But in the "real test bed" conditions can change, some days the weather is hot and the soil dry, on other days it's cold and the soil is wet, maybe the conductivity changes, so how is this good for comparisons? You also don't know if the objects are still in place where you have buried them months or years ago. Earthworms, moles etc. can deepen or bring the metals upwards. In the video it's not comprehensible, how deep the targets really are, so there is also much room for manipulation (this is not an accusation, only in such videos I cannot believe what I can't see)
Jacza, everything you said above is true, their is no disputing that, However, the key word is "Test". In the field though everything changes. In some of the fine video's I've watched on T-Net, such as those by calabash, they can and do give a fella an idea of what he can/cannot expect from any given machine. Such as just how the audio response might be, or just how the VDI's might show, what setting might respond better in a given situation etc. We have all seen the "unpacking" of a detector, conclusion?, yes, they all arrive in a cardboard box. We have all seen "air test", for me, only tells what a detector sounds like in tone and pitch, and what a VDI# might read on any certain target (in the air) if you should see any floating around somewhere. In a video (such as calabash's) and others, comparing different machines in say a controlled test CAN BE very helpful AND informative in strong and weak points between any two, three or even four different detectors, and their have been some "eye openers". I read so much about Depth, Depth, Depth. If ALL you want is depth, then I would guess one would want a PI machine with the largest of coils, but that would be a nightmare in most types of hunting, and I read a lot of VDI accuracy, accuracy, accuracy!, Well again, if that is of most importance, then perhaps detecting over a large asphalt parking lot might be best, coins are flat and "shallow". Many video's can be somewhat annoying, and only show how some just like filming themselves, others though, (such as above) can be really helpful put out by some guys who have been around the block more than a few times with detectors, and is showing what he learns as he is learning it, and just how it just might compare with other well know machines. No such thing as a "Perfect" detector. Perfect for me would be one showing real pictures of what's in the ground, not icons, real pictures, like where you can read the brand of bottle cap, and with the press of a button "suck" the target out of the ground for me. We all have good detectors, and I think we all do pretty well. It's a hobby with us, should not be a competition. calabash's "test bed video?" Better than most I'd say.