Coil Size & Unmasking Does It Matter?

Unmasking and coil size is something that's always interested me, it's clear that the overall viewpoint is the smaller the coil the better it is at unmasking. Something about this theory never sat quite right with me,  surely if you use a small coil then the iron would appear much larger to the machine. I hear the term "you can get in-between the iron", there's part of me that sort of understands that because the smaller the coil the less surface area is communicating with the ground. This means 'in theory' that you're not going to get as many targets under the coil all at once, so if you have sporadic iron with nonferrous targets in close proximity there's potentially more chance of hitting that target without a load of iron being under the coil at the same time. However there's part of me that feels the "small coil" theory is just another misconception that's been made real through years of "metal detecting whispers". 

The aspect we must not forget here, in the mainstream, all metal detector coils are double D and due to this configuration they're limited within their ability to see masked targets. This coil design alone can put you at a disadvantage on iron contaminated ground, it doesn't matter what settings you have on your machine or how high your recovery setting is. The simple fact is, one coil can't do it all, that might come as a surprise to some but the importance of the coil still doesn't quite hit home with to many people out there. 

To try and bypass this issue, if I'm swinging a double D coil I'll focus on small areas at a time and then go over the same ground from as many different angles as possible. I use this method a lot on the River Thames foreshore when I'm swinging the Legend with the 6' inch coil. Also if I get a clean tone from one direction, which fades as I rotate then I'll dig this target. On the Thames target masking is near insanity and you have to throw all the preconceived ideas you have on how masked targets sound and respond. 

So leaving concentric coils out of the equation for the time being, and taking into account the limitations of the double D configuration coils. Does coil size really matter when it comes to unmasking targets in close proximity to iron. This is a question that I find really interesting, below is a video of me using the Nexus MP V3 with the 20' inch low frequency Double D coil unmasking a coin in close proximity to iron. I personally think it does a really good job and makes me think that coil size isn't so crucial when it comes to unmasking and separation. I'd actually be interested to try some larger coils wound to the higher frequencies, I think the results could be surprising.