Tamron SP 15-30mm F/2.8 Di VC USD G2 A041 is showing up with the Exif.CanonCs.LensType from another lens (35-150)

[eldoradobirds]

When I look at the exif in a Windows Photo Processing Tool like Canon DPP I just see the lens identified as the Tamron SP 15-30mm ... which is correct. When I use the exiv2 command below in linux I see the Exif.CanonCs.LensType field as another lens which then (wrongly) shows up in Darktable (linux) lens correction window. Note that the Exif.PhotoLensModel and Exif.Canon.LensModel fields match the lens.

$ exiv2 -pt 9M6A3718.CR3 | grep -i 'lens|model|make'
Exif.Image.Make Ascii 6 Canon
Exif.Image.Model Ascii 13 Canon EOS R5
Exif.Photo.LensSpecification Rational 4 15/1 30/1 0/1 0/1
Exif.Photo.LensModel Ascii 42 TAMRON SP 15-30mm F/2.8 Di VC USD G2 A041
Exif.Photo.LensSerialNumber Ascii 11 0000000000
Exif.CanonCs.LensType Short 1 Tamron 35-150mm f/2.8-4.0 Di VC OSD
Exif.CanonCs.Lens Short 3 15.0 - 30.0 mm
Exif.Canon.ModelID Long 1 EOS R5
Exif.CanonFi.RFLensType SShort 1 n/a
Exif.Canon.LensModel Ascii 138 TAMRON SP 15-30mm F/2.8 Di VC USD G2 A041

Note sure what is wrong here.

[kmilos]

Which exiv2 version? Please try w/ latest 0.28.3, there have been some recent fixes specifically around detection for Canons...

Note that the Exif.PhotoLensModel and Exif.Canon.LensModel fields match the lens.

darktable (for whatever legacy reasons) uses only Exif.CanonCs.LensType for Canon SLR (i.e. non RF) lenses.

[kmilos]

Also, it looks like neither exiv2 nor exiftool have this specific G2 lens in their databases (only the older A012 version), so please feel free to contribute a PR.

In the meantime, you can use the exiv2 config file workaround.

Edit: found some samples.

[eldoradobirds]

Thanks for the info about Darktable only using the LensType. I tried to use exiv2 to modfiy but get this:

$ exiv2 -m cmd.txt 9M6A3718.CR3
Warning: Exif.CanonCs.LensType: Failed to read Short value "TAMRON SP 15-30mm F/2.8 Di VC USD G2"
Exiv2 exception in modify action for file 9M6A3718.CR3:
Setting Image comment in BMFF images is not supported

$ more cmd.txt
set Exif.CanonCs.LensType Short TAMRON SP 15-30mm F/2.8 Di VC USD G2

Not sure what BMFF means but it seems like this field can't be modified?

[eldoradobirds]

Also tried adding an .exiv2 file but it did not seem to work.

$ more .exiv2
[canon]
Tamron 35-150mm f/2.8-4.0 Di VC OSD=TAMRON SP 15-30mm F/2.8 Di VC USD G2

$ exiv2 --print t --grep lens/i 9M6A3718.CR3
Exif.Photo.LensSpecification Rational 4 15/1 30/1 0/1 0/1
Exif.Photo.LensModel Ascii 42 TAMRON SP 15-30mm F/2.8 Di VC USD G2 A041
Exif.Photo.LensSerialNumber Ascii 11 0000000000
Exif.CanonCs.LensType Short 1 Tamron 35-150mm f/2.8-4.0 Di VC OSD
Exif.CanonCs.Lens Short 3 15.0 - 30.0 mm
Exif.CanonFi.RFLensType SShort 1 n/a
Exif.Canon.LensModel Ascii 138 TAMRON SP 15-30mm F/2.8 Di VC USD G2 A041

[kmilos]

I tried to use exiv2 to modfiy

I never mentioned the exiv2 -m modify command... It might not be a good idea to ever tamper with your raw files...

$ more .exiv2
[canon]
Tamron 35-150mm f/2.8-4.0 Di VC OSD=TAMRON SP 15-30mm F/2.8 Di VC USD G2

Of course this doesn't work, you need an ID number to string mapping...

[kmilos]

So:

[canon]
117=Tamron SP 15-30mm f/2.8 Di VC USD G2

[eldoradobirds]

Thanks. I see it showing the correct info now in the exiv2 command and in Darktable.

$ exiv2 -pt 9M6A3718.CR3 | grep -i 'lens|model|make'
Exif.Image.Make Ascii 6 Canon
Exif.Image.Model Ascii 13 Canon EOS R5
Exif.Photo.LensSpecification Rational 4 15/1 30/1 0/1 0/1
Exif.Photo.LensModel Ascii 42 TAMRON SP 15-30mm F/2.8 Di VC USD G2 A041
Exif.Photo.LensSerialNumber Ascii 11 0000000000
Exif.CanonCs.LensType Short 1 TAMRON SP 15-30mm F/2.8 Di VC USD G2
Exif.CanonCs.Lens Short 3 15.0 - 30.0 mm
Exif.Canon.ModelID Long 1 EOS R5
Exif.CanonFi.RFLensType SShort 1 n/a
Exif.Canon.LensModel Ascii 138 TAMRON SP 15-30mm F/2.8 Di VC USD G2 A041

Is there some way to query to get the ID number for a lens in general?

Also, this lens is an EF mount lens so the lens correction module in Darktable only seems to let me pick a Canon camera that is EF mount. However, Canon RF mount cameras can use the EF to RF adapter. Maybe this is some issue with the lensfun database?

[kmilos]

Is there some way to query to get the ID number for a lens in general?

It was in the config file instructions: use -pv instead of -pt

Maybe this is some issue with the lensfun database?

Quite possible indeed.