I've followed your and others focusing tools trial and tribulations since July 2012. I'm still not a fan of generally using focus tuning and think that FoCal is charging for beta testers. From everything I've read it is simply to buggy to product for the masses. However if people are willing to buy the buggy stuff it does provide funds for them to develop a better tool.
I was taught that once focused on a spot, abut 1/3 of the area in front of and 2/3 behind the focused spot would be the depth of field. But I don't see people setting up their focus points that way and not sure if it is taken into consideration into the software programs. But I will admit this would be critical for only some situtaions.
I have not spent nearly the time you or others have in testing but my experiences demonstrated to me that focus adjustments are only valid: - at the distance tested (more on this in the post) - for temperature tested at (tested at 35 depress difference in temperature with significantly different results) - and the lighting conditions for the test (from test done in bright shaded area to inside using tungsten)
And zoom lenses would tend to significantly complicate matters unless that lens is used for a pretty specific purpose. All of my zooms are used throughout their focal range and distance anywhere from the closest point of focus to infinity. None of the lenses have a setting that I use enough to dedicate focus tune for that one setting.
I have an 85mm f/1.4 lens that I know is off and was kind of tired of dealing with it. So I bought FocusTune. Under the same conditions I can duplicate the same results. And with AF Fine tune set and on for portrait, it is spot on. To me that validates the software, my procedures, and the equipment issue. Here are the results, and what should I use for my final AF Fine tune setting? @ 3 ft = 0 @ 7 ft = -20 @ 10 ft = -20 @ 14 ft = -10 @19 ft = -10 @23 ft = -5
- If I set it at -10, I would have better results for everything past 6 feet. But at 7 ft and maybe 10 feet the setting might not fall within the depth of field and not achive what I'm after. And if shooting anything at minimum focus distance, focus would be significantly worse. I did not see where -10 would be an issue past 20 feet as the depth of field would hide the focusing error.
But my biggest issue was with portraits, so I set AF Fine Tune at -20 and turn AF Fine Tune on for portraits and then off when I'm finished. This is livable and better.
Either I don't seem to understand how AF Fine Tune is beneficial for zoom or it is pretty complicated - Since I use my zooms across the spectrum I would test at 3 zoom settings at 3 different distances for each setting. So now I've got nine sets of test to balance out!
And for something like the 70-180 Micro, between macro shots and normal zoo, woah. But when I get time I will test it at a macro setting because I really want to know how much I lose when shooting at f16 and above.
Anyway, that's my two cents worth. So even though I'm not a fan I'm seeing some benefit.