Birding Camera

" I am easy to convince all I need is one critically sharp feather detail showing BIF not just a bird that happens to be in the DOF "

I'm afraid you can say the same for the bulk of BIF shots from APS-c and FF shooters Jim, I suspect what you are comparing it with in your mind are the best images that one gets from the real experts with £8k+ worth of kit typically 7D + 500 F4LIS or equivalent and years of experience

There's nowt wrong with that requirement, particularly as, by defintion, no m4/3rd or equivalent cost system can ever match it