Thank you for your thoughts! I fear that I might be going down a road without a conclusion too. The manual says don't use fine tuning because it causes errors in minimum and infinite focus settings, so it makes me wonder.
I am obsessive compulsive with accuracy. When two digital clocks don't read the same within 1 second, it irritates me...LOL. My wife says that if I am not good and go to hell, Satan will put me in a room full of clocks and no two will read the same.
That being said, I wonder whether this process of lens calibration will make me a little bit more frustrated than satisfied. Repeatability concerns me too. If all the conditions are right including a steady battery powered light source and the focus wanders, what am I checking...a little reduction in typical error?
I'm also considering LensAlign. That makes me wonder why not use it alone. Can't you visually and quickly see where the sharpest adjustments are and hone in on that as opposed to checking several groups of 5 unit intervals along the entire range? Also, wouldn't the visual check on the ruler give you a quicker answer that's realistically as good as it can get?
The instructions with FocusTune indicate that centering the lens axis with the target is not critical, but having the plane of the target parallel to the sensor's plane is. If that is not true, using a paper target seems futile.
I've been a little long winded, I know.
Scott Chapin Powder Springs, GA, USA Nikonians Team Member