Thanks David. I have always been very resistant to seriously attempt fine tune, although admit I have tried it. My problem with it, until the Mansurovs article, is that I read many interpretations and methods especially on forums. However most "expert" written books just mentioned it was possible and went no further. For that reason I was always reluctant to mess about with what I didn't have a clear idea of what I was doing.
Than I read my first ByThom book, the D800 manual and he went into much depth and gave me a greater understanding. However, I was still very nervous. Then, Nasim gave us his thoughts and it helped to give me confidence to try it out with LensCal. I only have one lens, a 70-200mm f2.8 which I am worried about, all others gave me no worries at all as all were free of focus problems when pixel peeping. I have sent that lens to the repairers, because it needs a service anyway. I still don't quite understand how one fine tunes a zoom lens across all focal lengths, but will accept that if it's used predominantly at a single focal length that is possible. I use that lens from 70 thru 200mm so that doesn't satisfy me.
Finally, the LensCal is not available in the UK and costs a fortune to import. One kind member wrote to me and asked if I would like to borrow his. As it's only one lens I've politely declined the very generous offer.
I am rambling, but I see AF-fine tune as being a routine to be attempted under almost scientific laboratory standards, even more especially on zooms. However following the article I am now brave enough to try it on my D800 with my primes. So, thank you Mansurovs