2 Replies Latest reply on Mar 31, 2015 2:06 PM by johnrellis

    Updating adjusted date/time fields from metadata


      My workflow involves both Lightroom and Photo Mechanic. I keep both programs in sync by writing my edits to xmp files. This lets me change color flag, star rating, keywords, etc. using either program.


      When I adjust the capture time of photos using Lightroom, only the "Date Time Original" field gets updated. However, there are also exif values for "Date Time Digitized" and "Date Time" (edited). I understand the semantic difference between what these three values are supposed to mean, but if the original digital camera's clock was wrong, I should be able to *fix* all of them. At least Date Time Digitized.


      All three of these values are stored in both the raw file metadata, and the xmp file, just like Date Time Original. Photo Mechanic and the command line exiftool can update all three values in both kinds of files.


      Is it possible to force Lightroom to reread these values from the files? It seems like the catalog completely ignores them no matter what, after the initial import. Is there a reason for this? I've tried Synchronize Folder, and even Metadata > Read Metadata from File. Everything else in the metadata gets synced except for the date time values.

        • 1. Re: Updating adjusted date/time fields from metadata
          johnrellis Most Valuable Participant

          Metadata > Read Metadata does indeed correctly read date/time values from the metadata.  But some gotchas to be aware of:


          - For JPEGs and TIFFs, the metadata is always read/written to the .jpg or .tiff file, never from an associated .xmp sidecar. 


          - For raws, LR reads/writes the .xmp sidecar; if no sidecar is present, it reads from the raw and writes to a sidecar.  There is a preference setting to cause LR to write back to the raw as well.


          - There are three metadata sections where LR (and other programs) read/writes photo date/time metadata: XMP, EXIF, and IPTC.  When writing updated values, LR changes all three sections.  When reading, LR examines all three sections, and uses the rules in the Metadata Working Group spec to choose which to use if there are conflicting values.   So when you use an external tool to change the metadata date/times, its best to update the date/time in all three, or update one and delete from the other two.  I have no idea what Photo Mechanic does, but Exiftool in general does not update all three sections (since the corresponding field may have a different name in each section).

          • 2. Re: Updating adjusted date/time fields from metadata
            johnrellis Most Valuable Participant

            LR provides no way to change DateTimeDigitized -- you'll have to use an external tool or use one of the plugins that let you invoke Exiftool more conveniently from within LR.


            One version of LR years ago changed the Edit Capture Time command to also update DateTimeDigitized, but Adobe promptly backed out that ill-considered change in the next release.  A fair number of people use LR to also manage scans in which DateTimeDigitized differs from DateTimeOriginal, and the Edit Capture Time was wiping out that carefully entered metadata.   I think Adobe figured that almost all users of digital cameras don't really care about DateTimeDigitized since there cameras don't add that field, so it wasn't important for Edit Capture Time to update it.    


            Of course, it would be better for LR to let you edit it explicitly.