Nightwalking uses a near-point gaze to develop "second-sight" or the processing of distant-point information with the periphery of your foveal and macular visual fields. It works for walking around...try staring only at your thumb in front of you while you walk around for a few minutes. I use this as a demonstration in the courses I teach.
PhotoFocus is uses a far-point gaze to develop "second-sight" or nonconscious processing of near-point information on the page. When you do, your eyes relax, your pupils dilate, your eyes take in more information and the brain/body changes state.
I have also found that convergence creates more eye-strain and pupil constriction for most people.
The clarity and 3-dimensionality comes when the focal plane is on the page in front of you. Yes you can get THAT effect with crossed or divergent gaze. I prefer to get it with divergence.
