I have a difficult time in getting Photo-Focus to work myself.
I can see the blip page on the book when I'm looking at my un-cut lengthy toenails but the blip disappears when my eyes wander up to the book. This is probably a practise thing.
One thing I wonder about is, is the Photo Focus like crossing your eyes though? It certainly seems different and is more of a strain on the eyes though the blip appears.
Martin