Currently IMatch uses one of the following tags to figure out which lens was used with a given item:
Composite\LensID\LensID
Exif::Main\42036\LensModel
Exif::Main\42034\LensInfo
Composite\LensID-4\LensID
Composite\LensID-3\LensID
Composite\LensID-2\LensID
Composite\LensSpec\LensSpec
The one problem with this list is that none of these tags are settable in XMP, and thus a elns model cannot be added to a file by putting it in an XMP sidecar file. (Not all EXIF tags have XMP counterparts, so while it's possible to put, for example, EXIF GPS data in a sidecar, lens model and info cannot go there.)
I'd like for the list above to be extended with XMP::exifEX\LensModel\LensModel\0, as it is the XMP equivalent of Exif::Main\42036\LensModel
The lens is a non-writable tag for good reasons. Adding a wrong or invalid lens can break files in RAW processors, because RAW processors use the lens to configure certain processing options. I have no idea what happens if you change the lens model only in Exif Extended, but have no match in the original EXIF lens data...
All true, but if the file you're dealing with doesn't have any lens information you are effectively stopped from fixing it, as things are now.
But this is a global setting, immediately affecting all new and existing databases once I roll it out...
True. :(