Backup
If i backed-up my old iphone to my computer, where did all of my photos go to?
iPhone 6, iOS 10
What do you mean where did they go? They should still be on your phone if you didn't delete them. As for the backup, if it still exists on your computer and hasn't been overwritten by a later backup, then the photos that were in the camera roll when you backed up are in the backup. Restore it to your phone to recover them.