You're thinking of buying an LCD projector. Perhaps you've had bad experiences renting or getting support from hotel audiovisual departments, or maybe the cost, which has fallen from the mid-teens to $4,000 to $8,000 for a decent machine, has finally made ownership possible. How do you go about it? What should you look for?

The first rule for purchasing a portable LCD projector is to match the projector's native resolution to the computer you are going to be using. Unlike CRT-based projectors (those three-gun or RGB-type units) that adjust to various computer resolutions, the LCD panel inside the projector has one specific resolution at which it works best. This is called the native resolution.

If several presenters need to use the same projector, but their computers have different resolutions, anticipate problems. First, test the computer presentations (without an audience) to see if your projector can handle the conversions. If the result is disappointing, consider an external converter, but be warned; good interfaces can cost thousands of dollars.

Bright Lights, Big Picture The second rule is to buy as bright a projector as you can afford (and can comfortably carry). Brightness is measured in ANSI lumens and portable projects on the market range from 400 to 1,200 lumens. Think in terms of the size of the audience and how large the screen must be for the back row to read the difference between a B, a 3, an 8, and an H, especially with finer text, such as on a spreadsheet. Two rules of thumb apply here:

1. The image height should be 1/6 to 1/8 of the distance between the screen and the farthest viewer.

2. The projector should have enough brightness to provide 12 to 20 ANSI lumens per square foot area of the screen.

Using these formulae, the largest screen a 500 ANSI lumen projector can illuminate is five-feet by seven-feet, which is visible 30 to 40 feet away.

Get Your Show on the Road So, your projector has finally arrived. You're ready to take it on the road. What should you expect?

Well, to start, do not expect to be warmly embraced by the hotel's AV department. Projector rentals can be a significant revenue source for these departments. But while they'd like to discourage you, more and more, BYOE (bring your own equipment) is becoming commonplace.

Now that you have the projector, don't try to stuff it into an old suitcase on the way to the meeting. Samsonite (www.samsonite.com), Porter Case (www.portercase.com), and Tenba (www.tenba.com) all make excellent ATA-approved travel cases. Make sure you have the necessary adapters, cables, extension cords, gender changers, and so on. Also, carry at least one spare lamp; preferably two. Do not count on the hotel AV department.

Practice using your equipment.This may sound obvious, but the greatest horror stories of hotel AV departments come from the guests who show up with no clue how to set it up, adjust it, troubleshoot, or even turn on their projector.

So, if you're considering buying your own projector, do your homework, become familiar with your equipment, carry spare parts and adapters, and anticipate the complications of matching with other equipment. This is where peace of mind comes from.