I bet it worked! Brilliant Idea.
Hopefully others will read your post and try it themselves. The creation of a simple tool for learning. Looking through the book is the essance. Might be more than 6 inches.
If your eyes felt relaxed as they do when you look at stereograms and you had an awareness of the 4 sides of the book while you were photofocusing it's unlikely you were looking at it cross-eyed. If you were you would have had sore eyes in no time.
Alex
