Auto-Focus Fine Tuning ( I think Canon's is called Micro-Adjustment)

[jprzybyla]

A while back there was a thread on auto-focus fine tuning. I wrote in response to be careful because from personal experience one can make a perfect lens/camera combination not focus correctly. Since responding to that thread (after receiving my camera back from Nikon Repair Service) that the lens/camera combination was not focusing correctly. In repairing my camera the Nikon service tech re-aligned the mirror. I believe that is what changed how the camera and lens worked together. That being said I tried various ways to correct the focusing problem without success until I discovered the method in the thread I will post below. The instructions in the thread explains it better than I can. If you are having problems with the camera/lens combo focusing you might consider giving it a try.


http://www.dpreview.com/forums/thread/3377109

[dje]

Thanks for that link Joe. I've been meaning to have a look at AF Fine tune on my gear for a while now so your post is a timely reminder. It looks an interesting approach, certainly worth a try.

I guess with this method and several others, it's important to get the initial MF "reference" as accurate as possible. Interestingly there is a reference amongst the comments on that thread to a neat test pattern which should help in this regard.

Dave

[inkista]

Another way to learn Dot-Tune, is this youtube video by the guy who came up with the idea.

And for the Canon shooters with MagicLantern loaded, there's auto Dot-Tune:

[dje]

I guess with this method and several others, it's important to get the initial MF "reference" as accurate as possible. Interestingly there is a reference amongst the comments on that thread to a neat test pattern which should help in this regard.

Dave

Well I tried out this method on my D610 with reasonable success I believe. Some observations

I found Contrast Detect AF in LV mode gave a more consistent reference focus than Manual Focus in LV mode. In the process of testing this I switched to a printed test chart as per the updated one referenced in Kathy's first video.

I took a number of sets of readings for each lens (at their most commonly used focal lengths) and averaged the mid-point result. The variance in the mid point values was typically 1-2 for my three lenses.

I've saved the calibrations in camera but at this stage I haven't tried any "real world" shooting. My adjustment values were not large (-2, -6 and -7 for my three lenses respectively) so I doubt that I will see much difference. However if you don't try it, you'll never know !

Dave