#18 Sigma 19mm 2.8 EX DN ( E Mount ) + Sony A6000 ... combination not recognized

[Rodrigo De Leon]

Hi.

I have a Sony A6000 and a Sigma 19mm 2.8 EX DN lens (the OG model).

According to the LensFun coverage page:

http://wilson.bronger.org/lensfun_coverage.html

... support is present for the lens.

Using darktable 1.6.2 and liblensfun 0.2.8, the camera/lens combo was not recognized at all from the RAW metadata.

I manually updated to liblensfun 0.3 and camera/lens auto detect would not work. I could manually select the camera/lens combo, though.

I noticed that the RAW EXIF data shows:

"E 19mm F2.8"

... as the lens model, but the liblensfun xml file shows:

"Sigma 19mm f/2.8 EX DN"

... as the lens model.

Relevant snippet:

<lens>
    <maker>Sigma</maker>
    <model>Sigma 19mm f/2.8 EX DN</model>
    <mount>Sony E</mount>
    <mount>Micro 4/3 System</mount>
    <cropfactor>1.534</cropfactor>
    <calibration>
        <!-- Taken with Sony A6000 -->
        <distortion model="poly3" focal="19" k1="-0.00748" />
        <tca model="poly3" focal="19" br="-0.0000466" vr="1.0003817" bb="0.0000346" vb="1.0000194" />
    </calibration>
</lens>

Anyways, I opened a ticket on darktable redmine, lots more detail there:

http://www.darktable.org/redmine/issues/10331

They pretty much told me it's not a darktable bug, so I'm trying my luck here.

Basically, how can I force detection of the lens model?

Or is there nothing else to do on LensFun's side?

Thanks for your time.

Regards.

[Torsten Bronger]

The problem is the "E 19mm F2.8" written by the camera to the RAW. You may ask the exiv2 people to do something about it (e.g. mapping it to something more useful) but if Sony themselves publish a 19mm than this may become ambiguous. So it may be a limitation that cannot be fixed.

You can solve the problem locally on your computer by copying the lensfun entry into an XML file in ~/.local/share/lensfun and changing the lensmodel name in there to "E 19mm F2.8".

[Rodrigo De Leon]

Thanks. Will try.

Regards.