I recently revised my High Power Screen Gain Calculator (see separate thread in this forum) to compute screen gain simultaneously for the left side, center, and right side of the screen. This reveals not only gain but also brightness uniformity for a given input configuration. While testing the new version of the calculator, I learned some things about brightness uniformity that I think may be of interest to current HP owners and those considering the HP, as follows.
1. For a center seat, the HP provides near perfect brightness uniformity, even for very wide screens.
2. For some configurations, the HP provides slightly higher gain at the right and left sides of the screen than at the center! This can help correct any edge brightness loss of the PJ. Note that this behavior is opposite that of angular reflective gain screens, which exhibit lower gain at the sides, IIRC.
3. For off-center seating, the brightness uniformity is highly sensitive to the distance of the PJ lens from the screen, near perfect uniformity being achieved when the PJ lens is about the same distance from the screen as the off-center seating. A PJ position somewhat to the rear of the off-center seating makes the side of the screen brighter on the same side as the off-center seating. A PJ position somewhat to the front of the off-center seating makes the side of the screen brighter on the opposite side from the off-center seating.
I invite those of you who would like to evaluate your own HT configuration to play with my new (Ver. 2.0) HP screen gain calculator. It's free, of course, and very easy to use.