Lens data

[Roblister]

I hope I am posting this in the correct section of the forum.
I use an excellent piece of Mac software called HoudahGeo which manipulates location data to geotag images and uses exifTool to write the data.
Although I only needed the location metadata added I noticed the contents of the Lens data field had changed from "EF24-105mm f/4L IS USM"  to  "Canon EF 24-105mm f/4L IS".  Pierre at Houdah explained that this was a side effect of HoudahGeo using exifTool to update the data and that exifTool has the lens names listed in the HoudahGeo.app/Contents/Resources/lib/Image/ExifTool/Canon.pm file.  Although this entry could be edited is there another suggestion I could pass on that would eliminate the problem.
My concern is that a search using lens metadata could give unpredictable results.

[Phil Harvey]

There are 2 distinct aspects to this problem:

1) ExifTool decodes a numerical lens identifier according to the lookup tables in Canon.pm as you mentioned.  Some Canon models also store lens names as strings in the metadata, and the strings that Canon uses may be different than those generated by ExifTool.  Unfortunately, there is no way around this since there is no way that Canon will ever support all of the 3rd party lenses that ExifTool recognizes.  ExifTool includes the make in the lens string to differentiate Canon lenses from Sigma, Tamron, etc.  But Canon of course doesn't care about those other makes.

2) HoudahGeo is changing the "Lens Data" field in your images.  I don't understand why this should happen if you are just geotagging images.  This is a HoudahGeo feature, and not an ExifTool problem because ExifTool gives complete control over the metadata that is changed.

- Phil

Edit: Fixed typo

[Roblister]

Thanks for the reply and explanation Phil that makes a lot of sense.  I will go back and see if Pierre has any ideas within his software.