On Fri, Nov 18, 2016, at 06:14, Chris Chiappa wrote:
> > I have the Oly, and it's a great little lens, but does need a fair
> > amount of correction, which is well provided for in lensfun currently
> > (I spent some time getting the vignetting right, which varies quite a
> > bit with focus distance, in such a way that always applying the
> > correction for infinity does some not-so-nice over-correcting at close
> > range).
> Hi, I believe that I was the one who submitted the original data for
> this lens. I only calibrated at infinity because my camera at least
> (Panasonic GX-7) does not seem to record the focal distance anywhere I
> can see in the EXIF. Do other cameras do better here, or do you just
> do a lot of manual fiddling with the correction?
The Olympus E-PL6 gives reliable values for focus distance in exif tag 0x0305,
which at least exiftool knows about:
http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/Olympus.html
I don't know about previous Olympus m43 models, but I do know that while the
field existed in my XZ-1 and XZ-2 compacts, it was pretty much garbage. It's
useful information for vignetting correction on at least *some* lenses, so
hopefully it will become common. There's no similar FocusDistance tage listed
for Panasonic, though, as far as I can tell:
http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/Panasonic.html
although I suppose it's possible that it exists but hasn't been "discovered"
yet...
Incidentally, I've been using the following correction line in my personal
lensfun database for the 25/1.8, it uses the simpler, less computationally
expensive poly3 model, which seems well suited to the distortion of this lens:
If you agree that it performs well, it could be swapped into the official
database...
--
jys
--
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