I sorted out all my photos and then created a backup of the drive. After that if I added any photos to the master drive, as I expected, a few photos were found when I re-synchronised and copied to the backup drive.
I then decided to have a look at Picasa as a means of cataloguing and also to make use of the facial recognition facility to help find and name images that still were called the like of "img1234.jpg". The only problem is that afterwards, when I then came to synchronise, there were hundreds of, though not all, photos that needed synchronised from left to right (master to backup). I think that photos where facial features have been identified have been changed in some way.
My main concern is to try and retain the original date the photo was taken. There seem to be several dates stored, and logically created date would be the one I would expect to be fixed, though it does not appear to be as many seem to have changed to wrong dates over the years so other software has changed them.
Sorry - I realise this is not strictly an Opus question but it is related so I hope someone will be able to answer my query.
Ian