Originally Posted by noah katz
It is a bit ambiguous (should have said both left and right edges of pj equidistant from screen), but it doesn't say anything about centering; it means what Mark said, to avoid keystoning.
I don't think measuring distances is the best way to get the yaw correct. There's too many ways to screw that up. (You'd have to measure exactly
perpendicular to the screen, and without a 15+ foot long carpenter's square, that's basically impossible. Or let's say you measured the distances from the left edge of the screen to the left edge of the PJ, and same for right, and got them exactly equal, that still doesn't tell you anything useful because the PJ could be both shifted left and yawed left, or both shifted right and yawed right, and the distances could still be exactly the same.)
And why bother, when it's easy to eyeball the projected image and adjust the yaw based on that.
What I'd like to find is a general (not JVC-specific) howto for projector alignment. Pictures showing problem alignments, and corrections needed. "If your image looks like this, rotate the PJ this way..." It can be pretty confusing when both yaw & roll are misaligned.
Anybody ever seen something like this? It certainly would have helped me set up my 4810 last year.