Ask HN: How to privately share photos/videos from multiple devices

We probably have a typical tech household setup: multiple phones, several camera's (DSLR, action cameras, drone) and multiple laptops and a desktop. We generate currently 40K photos and 5K videos (around 2TB) per year.

Some images are private, only for my wife or for myself, some should be shared. I tried having a 'shared' folder (synced using private OwnCloud), and then manually selecting which photos and videos should be shared. But that is too time consuming and therefor fails.

1. What setup do you use to manage and share large amounts of shared photos/videos?

2. How do you backup and prevent duplicate data?