I am concerned about the whole issue of focus, or rather the manifestation now of AF Fine tuning. I wonder if in fact and I do not include those who have sent cameras back to Nikon, if many focus issues are down to other factors e.g. appropriate shutter speeds in many cases and matching the correct apertures in others.
My experience is varied, but beware. I have conducted extensive tests with LensAlign and associated FocusTune. I saw some extremely varied results with the same lenses in particular the 24-70mm f2.8. I went through these exercises not because I had any focus worries, but because I was interested. Some results worried me greatly, however there is good news for me anyway.
I have concluded that any fine tune testing must be conducted under the most rigorous conditions, almost laboratory in nature. If not the results will vary greatly and some will result in what I now call "Fine Tune paranoia or FTP".
I had no worries about my lenses on my D800 or D7000 and in the end I actually scrapped all the results and went to a flat target in perfect light and tested at various focal lengths. I am left with the following conclusions where the use of angled targets are concerned:
1. AF fine tune is best conducted on Prime lenses, if required at all.
2. If fine tune is to be attempted on a zoom lens then choose the focal length usually used. I have little faith in this method as that's like saying I have bought a zoom, but to use as a prime.
3. If attempting fine tune on any other focal point other than centre focus, beware the results as it may well screw up other points.
4. Finally, certain parameters must be obeyed, lens orientation to target, available light, reduce shake by using Mup and remote release. If these are not accomplished the whole exercise will be a waste of effort and shutter activations.
This is my take on AF fine tune, my LensAlign now resides in the cupboard until I really feel I have a problem with a lens and then only if it is a prime lens.
This is my take on it, but others will have many varying ideas I'm sure. There is certainly much to be applauded when assessing prime lenses via angled target methods provided conditions are perfect. All I can say is that all my lenses are now set to zero fine tune and in place I have refined my shutter speed to aperture techniques with much success.