The normal range projector has a long projector’s throw distance and it is placed approximately 3-5 meters from the projection screen or wall. A disadvantage of normal range projection is that the presenter, standing in front of the screen, must extend his or her arm with or without a stylus to avoid casting a shadow. This is not a disadvantage of the other 2 projectors discussed below, which cast an image from above and just in front of the Interactive Whiteboard surface, removing the presenter from the beam's path.
A projector with a special wide angle len that is mounted much closer to the Interactive Whiteboard surface and projects down at an angle of 45 degrees. These vastly reduce the shadow effects of traditional front-projection systems and eliminates the problem where the user or presenter sees the projector beam.
Ultra Short throw projectors are used in applications where the distance to the projection screen must be minimized. Different models of this are able to project onto a screen at short distance as 0.4 feet. These projectors come in both 4:3 and 16:9 aspect ratios and may include support for networking.
The first benefit of buying a Short and Ultra throw projectors also happens to be one of the most obvious: less room between the projector and the screen means less room for people to get in the way.
Every projecting situation does not require a short throw projector. But there are some situations in which a short throw or ultra short projector is the perfect solution. Small learning spaces, conference rooms where detailed documents are shared, trade shows where a big image gets big attention, and in home theaters with projector placement limitations, schools, churches, trade-show booths and home theater rooms.