Depth Vs Sensitivity: The View From My Foxhole

[ColonelDan]

On any evaluation I’ve ever read of a given detector or a head to head comparison, the discussion invariably reverts to the subject of raw detectable depth—it seems the “holy grail” of evaluating a detectors worth can be answered with these two questions. “How deep is detector A? Is it deeper than detector B?”

 

Many years ago, I convinced myself that sensitivity and reactivity were far more important to me than raw depth. I zeroed in on sensitivity and reactivity as it relates to separation and identification at various depths and under various soil/sand conditions. Given that, all the depth testing I ever did focused on sensitivity at a given depth rather than raw detectable depth under a variety of conditions we find in the field. Why?

 

Detectable depth is affected/impacted/determined by many more external factors than just the sophistication of the detector’s internal technology alone. Such factors as soil/sand composition, moisture and mineralization levels, the target’s metallurgical composition, orientation in the soil/sand and level of degradation/condition and even the overall amount of EMI in the area.

 

Granted, sensitivity can also be affected by these same factors and hamper any detectors ability to properly and consistently detect and identify the target. However, I’m more impressed by a detector that can accurately identify a target or separate it from junk at a given depth than one which can merely “see” the target at that same or similar depth but can’t identify or separate it from the junk.

 

While I’m not summarily discounting detectable depth as a desirable capability in a detector, I value its degree of sensitivity more so which enables it to accurately identify and separate the target from that ever present trash. However, as I always say, that’s just me and the view from my foxhole. Your preferences may very well differ.

[CPT_GhostLight]

All good points, ColonelDan. Other factors that can affect depth and sensitivity are coil size & shape, program settings, swing style & speed, and a myriad of other things, including the user's frame of mind. All those things combined create the real level of depth and sensitivity that can be expected at a given time, location, and condition.

I think the quest for the deepest detector is directly related to the increase in competition in the field these days. Many places have simply been picked over from surface to 12 inches down leaving only deeper good targets. With the restricted digging law in my local parks that means no plugs, so deep digging is a no go anyway. If I opened up a 12" hole, the parks department would be on me like a chicken on a Junebug!

Now, on the beach it's a different story. I was at the Treasure Coast in early Spring somewhere between the second and third renourishment projects and it seemed like all targets were really deep except surface trash. I pulled a 2012 penny from 14 inches down, so I could have really used a detector that could hit targets at 4 feet down or deeper. 😁

Of course there's the question of practicality. If you could hit a target at 4 feet down on land or sand, would you dig it, and if so, how many 4 foot holes can you dig in a day?

For me, it all goes back to the Colonel's observation that accurate target ID is more important than shear depth. A detector that gives you consistantly good target information is going to be more valuable than one that just pings anything deep, IMHO.

That's just how it is in my detecting world, but if I go back to the beach, I'm taking ground penetrating radar and a backhoe! 🤣

[nickelNdimed]

I’m sure my Seahunter PI is deeper than my other detectors. I don’t take it to the park. 

On my Simplex, this coil is my latest obsession…. I’ll probably never use the stock 11” round coil on it even though it should be deeper than the 18x4 Arrow. But the Arrow is deep beyond the limits of Simplex target ID stability and way more efficient in coverage and separation in trashy parks or even the beach when covering large areas for recent drops.  

If I want more depth at an older site and better ID capability at depth, I’ll use my Equinox and it’s 11” round or the 6” if I have the patience.

If I want raw depth at the beach or less trashy wet areas, I’ll use my Seahunter (plus it likely won’t leak).

[Guest Dug]

9 hours ago, ColonelDan said:

On any evaluation I’ve ever read of a given detector or a head to head comparison, the discussion invariably reverts to the subject of raw detectable depth—it seems the “holy grail” of evaluating a detectors worth can be answered with these two questions. “How deep is detector A? Is it deeper than detector B?”

 

Many years ago, I convinced myself that sensitivity and reactivity were far more important to me than raw depth. I zeroed in on sensitivity and reactivity as it relates to separation and identification at various depths and under various soil/sand conditions. Given that, all the depth testing I ever did focused on sensitivity at a given depth rather than raw detectable depth under a variety of conditions we find in the field. Why?

 

Detectable depth is affected/impacted/determined by many more external factors than just the sophistication of the detector’s internal technology alone. Such factors as soil/sand composition, moisture and mineralization levels, the target’s metallurgical composition, orientation in the soil/sand and level of degradation/condition and even the overall amount of EMI in the area.

