To get the big-screen effect, a typical projector needs to be positioned a fair distance from the wall. In cramped living quarters, that often requires perching the projector on a high shelf or mounting it to the ceiling—a real eyesore and a cabling nightmare. In cavernous great rooms, projectors pose a different problem: Anyone who crosses the room winds up casting a shadow over the image and is likely to be blinded by the projector’s beam.
“Short-throw” models can create a surprisingly large image when placed just a few feet—or, in the case of ultra-short-throw versions, a few inches—from a wall, with no compromise in video quality.
Read more: http://www.wsj.com/articles/big-screens-for-small-spaces-the-magic-of-a-short-throw-projector-1469124707