transference of photos and retaining metadata

There are two kinds of metadata involved when you consider jpeg or other image file.

One is the file data. This is what the Finder shows. This tells you nothing about the contents of the file, just the File itself.

The problem with File metadata is that it can easily change as the file is moved from place to place or exported, e-mailed, uploaded etc.

Photographs have also got both Exif and IPTC metadata. The date and time that your camera snapped the Photograph is recorded in the Exif metadata. Regardless if what the file date says, this is the actual time recorded by the camera.

Photo applications like iPhoto, Aperture, Lightroom, Picasa, Photoshop etc get their date and time from the Exif metadata.

When you export from iPhoto to the Finder new file is created containing your Photo (and its Exif). The File date is - quite accurately - reported as the date of Export.

However, the Photo Date doesn't change.

The problem is that the Finder doesn't work with Exif.

So, your photo has the correct date, and so does the file, but they are different things. To sort on the Photo date you'll need to use a photo app.

Do you want to save the original image files or the adjusted versions of your photos, or both?

You are right, exporting your photos may change the file creation date, but Photos will embed the capture date of your photos in the EXIF tags of the exported photos. If you open them in Preview or any program that understands EXIF tags, you will see the original capture tag.

• If you export the edited versions with "File > Export > Export ... Photos" all titles and descriptions and keywords will be included in the IPTC metadata. You can see them with "File > Get Info". Use the subfolder format "Moment Name". Then the photos will be saved in folders, named by the date and the location.
• If you export the edited versions with "File > Export > Export .Unmodified originals" enable the checkmark "export IPTC as XMP". Photos will write XMP sidecar files with the metadata, and when you import the photos to another Photos Library, the title, keywords, descriptions, GPS will be restored from the sidecar files.

I would simply copy the complete Photos Library to an external drive and let it sync with iCloud to download the originals (with Optimize Storage" off. Once all photos and originals are save in the library on your external drive, switch iCloud back to the internal drive and you can delete photos from the library on your internal drive to have a smaller library syncing with iCloud.

You can only sync a Photos Library with iCloud Photo Library.

• Drag your Photos Library to the external drive.
• If you do not want all photos to sync with iCloud, duplicate the copy on the external drive. One copy will be an archive of all your current photos and one will be the local copy of your iCloud Photo Library.
• Double click the copy that you want to sync with iCloud Photo Library to open it in Photos. weed it out a bit by deleting all photos you do not want to have in iCloud.Empty the Recently deleted album occasionally, so it will not get too full.
• Once you are happy with the selection of photos for iCloud, while viewing the pruned library for iCloud,
  • open the Photos Preferences > General . Enable "Use as System Photos Library":
  • open the Photos Preferences > iCloud .
    • Enable "iCloud Photos Library"
    • Enable "Download Originals to this Mac"
• Now wait for your smaller library to upload to iCloud Photo Library. This may take a few days, if the library is large.
• Then create a new, empty library on your Mac in the Pictures folder.
• To create the empty library, quit Photos, hold down the options key ⌥ while launching Photos and select to create a new library from the dialog panel that will appear. Select your Pictures folder as the destination. Name the new Library "Local iCloud Photo Library" or similar. Now make this library the System Photo Library and your iCloud Photo Library: while viewing the new "Local iCloud Photo Library"
  • open the Photos Preferences > General . Enable "Use as System Photos Library":
  • open the Photos Preferences > iCloud .
    • Enable "iCloud Photos Library"
    • Enable "Optimize Mac Storage"
  • Wait for the icLoud Photo Library to download to the Mac.

You can use iCloud Photo Library with optimized photos on yu mac to reduce storage requirements

You can make a copy of your Photos library and archive it adn then delete photos from your existing library

you can export (fil menu ==> export) either the current of the modified version with the desired metadata and it will not be changed since it is part of the photo

Do not confuse the file metadata with the photo metadata - two completely different things

LN

I seem to remember that I copied a lot of photos to a flash drive for my daughter over a year ago, and using "export unmodified originals," the copies retained the original date the photo was taken.

If you are using iCloud Photo Library and the original image files get copied back and forth between iCloud and your Mac the file creation date may change. If your photos library is not syncing with iCloud Photo Library you may be lucky and the original file creation date may still be available when you are exporting the unmodified original.

From this error message it appears that your Photos Library on your Mac is already syncing with iCloud Photo Library. And it is an optimized library.

What has happened is, that you copied a library from your Mac to the external drive, and because because the internal library is "optimized" (meaning, that some original image files are missing), the copy has items, that are incomplete and cannot be sed, if you do not enable iCloud Photo Library. You are still having the library on your internal drive, right? Then you can click the button "Delete incomplete items". They will only be deleted from the copy of the library, not from iCloud.

Then enable iCloud Photo Library for this library, so the missing photos can download from iCloud to the copy.

Once you have a copy of your library on your external drive, with out "Optimize Mac Storage", and the syncing has finished, try to create the archive copy. If the syncing finished and all originals have been downloaded, you shroud no longer see the warning about incomplete items, when you duplicate the library.

but I'm left with a blank screen and the wheel is still going round. Is that the sync process?

I hope so. It can take a long a time, I,e, if the internet connection is slow.