There are many different Date/Time tags but what I am trying to find is the "lowest common denominator" of the Date/Time that the file was first created. I assume, for an image file from a camera, that this would be EXIF:DateTimeOriginal, but I have come across an app that, unless the box for IPTC is checked when exporting a copy of an image, the date shown in macOS Finder, on the copy, for when its content was created, shows the date when the exported file was written, not the original date from the source file.
Can anyone clarify which tag is not getting written on export, especially the "root" tag if any "shortcuts" or redirections take place?
Any image directly from a camera should have all the three major EXIF time stamps, DateTimeOriginal, ModifyDate, and CreateDate (all covered by the AllDates shortcut).
My guess is that when exported, none of this is copied and finder is forced to use the file system time stamps, FileModifyDate and FileCreateDate.
The only advice is to run the time listing command on the file and see what still exists.
exiftool -time:all -G -a -s file.jpg
There's not much you can do if the other app doesn't correctly export the data.
Thanks for confirming my suspicions.
The weid thing is that the previous versions (plural) all used to export the EXIF:DateTimeOriginal tg but, with this version, they've decided to split what metadata gets exported in order to include more IPTC if the user chooses.
And, for some inexplicable reason, I have just been told that, in fixing the missing EXIF tag, they're also wanting to export the IPTC tag, even though the user can uncheck the box to prevent export of IPTC.
In all the thirty plus years I have been developing software, I have never come across such odd thinking when it comes to metadata handling