While testing Lightroom, I’ve decided to set my iCloud Photo Library to Optimize Storage. That way, it won’t take up very much space on my devices because it will dynamically decide which photos to keep at full resolution, while still retaining the benefits of automatically syncing photos between my iPhone and iPad in the background.
Optimize Storage, if done right, is actually what I’d like most from a cloud photo service. I want the benefit of having my pictures within easy reach, but I don’t want to necessarily store everything at full resolution locally. What would make the most sense to me would be to have thumbnails of my images that are sized exactly to the device screen, which means 2732×2048 for the 12.9” iPad Pro and 1920×1080 for my iPhone 6S Plus.
This is the way I understand Photos on OS X and Lightroom to work. They don’t just display a small thumbnail and a medium thumbnail, they generate these extra files in advance to speed up the experience of browsing through a large library of photos. I know that iOS generates the tiny thumbnails that are seen in the Years, Collections, and Moments views, but I’d love to see Optimize Storage also generate fullscreen previews for every single photo in my library. This would let me view any photo in my library regardless of online status, but it wouldn’t take nearly the same amount of space as an actual 6000×4000 (24 Megapixel) shot.