When purchasing a multimedia projector there is so much to consider. What, if any, computer will you use with the projector? Do you need the projector to travel? How important is weight and price? What about additional features like a remote control, networking abilities, and PC-free presenting?

But there is another side of the coin as well, choosing the projector screen. And there are just as many questions associated with screen choice. Will the screen be mounted? Will it be fixed? Does it need toretract? What type of fabric is best? What is the standard viewing arrangement?

And once you have answered all of your projector and screen questions, there is still another area — where the projector and screen meet, that gray area of how they two work together. This is a tricky situation because both the projector and the screen have influence on each other. Following are two items for consideration directly related to this middle ground: throw distance and screen size.

Throw Distance

Throw distance refers to the distance between the projector and the screen. It is the distance the image is "thrown". Throw distance is the foundation for determining the screen size, and it also helps determine if you need to use an additional lens.

In normal circumstances, most presenters do not need to use an additional lens, but depending upon the throw distance of the projector configuration, you may need a long or short throw lens.

Long throw lens: The farther you move a projector away from the screen, the larger the image is projected. If you have flexibility in positioning your projector, this may never be a concern. However, if you need to position a projector at the back of the room, you may need a long throw lens to reduce the image size to fit the screen.

Short throw lens: This type of lens is the opposite of a long throw lens. A short throw lens is used when the projector needs to be positioned

Screen Size

Screen size is just that, the size of the projector screen, and it is directly related to the viewing distance. While there are various formulas for determining the correct screen size in relation to viewing distance, most schools of thought say the ideal viewing distance is 1.5 times the width of the screen. So, if your room configuration calls for the audience to view the screen from a distance of twelve feet, the screen should logically be eight feet wide.

This is a good general rule, but it is not completely accurate. Screen size is also related to the type of material that is projected. For example, if you are projecting very fine text — as opposed to simple graphic images — you may want to consider a larger screen size. Of course, screen size relative to viewing distance is also a matter of taste. Just as some people like to place their couch quite close to a big-screen TV, and others prefer a smaller screen placed a distance away in the corner of the room, some presentation situations call for bending the screen size rules. The 1.5:1 / viewing distance:screen size rule is a basis from which to begin.
Additionally, one should consider the light source when choosing screen size.

Many people make the mistake of trying to push a projector's capabilities by trying to create the largest possible screen size. This is not the best idea. No matter what projector you use, the smaller the screen size (image size) or the closer the projector is placed to the screen, the brighter the picture. Consider that the light source only contains a fixed amount of light. So, if you spread that light over a larger area, the picture looks less bright than it does when focused on a smaller area. Once you determine your screen size, this information can help determine where to position the projector to adequately fill the screen.