I have been suffering from plantar fasciitis and torn ligaments in my left ankle for about 6 months. The plantar fasciitis has cleared up on its own. The torn ligaments have not yet healed so hunting with a dig it all approach just hasn't been possible since last March. Walking is iffy enough, but lots of getting up and down is very painful. So, I have had to limit myself to shorter outings and lots of cherry picking.
I tried an experiment using the F2 iron bias feature during my recovery for some of the parks I hunt that have high iron mineralization. I used Park 1 and Park 2 with F2=4 and just concentrated on obvious no brainer signals. Deep or shallow didn't concern me, just the quality of the response. I hunted with both zero discrimination and with half of the iron range rejected = -9 to -6. My target recovery of deeper low to mid conductive targets pretty much ceased to exist during this time.......deeper silver jewelry and coins along with any depth of higher conductive US modern coins (wheats, copper memorials, clad dimes and quarters, Kennedy halves and modern "gold" President and Sacajawea dollars) was seemingly not effected.
Today, I hunted an exact area that I had hunted a month ago with those settings except that I hunted with F2=0 and dug every target that sounded good. I had already cleared out the higher conductive clad so none was found. I tested every low to mid conductor target from +6 to +22 (the gold and small silver jewelry range) that sounded decent using F2=0, and then switched to F2=4 and F2=9 before I dug the targets. All of these targets which were clear and obvious targets using F2=0 were beyond the range of my handheld FTP Tek Point pinpointer that was set on maximum which usually reaches coin sized targets down to 3.5 to 4" in this park. All of the targets in the photo except for the first two modern pull-tabs (bright silver and red surface finds) were recovered at deeper than 4". Some were as much as 8". They all sounded very good with repeatable signals in all four swing directions (+), and had dig me gold range numbers using F2=0. Using F2=4, all of these targets were iffy at best and the deeper ones sounded mostly like iron. Using F2=9, all of these targets were mostly iron with just a hint of low to mid conductor tones and corresponding numbers.
It is no wonder that I previously walked right over these targets since I had limited myself to digging only excellent sounding targets due to my injury. Even if I wasn't injured, I am not sure that I would have dug these using F2=4. No way using F2=9.
Two of the nickels are fairly old for the Denver area, a 1949 and a 1960. Both were 8" deep and sounded very good using F2=0. The big stainless steel ring (+8) and the Avon gold plated junker (+14) were 6" deep and sounded fantastic with F2=0. The two .925 small silver jewelry items (+22) sounded great using F2=0 and were 5" deep.
So, in higher iron mineralization, are my results an outlier or is using F2 iron bias above zero just too agressive on low and mid conductor non-ferrous targets? Comments, disagreements and Pooh Poohing are welcome.