Little Tuna - AF Adjust - Some questions ... and a bug

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Paul Richman
Paul Richman Veteran Member • Posts: 4,016
Little Tuna - AF Adjust - Some questions ... and a bug

Well it turns out that my brand spanking new little tuna did need some AF adjust.  I've read some of the threads here about AF adjust, and learned the most so far from glassaholic and Phocal, so thanks for that!

One of the most important things I learned (thanks glassaholic!) is that C-AF on stationary subjects is not advised.  Indeed, with some earlier test shots with closer subjects (~3 - 4 meters), I got poor results at F/2 with C-AF.

I decided to do a manual test with my favorite subject, at about 3 - 4 m):

This shot has the AF +1 that I found to work best

But I had some strange results, which I'm going to call Olympus tech support about, as I believe I found a firmware bug.

So here's what I did, after a number of prior failed experiments.  I used only F/2.  On tripod with 2 sec timer.  I took one MF shot.  (These have been very consistent and sharp.)  Then I took two S-AF shots at each AF adjust from -1 to -5 and +1 to +5.  Also one AF shot with no adjust (more about this below, under the heading of "bug").

Then I loaded all the shots into layers in Photoshop and compared their sharpness at 1:1.

I found the two AF+1 shots to be the sharpest.  However, the following were very very close:  AF-1, -2, -3 and one of the two +2 shots.  This seems strange.  Phocal points out in another thread here that AF is inconsistent and much repetition may be needed for proper AF tuning. Perhaps that explains my results here as being not statistically significant?  Dunno'.  Of the 10 duplicate (same AF adjust) shots I took, 8 of the duplicates sharpness matched each other.

As for the firmware bug, I found that several times the AF adjust was summarily dropped by the firmware.  I carefully looked at the Info on each shot review to see what the AF+/- was, and several times it was blank.  Simply taking another photo would produce a shot with the correct AF+/-.  That's not good!

I'll let you know what Oly support has to say about that.


And some little tuna flower shots at F/4 just for grins:

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Paul Richman
Pixels By Paul
"There's a good picture nearby. Find it. Take it. Share it."

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Olympus PEN-F Olympus E-M1 II Panasonic Lumix DC-G9 Olympus Zuiko Digital ED 150mm 1:2.0 Olympus Zuiko Digital 300mm 1:2.8 +11 more
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