I've done a good bit of reading old threads and such, and I can't seem to easily find a situation matching mine. I am running out of space on my aging 5S, so I'm looking at iCloud to solve this problem for me. My phone has been acting up, missing messages, etc. and I can't be having those kinds of issues. I've been deleting photos and apps piecemeal over the last several months, and it's just not helping anymore. Thankfully, all the photos I want to keep are on my Mac. I am currently running 10.10.2 on my Mac. I plan on upgrading my iCloud storage, then upgrading to 10.10.3 so I can turn the iCloud Photo Library on from there. All of the pictures I want to keep are already on my Mac, but I still have several photos on my phone. After I set my Mac up for iCloud Photo Library, what happens to the photos that are already on the iPhone when I flip the switch for that too? Are they deleted from the phone automatically? I don't want any duplicates. How smart is the process when switching it all on? What happens when you turn on the Photo Library for the iPhone first instead? Would my Mac then sync with the photos currently on my phone instead of the larger library of photos overall?