Juha Kannisto Offline Upload & Sell: On
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DavidBM wrote:
Yeah it's weird.
There are many EXIF fields associated with the lens; LensModel, Lens, and LensID amongst them.
Manufacutuers aren't always consistent with which fields they use...
Lens Model EXIF field is perhaps the most reliable, but not always.
Lens Info sometime has name, sometimes just focal length and aperture.
Lens ID is a derived field, maybe based on Lens Model, or ors other stuff?
There are Maker Notes fields which are relevant too:
Lens Type2 for instance, tends to be where CV puts lens names recently.
Sometimes Lens Type has the name too, sometimes garbage.
So here's my guess: because of this randomness, early on the CV developers decided to have their own database of lens names, and use specs to pick the lens. It was a bad idea, because eventually there would be many lenses with the same spec, and it required them to update their own database. But I can see how it may have been tempting early on.
But now it really has to change, just read all the relevant fields, and have an algorithm to guess the most likely real name. I'll bet that's what Adobe does (or maybe they know, for each brand and era, which field is the reliable one. Also not hard....Show more →
I think the old Loxia lenses didn't have clear information on the Lens Model and Lens ID fields (I used to have Loxia 50/2) and that might have been one reason that C1 had to rely on some other info from EXIF to try to identify those lenses. Yesterday I reported the problem about CV 35/2 getting recognized as Loxia 35/2 and Sigma 65/2 getting recognized as CV 65/2 to C1 Support just in case although they might have received reports on these from others already...
CV 35/2 has "Voigtlander APO-Lanthar 35mm F2 Aspherical" in Lens Model and Lens ID fields. It has "Unknown (51006)" in Lens Type 2 field.
Sigma 65/2 has "65mm F2 DG DN | Contemporary 020" in Lens Model and Lens ID fields and "Unknown (50523)" in Lens Type 2 field.
I also checked Sony 40/2.5 G just for reference and it has "FE 40mm F2.5 G" in Lens Model, Lens Spec and Lens ID fields. It has "Unknown E-mount lens or other lens" in Lens Type 2 field.
I suppose in most cases with recent lenses it should be possible to try to identify the lens based on Lens Model or Lens ID fields. I think if and when there is no C1 in-built lens profile match, C1 will currently pick up the lens name from one of these EXIF fields as-is and will copy that name to it's own metadata. E.g. 40/2.5 G appears as "FE 40mm F2.5 G" in C1 metadata and it doesn't have any profile match (so manufacturer profile will be used automatically). The lens name problem seems to be just happening with the lenses that get incorrectly matched like CV 35/2 and Sigma 65/2 currently.
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