The screen measures 140" diagonally. The projector is an Epson 3020. According to Epson's Image size calculator, the throw distance is 13' 7" to 22' 1". My media room is 20' x 18'. The screen is mounted to the 18' wall. I can mount the projector from the ceiling about 18' from the screen at maximum because of heating vent, etc. I am wondering what would be the optimal distance from the screen to mount the projector (taken into consideration zoom factor, picture quality, brightness in 2D and 3D, etc.)?