It's FAT32 file system. Some of the photos recovered have what look like the original numbers on them, original is eg 'P1046572.jpg', the recovered files with no preview have '_1046572.jpg'. Some have previews and those have numbers like '[000597].jpg'. The latter are full files and I can open them with Photoshop.
Looking at the files in Recuva, some say 'State: Excellent, Comment: No overwritten clusters detected'.
But I still can't open them and they don't generate a preview.
And Recuva just crashed on trying to save to a new folder