According to projectorcentral, "The L500's lens is fixed, and therefore so is the throw angle. It is set so that the centerline of the lens intersects the image at a point about 12% of the picture height above the bottom edge of the image when table mounted, or 12% below the top edge of the image when ceiling mounted." I'm no idiot but it took me a while to figure this out. If my screen width is 52' wide and the top of the screen is 8' with 9' ceilings I will need a mount about 20" long. 12% x 52"= 6.25 + 12" drop from the ceiling. IS THE SCIENCE THIS EXACT IF I DON'T WANT TO USE KEYSTONE CORRECTION? This seems like a very long drop. What have other panny users experienced? Thanks for any help.