Originally Posted by bubbawilly
So, can anyone tell from the manual what the actual offset is?
The manual states the offset is H' = L * tan(6.52), where L is the distance from the pj to screen.
If you want offset relative to screen height then it's relative to the zoom, since the right triangle with the hypotenuse from the pj lens to the top of the screen is the same size whether you have full zoom or not.
Using the manual formula for H' and projector central's HD72 screen calculator, I get these numbers for a 10' throw:
Offset= 120" * tan(6.52) = 13.7"
At a 10' throw min zoom results in a 36" high screen, max zoom results in a 43" high screen.
13.7"/36" = 38% of screen height offset for min zoom
13.7"/43" = 32% of screen height offset for max zoom
SGinAZ is correct that it has an 11.4% offset *relative to throw distance*. As he mentions this means for every 100" from screen to pj, offset increases by 11.4".