http://www.garrett.com/hobbysite/hbby_infinium_main.aspx
I have been using an infinium for several years. In the right environment, it's a killer. I mostly use mine for water hunting, but have had some luck relic and coin hunting with it in the woods. Here's a general description of the infinium LS which I wrote some years back which gives a summary of it.
"The Infinium does have some discrimination characteristics. It's not like an accumulative type or notch found on VLF type detectors. In fact, the Infinium is entirely different then any other type of detector. What the Infinium can do as far as discrimination is concerned, is give a tone HIGH-LOW for iron, aluminum and gold. It also gives off a LOW-HIGH signal for silver, copper and again iron. So iron and other junk is always the wild card in both types of signals, as it is a Pulse Induction type of detector. However, the Infinium also comes with an iron check, which again helps with getting a better probability of what type (iron or not?) target it is. Now the Infinium has a bit of a learning curve, and if you are new to metal detecting and lack basic theory on how the machines operate, don't buy one. It will be a lesson in frustration for you.
Now having said that, other little techniques are on your learning curve to be discovered. For instance, the smoothness/roughness of the tone gives a hint as to whether it is an iron rusted target or not. The "Sustain" length of time that the Infinium gives after reading a target gives you a hint as to its size. The Infinium gives a double bleep on bobby pins and wire. So......if you only want to dig gold, only dig the HIGH-LOW signals. That removes a lot of signals that you can leave in the ground. Also, use the iron check, which even cuts out more targets. If you want to dig mostly coins, including old deep silver, dig only the LOW-HIGH signals. Again....use the iron check.
Is the Infinium the holy grail of detectors? No it isn't. It's a PI and loves iron, like all PI's. Iron can not be discriminated out like a VLF detector. But it goes DEEP! It must be ground balanced and a proper frequency must be picked for maxamum performance. I have pulled rings out at over 14 inches with a nice strong signal. It is one of (if not the) deepest machines available. It was designed to get gold in some of the highest mineralized soils in the world. It works in all salt water/beach environments and is water proof too.
Is it a good coin shooter? Perhaps, but only in areas where there are few targets. It's not practical for park environments, as it picks up all metals, even those that your VLF will miss. I have had some success using it in the woods, digging only the LOW-HIGH signals. It should also perform well at relic hunting too.
Where it worked best for me was in hunted out beaches where most of the targets had been removed. The best beach hunters dig ALL targets. The Infinium isn't for everyone, and is not a do it all detector. But if you give it the time it deserves to learn it properly, and use it in its proper environment, it is a killer. I have my best gold ring year ever in 16 years using this machine."
