backup photos on external h.d.
I have a 4tb Seagate backup plus. On time machine, it appears only the desktop stuff from long ago is there. When I click on pictures or movies, I just get a window that says there are 28g of photos--I can't see what was on it on that old date and it opens the photos that are on of my computer today.
I'm afraid it's not backing up all my movies & photos (since this happened to a friend). nothing is excluded from the backup and I am not using the cloud as a backup location. software is up to date. using imac, el capitan v10.11.6.
I took the h.d. to view on another mac and they couldn't see any pics, just that the size of photos file was 28g.
To alleviate the fear that the h.d. is not backing up my photos, how do I see the photos and everything else on the h.d. itself?
MacBook Pro, Mac OS X (10.5.8)