[SOLVED with custom .ini + wrong version by user] Tamron lens recognition on Canon body (or can I manually update Exiv2 on dt 4.8.0 for Windows?)

Software darktable
1

Hi everyone, new user on the forums, I’ve been having fun exploring this software and already started teaching it to some fellow photographers whenever I can help them.

I’m currently having an issue though, inspired by a number of threads on failed lens recognition I thought about bringing my case forward to avoid the risk of going OT in other discussions.

The lens I’m having issues with is the “Tamron 18-200 mm F/3.5-6.3 Di II VC” and I have a recognition issue which was (supposedly) solved in v 0.28.3 of Exiv2.

This lens, oddly enough, is the only one which does not feature the brand name in the supported Tamron lenses list. It also has AF as part of the nomenclature which isn’t specified on the official website, on lensfun’s list, neither in the exif data but appears like this on dt.
It seems like there might be some confusion, should I be worried? Could it be leading to errors in the recognition other than the aforementioned behaviour solved in Exiv2’s update? I even thought I could be completely wrong, and that it isn’t the same lens, but there’s nothing really similar after doing some researches.

This is how it appears on dt 4.8.0 on Windows:
immagine

This is how it appears on lensfun’s list:
Screenshot 2024-07-11 at 01-13-13 Lensfun

This is what it looks like in ExifToolGUI
immagine

Right now Exiv2’s lib featured in dt 4.8.0 uses LensType instead of LensModel to determine the lens which results in wrong reading for third party lenses on Canon as stated in the discussions over GitHub where they discussed the update.
It seems like the problem is solved, and I was curious to verify if it’d help me.
I already tried the suggested “Exiv2.ini” method, which at first seemed to solve the issue but, alas, it results in a “lens not found” in every way I write it. Otherwise, could it be because of some errors in the LensModel name that mess up the recognition? In the exif data the name seems to have an error as in Di II being attached, it turns out like this: “TAMRON 18-200mm F/3.5-6.3 DiII VC B018”.

Otherwise, I was wondering if a non-linux user could “build” a version of dt with the updated Exiv2 library to test if it fixed this lens in my case or if a solution is to be found elsewhere.

Sorry for the lengthy thread, I wanted to clarify as much as possible, and I’m ready to provide EXIFs or RAWs if need be.

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The problem you have is not w/ exiv2 (the 0.28.3 fix was for the Nikon bodies, btw, the Canon string was already “normal”) nor dt, but lensfun database. (Yes, it is all very confusing, but all 3 pieces of the puzzle have to match up.) I’m very surprised the lensfun db shipped w/ dt 4.8.0 installer is not up to date? @wpferguson

It’s not straightforward to update on Windows unfortunately, but it is doable. Please search the forum, as it has been covered several times already.

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Actually, just checked the dt 4.8.0 installer - it does ship a fairly recent lensfun db (Jun 06 2024 05:48:32) w/ the corrected lens string, so I have no idea how your screenshot above could be showing the old one…

How did you install dt 4.8.0?

And to make sure, the “image information” panel on the left does show the expected “Tamron 18-200 mm F/3.5-6.3 Di II VC” string?

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Thank you for taking the time to reply.

The version of dt I downloaded is the .exe from the website, I unfortunately deleted the setup from the downloads, but I know I installed it on Jun 14, I’m on Win11 btw.

The image information on the left in Darktable reads Canon TS-E 90mm f/2.8 which in the exif data corresponds indeed to “LensType: Canon TS-E 90mm f/2.8 or Tamron Lens” which corresponds to the number 127.

What I tried when noticing it was making an Exiv2.ini as follows (and refreshed the exif in dt afterwards):

[canon]
127=TAMRON 18-200mm F/3.5-6.3 DiII VC B018
5

Then it can’t be 4.8.0 as it was released on the 22nd.

Please try again.

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Woah, thank you for letting me notice, I got confused because I also installed it on two other machines on different dates.

Okay now I got it, I thought for the whole time I had the latest version on my pc.

Btw on the left panel my photos without exiv2.ini still read the Canon lens, I’ll try to make the Exiv2.ini again

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Okay, with the Exiv2.ini it works. Thank you for your support, deeply appreciated!

2 Likes
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The second step of any build I do is to update the lensfun database. Therefore worst case would be no update, so the database would be 1 week old.

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