As you navigate into a photo collection, you’ll see a preview of the photo pop up on the right side of the Theater’s on-screen interface, under which you’ll also see the photos size in megabytes. (It would have made more sense to offer additional metadata about the photo here, such as date taken, rather than repeating the file name you can already see selected on the left.) Also note the handy counter down in the lower left corner, here showing 71/101, to let you know where you’re at in long file lists.