There is no machine that "shows you what's in the ground" before you dig it. Despite any catchy advertising jingles you may hear. Despite any ads you may see, that seem to imply they show shape and/or composition.
The type/brand you refer to, has a big problem , as do all of them that purport to show "shape". Namely, that the pixel sizes are AT BEST, an inch square across. Hence the only "shapes" it would show, is enormous objects, like if you were going to trace out foundations of a building, or the square or rectangle shape of a giant safe or door or something.
For objects that are the size of a coffee can, you will get nothing but a "blotch of messy pixels". You will not get the magical TV image shape of a coffee can. Even an item with a distinct specific shape (like a horse shoe) is nothing but blotch of messy pixels.
The advertising photos seem to imply something different . But in actual field conditions, you will be left with JUST AS MANY GUESSING GAMES, as you would with a standard detector. Ie.: dig it up and look at the durned thing.
And the same applies to advertising that seems to imply they can tell composition . Eg.: gold vs aluminum vs silver vs iron, etc.... There may be ranges on the TID scale that say "gold" or "aluminum" or "silver", etc.... But those are just general categories. Ie.: for a ring or a coin-sized item (size plays into the entire enterprise). And trust me: Many items share the same conductivity ranges. And cross multiple quadrants of ID, just by changing the size.
So here is your best bet , if you're strictly looking for coffee can sized item. And not wanting to be bothered with pesky coin, and tab, and nail sized items: Simply get yourself a 2-box detector. Like a TM-808. It will not see anything smaller than a soda can. Thus it's the perfect discriminator against all small items. It will only see soda can and larger sized objects.
it can not tell you coffee can vs toaster oven vs anvil vs hubcap though. So hopefully your search zone is not littered with commercial/industrial debris. Ie.: hope you're not detecting in a junkyard or dump.
