Find photos in old backups

QI traded in my old iMac for a new one, which went back to Apple after I had backed it up and migrated. Now I can’t find some old photos, and my backups start with the new Mac. Where have they gone? bySTEPHENCAMERON

AIf your old Mac was still backing up using Time Machine to a volume started before Big Sur, and certainly if it was still running Catalina, then its backups will have been stored in HFS+ format. Your new Mac, though, runs Monterey and will back up to a fresh APFS volume on the backup disk.

So long as your old backups still remain on that disk, you can access them through the Finder. They should appear on your Mac as another volume, at the top of which is a folder named Backups.backupdb, containing folders with all your old backups inside them.

If you can’t find that old volume with its backups, then it’s possible Time Machine reformatted it to store your new backups, which look like a long list of backups, each containing a disk. If so, your old backups have now been lost and can’t be recovered.

When upgrading your Mac, the best plan is to archive its old backups for future reference, and start a new backup series ideally on a fresh disk.

Backups made by Time Machine to APFS volumes have a distinctive structure, very different from those on HFS+ volumes.