Because it doesn't. Doesn't matter, it can be ceiling mounted just fine. Read the review or the owner's manual for offset information. If a projector does not have a 'known' offset or if the offset doesn't work with the calculator, or the projector has lens shift, then the projector defaults to the 'middle' of the screen. This is NOT accurate and you must read the manual or reviews to determine the offset. The 2030 has -8% offset. So, when ceiling mounted, the center of the lens must be 8% of the image height below the top of the screen. So, if the screen is 50" tall, the center of the lens must be 4" below the top of the screen. If the screen is 8" from the ceiling, the center of the lens would need to be 12" from the ceiling. This is very unusual for projectors. Most need to be several inches (or more) above the top of the screen.