Jerry, I think there's a possibility you don't realise that the camera has internal, non-volatile, memory which is entirely separate from the memory card(s). The Fine-Tune data is stored in that internal memory, NOT on the memory card(s).
>one limit to this... the D7100 can store AF vales for up to >12 lens types. Only one value can be stored for each type of >lens. > >I am assuming that type means model and not prime, zoom, >telephoto or wide angle. I believe type to be a bad choice of >words.
Yes it means model. However if the lens can accept Nikon's AFS TC's, you can save a separate listing for the bare lens and each of the TC's even with different fine tune values. I don't know if it recognizes Kenkos latest Pro TC's.