With hundreds of portable projectors on the market, the would-be buyer faces an overwhelming array of features and options. The following brief guide can help you choose the projector that's right for your needs

The key features to consider are the following:

Resolution: The resolution is simply the number of pixels projected onto the screen. The more pixels you have, the more closely they are packed together, providing a smoother appearance to your image. The resolution is specified in terms of the number of horizontal and vertical pixels in the image. The most common configurations have names like VGA and XGA that serve as a shorthand way of referring to these the pixel resolution. They are:

VGA (640X480 pixels)

SVGA (800x600 pixels) Standard.

XGA (1024x768 pixels) High resolution, currenly the most common in laptops.

SXGA (1280x1024) The most common resolutions for CAD, GIS and other special graphic applications.

UXGA (1600x1280) Large format. The best choice is to purchase a projector that matches the number of screen pixels on the laptop computer that will be driving the projector.

Luminosity: Luminosity is the quantity of light projected onto the screen (i.e., the brightness). It is measured in terms of an international ANSI standard called lumens. The higher the luminosity, the brighter and more visible the projected image. The greater the distance between the projector and the screen, the more lumens you need for a clear image. To project a distance of 20 feet (unless the room is very dark) typically requires a projector with at least 1000 lumens.

Dimensions and weight: If most of your presentations will be made on the road, you'll want a small, lightweight projector. Portable projectors typically weigh between 6 and 10 pounds, and the so-called "ultra portables" between 2 and 6 pounds. Look for a projector that includes a good, sturdy case to keep it safe when traveling.

The Room: The qualities of the room are crucial to a clearly projected image. A large room requires a projector with more lumens to reach the screen with sufficient brightness. Equally important is the lighting in the room itself. How dark can you make it? How much light will your audience need (for example, will they be taking notes, or simply watching the presentation passively?) Before the audience arrives, experiment with the lighting in the room by opening and closing blinds and turning on and off various sets of lights, so that you'll know exactly what to do when it comes time to darken the room for your presentation.

Computer connections Make sure that your projector has connectors that are compatible with the laptop computer you plan to use with it. These are typically expressed in terms like VGA, S-Video, RCA, and sometimes by the number of pins on the interface cables (15-pin, etc.) This information is available in the "full specifications" part of the projector information.

Portable Projectors have other specifications in addition to these, such as Contrast Ratio, Aspect Ratio, and many other features, but the key parameters described above are the fundamentals that will help you make the right choice.