Resolution refers to the number of dots of light that appear on a screen or a projection to make up a projected image, and measures the amount of detail that can be seen in an image. Take care to note the "native" resolution of the digital projectors you are interested in - while a projector may be able to work with several different resolutions, there is one native resolution at which it works best.

Choosing the right resolution for your projector is as easy as knowing the resolution of your computer. If you plan on upgrading your PC after getting a new projector, you're best off buying a projector with a fairly high resolution that will match newer laptops.

Your presentation won't come to a screeching halt if the resolution on your notebook and projector differ. Virtually all models can accept higher or lower resolution images than their native resolution via interpolation, which either expands or compresses the pixels that compose the image. However, you can expect lower quality images when using interpolation.

The two most common resolutions right now are SVGA (800x600) and XGA (1024x768). Higher resolutions like SXGA (1,280x1,024) will dramatically increase the price you should expect to pay. VGA (640x480) is no longer an acceptable resolution, and you would be hard-pressed to find modern projectors that support it.

Digital projector lenses
Zoom lenses are nearly standard on today's projectors. A zoom lens lets you project a larger or smaller image to compensate for the distance between your projector and the screen.

The f-number of the lens is a measure of how much light gets through the lens to the screen. Be sure to check how much a lens' f-number (the smaller the number, the more light) changes at different zoom settings. If the change is minimal your image will remain uniformly bright regardless of lens position.

Some lenses are now manufactured using lightweight plastics. If weight is not an issue, try to find a machine with an all-glass lens. Glass is the optimal filter for projecting images and will give you a clearer picture. However, glass lenses do make a projector heavier, so pick plastic if you are going to be on the road a lot.

Optional lenses are also available through some manufacturers and resellers. If your conference room machine will be called upon to project at different positions, angles, and varying room brightness, you should ask about interchangeable lenses.