The videoprojectors are divided into different categories according to their use. They simple edition, ST (short throw), UST (ultra short throw) Below we give you a link that you can find the right distances to set the projector from the writing board, something very important for proper visibility and focus of the projector. The options you have are in meters or inches, size 4:3 or 16:9 display, placing the projector ceiling or floor. http://www.benq.com/microsite/projector/throwratiocalculator/ http://www.visualapex.com/projector-calculator/screen-size.asp