One of my pet peeves, from my previous DSLR experience with a D200 and various Nikor AF lenses, has been that AF does not routinely produce tack sharp focus. The focus is almost always good, but not tack sharp (I know - it is not a well defined term).
I noticed that the new D610 has an 'AF Fine Tune' option in the Setup menu that allows for establishing an incrementally nearer or farther focus point for each of up to 12 lenses. Interestingly, the User's Manual recommends NOT using this feature except "when required," whatever that may mean.
Before I launch off into a series of experiments, can any D610 users comment on their experience with this option? Does it produce useful results? Does the correct focal point correction vary with focal distance? Does the correct focal point correction vary with time, temperature, or other common variable?
Given the proliferation of bracketing options that are provided with the camera, this might have been an interesting additional bracketing option to have provided.
#1. "RE: D610 Auto Focus Fine Tune" | In response to Reply # 0briantilley Nikonian since 26th Jan 2003Sun 05-Jan-14 12:09 PM
Nikon's guidance for the use of AF Fine Tune is wise. The feature is intended to be used when a given lens/camera combination exhibits a consistent focusing error that is obvious in everyday use - and in those circumstances it can be very useful. Many times, focus errors are due to other factors such as inappropriate AF settings or low-contrast subjects.
As you seem to suspect, the amount of fine tune required will usually vary with focus distance, and sometimes with aperture. For zoom lenses, it also varies with focal length. The snag in its use is that applying an adjustment that improves things at one focal length and distance might make things worse at another.
Using the feature also requires a robust and reliable testing set up.
AF Fine Tune is a nice feature, but one to be employed with care and awareness of the pitfalls