How do I download originals for a certain album in Photos when using “Optimize Device Storage” on iPad?
There are actually multiple levels of download. Even when you view an image, a device-optimized version is retrieved. Only when you Edit or Share a photo is it fully downloaded from iCloud (possibly when you zoom in all the way, also).

With that being said, you can’t bulk-Edit; however, you can bulk-Share. Here are the steps that worked for me:


Go into the album you wish to download locally.
Tap Select.
Tap Select All.
Tap the Share icon in the bottom-left hand corner.
Select Email.
Wait for the Preparing progress indicator to complete. This may take a while depending on how large your album is and on the speed of your connection.
When your email is ready, Cancel out of it.


Remember that these photos are eligible for purging if your device becomes low on storage.

Note: I tried this on a relatively small album (20 photos and videos). I don’t know if your iPhone might crash attempting to share 500 photos at once.

If you choose to Download and Keep Originals, I believe your iPhone does that while your device is locked, on Wi-Fi, and has sufficient charge. It might help to have Photos as the foreground app when locking the iPhone.