, but it wasn't supposed to! what it does show is how the electronics are reacting to the setting changes. So, the numbers are valid in what the were meant to do, responses of the electronics using different setting, not how deep the F75 will hit on coins in the dirt.

Well, I think I got it LoL!

 

[WhatTheBeep]

Air tests are indicative of how deep a detector will perform in any type of soil. The soil type makes a difference in depth, of course. The inert sandy soil in parts of Florida and some other places are very similar to air (and don't even require ground balancing), and the depth at which an object can be detected in the air will be approximately the same depth the same object will be detected in the inert soil. In soils that contain magnetite and other minerals detrimental to metal detecting, the depth at which a certain machine will detect an object in the ground will still be roughly a percentage of the air test, depending on amount and type of mineralization present. It would, of course, take an unreasonable amount of scientific effort to provide a formula for percentage of air test depth for each type of soil we detect in and each type of machine we detect with, but it doesn't matter in the end in this instance because it's relative. If Ron can squeeze maximum depth out of 60 Sens in an air test on his F75LTD with the 11" DD coil with Disc at 65, 20-35 notched in while in CL mode, I can be certain that barring coil, circuitry, or EMI problems I'll get maximum depth out the same version of detector and coil with the same settings in my part of the country. His maximum in-ground depth at those settings might be 10" in West Virginia and mine might be 8" in Texas due to soil type, but I can use his valuable air test data to milk my F75LTD (if I had one, of course) for all it's worth in my ground.

Anyway, great testing, Ron! I'm sorry to say that my F70 doesn't seem to benefit the same from 65 Disc and is missing lots of stuff your F75LTD has, but it's inspiring to see someone thinking outside the box and getting good results from it!

 

[WV62]

Thanks guys, I was beginning to think I was the last of the air testers out there.

For the rule of thumb where I hunt I take off at least 2" to 3" from my air testing numbers for what I will get in the ground.

I air tested all my coils last night to see what I have that I may be able work with and try to get some more silver out of areas that have a lot of trash. I think I will try a real world hunt with the little 6.5" elliptical in CL mode. It was hitting my quarter at 13" and a dime at 10".

Air testing is more interesting than re-runs on TV

Ron in WV

 

[MarkCZ]

Air tests are indicative of how deep a detector will perform in any type of soil. The soil type makes a difference in depth, of course. The inert sandy soil in parts of Florida and some other places are very similar to air (and don't even require ground balancing), and the depth at which an object can be detected in the air will be approximately the same depth the same object will be detected in the inert soil. In soils that contain magnetite and other minerals detrimental to metal detecting, the depth at which a certain machine will detect an object in the ground will still be roughly a percentage of the air test, depending on amount and type of mineralization present. It would, of course, take an unreasonable amount of scientific effort to provide a formula for percentage of air test depth for each type of soil we detect in and each type of machine we detect with, but it doesn't matter in the end in this instance because it's relative. If Ron can squeeze maximum depth out of 60 Sens in an air test on his F75LTD with the 11" DD coil with Disc at 65, 20-35 notched in while in CL mode, I can be certain that barring coil, circuitry, or EMI problems I'll get maximum depth out the same version of detector and coil with the same settings in my part of the country. His maximum in-ground depth at those settings might be 10" in West Virginia and mine might be 8" in Texas due to soil type, but I can use his valuable air test data to milk my F75LTD (if I had one, of course) for all it's worth in my ground.

Anyway, great testing, Ron! I'm sorry to say that my F70 doesn't seem to benefit the same from 65 Disc and is missing lots of stuff your F75LTD has, but it's inspiring to see someone thinking outside the box and getting good results from it!

I agree, keep testing!

But. let me explain Ron's depth numbers are NOT him squeezing MAX depth from a sensitivity setting of 60.
Ron, wasn't looking for anything in the depth numbers as far as usable depth while detecting.

The depth numbers in his test were nothing more than a "Barometer"
A sliding scale to show the effects that the discrimination has on the detector's sensitivity in the different modes. (not max depth)

What his test reflects is the discrimination setting has different effects in different modes!
If the depth numbers would have landed at, 6" 7" or 5" but showed the same effects on discrimination vs sensitivity then Ron would have used those numbers to achieve the same results he was looking for, that's what he meant by saying "Letting The Numbers Fall Where They Fall" He never meant for anyone to really look at his chart for "Depth" but rather to gain some usable information (insight) and possible better use of the discrimination control in the different modes.

So, in the end he wasn't saying,
Hey! Look at how deep I got my F75 at a sensitivity setting of only 60.

Mark

 

[SteveP(NH)]

Mark you missed my main point. Doing comparative depth testing in air isn't going to provide accurate results. The original poster did airtests of different F75 modes and offers them up as an comparison of the relative merits of each mode. My point is that airtesting say plowed field mode in air on a coin isn't valid. My experience is in a freshly plowed corn field you will have better results than using de mode for instance, an airtest won't be able to duplicate those results.