 

Granted, sensitivity can also be affected by these same factors and hamper any detectors ability to properly and consistently detect and identify the target. However, I’m more impressed by a detector that can accurately identify a target or separate it from junk at a given depth than one which can merely “see” the target at that same or similar depth but can’t identify or separate it from the junk.

 

While I’m not summarily discounting detectable depth as a desirable capability in a detector, I value its degree of sensitivity more so which enables it to accurately identify and separate the target from that ever present trash. However, as I always say, that’s just me and the view from my foxhole. Your preferences may very well differ.

 Very well said.  👍👍

[Joe Beechnut OBN]

Beach and water only here...Since all of us have different needs at the beach, your going to see many different opinions of what is important to find treasures.

For me... my hunting depends on knowing what my machines are capable of (And the competitions) ..... which raw depth is the most important. One reason I bought the Fisher AQ (PI) and I modify a few things my Excaliburs to squeeze every last inch of depth I can get from it in all metal. Got to keep up with the D2's..😊

 

 

 

 

[Rick N. MI]

That's impressive for the Excalibur.

I know the the Equinox 800 w/11" coil and Xp Orx w/9" hf coil will hit hard on a 3.77 gram 14k gold ring at 14" easily in a mild sandy beach at a lake. I haven't tried deeper.

Unfortunately I don't get a lot of gold jewelry in the northern MI lakes like you do on the ocean.

[Joe Beechnut OBN]

39 minutes ago, Rick N. MI said:

That's impressive for the Excalibur.

I know the the Equinox 800 w/11" coil and Xp Orx w/9" hf coil will hit hard on a 3.77 gram 14k gold ring at 14" easily in a mild sandy beach at a lake. I haven't tried deeper.

Unfortunately I don't get a lot of gold jewelry in the northern MI lakes like you do on the ocean.

 

14 inches is very good. I'm not sure if my excalibur could hit one that small, that deep. Seems the smaller the gold the more it struggles.

Yes, I can only imagine the water really never gets warm there but for a few months. Short season .

[Rick N. MI]

You got that right. The lakes by me right now are 56F. Warmer in shallow water. I haven't went in the water yet. No big cities where I live. That's an advantage for me. Not much jewelry though. 

[phrunt]

On 6/3/2022 at 4:27 AM, CPT_GhostLight said:

For me, it all goes back to the Colonel's observation that accurate target ID is more important than shear depth. A detector that gives you consistantly good target information is going to be more valuable than one that just pings anything deep, IMHO.

 

This is 1,000,000% correct for me, My Teknetics T2 is probably as deep as my CTX, only it tells me all deep targets are iron or are so wild on the ID's they seem like junk, my CTX and to a slightly lesser extent my Equinox tells me if those deep targets are good, almost to the point its unbelievable by comparison to every other detector I've tried, depth means nothing to me if the ID's are so far off they're useless.  If I wanted depth with no decent discrimination and no target identification I'd wander down to my coin spots with my GPX 5000 and it makes the VLF's seem like a toy when it comes to depth.  I don't want to dig a million holes in public areas so having accurate identification is a must anywhere other than a beach or an farm field which in NZ is pointless hunting as we have no history.  This is why I found the Simplex useless, yes it has good depth if you want to dig everything but it's ID's drop off at very shallow depths by comparison to the Nox or Vanquish or even the Gold Bug Pro or Ace 300i, they all do far better on deep targets than the Simple Simplex.

Around here if a coins been there for a while it's very deep so depth and identification mean a huge amount to me, we have soft soil, if we get a lot of rain and you walk on the grass you leave a dent about an inch deep with every foot step in winter 🙂 It's even worse further towards the coast, I had to dig deep holes to put fence posts in at my place down there, they took about a two minutes each to dig 20 inch holes.  At my other place in the dyer part of the country inland and at a higher altitude I had to dig holes for posts and it took me about 30 minutes a hole with the same depth with the ground being far harder at a similar time of year.

So far for my purpose of deep silver coins in public places the CTX is superior to any other detector I've tried as it's very deep and has great target identification.  I really hope Minelab make another CTX type detector and don't discontinue the FBS 2 technology in favour of Multi-IQ, both are good and both have their strong points but they're very different to each other and one has benefits the other does not.

A little plug for the Detech Arrow too, for an area with fresh drops after an outdoor concert or something it's an awesome coil, it's a shame it's limited to primitive detectors but still, well worth having in the tool kit.