Shoppers should screen claims about monitor size


August 23, 1993|By MICHAEL J. HIMOWITZ

The outraged letter from Bob was typical of several I've received lately:

"I just bought a computer with a 14-inch monitor. When I got it home, I thought the screen looked a little small. So I measured it, and it was only 12 1/2 inches across. I thought maybe someone had made a mistake, so I called the store, and they said that's what you get when you buy a 14-inch monitor. Am I getting ripped off, or what?"

Welcome to the fuzzy world of cathode ray tubes, an anomaly in a computer universe defined by precise specifications for just about everything else.

If you haven't noticed the fine print in ads for monitors and television sets, the measurement they use is the diagonal distance from the top left to the bottom right corner of the screen.

Or bottom left to top right, if you're left-handed.

There's a good reason for this: the diagonal measurement is always bigger than the horizontal or vertical measurement. It sounds better to advertise a 14-inch monitor than, say, an 11.2-by-8.4-inch monitor -- the real dimensions of a 14-inch screen.

A brief aside for you math majors out there. The proportion of a standard TV or computer screen is four to three. No matter what the actual size, the screen is always four units wide by three units high, which means the diagonal measurement is always five units. It's one of those neat little right triangles that comes out evenly.

To figure out the real dimensions of any screen, divide the diagonal measurement by five, then multiply the result by four to get the horizontal measurement and by three to get the vertical measurement. If that's too much trouble, get a ruler. It'll come out the same either way.

That exhausts my 10th grade geometry. Now to Bob's question. Why does his 14-inch screen measure only 12 1/2 inches diagonally? Actually, the cathode ray tube probably does measure 14 inches. But the manufacturer covered a portion of the edge of the screen with the case of the monitor. How much area any monitor loses depends on the individual unit. But you'll inevitably see less than 14 inches.

Individual units differ

The 14-inch monitor on my computer, which is about two years old, also gives me only 12 1/2 inches of visible screen. My kids' monitor, nominally the same size, provides slightly more than 13 inches of glass.

To make things even fuzzier for buyers, monitor makers often design their electron gun circuitry to cover somewhat less than the whole screen, leaving a blank border. There are a couple of reasons for this. First, the maker of the cathode ray tube may not know how much of the surface will be covered by the monitor case, so he'll play it safe. Also, the curvature of the screen on some monitors starts to produce real distortion when the beam gets too close to the edge.

These little adjustments can rob you of a significant viewing area. On my monitor, the actual image on the screen measures only 11 3/4 inches diagonally, a full 2 1/4 inches less than the monitor's advertised measurement. But on my kids' monitor, a newer design, the image fills the entire 13-inch visible portion of the screen.

The arithmetic shows that my monitor gives me a paltry 64 square inches of viewing area, while the kids get 83 square inches. That means their monitor provides a 30 percent larger image than mine, although they're both classified as 14-inch screens.

In the days when most programs for IBM-compatibles used the standard, character-based screen, this wasn't a problem. The fixed character matrix -- 25 lines of 80 characters -- provided type that was large enough to read even if the monitor maker cheated a little.

More readable screen

But in graphics-based environments such as Microsoft Windows, there's no standard character size. In practice, the characters in Windows are smaller and harder to read than they are in DOS programs. In this environment, a larger display area makes a more readable screen.

Also, Windows allows you to run several programs simultaneously. The more space you have to display these programs, the easier it is to work with them.

My advice to buyers like Bob is to shop carefully for a monitor, or if you're buying a complete system, look for one that comes with a monitor that provides a comfortably large display area. Price doesn't necessarily guarantee the maximum display. My kids' monitor, which produces a superb image, was part of an inexpensive system I picked up at a computer show.

Computer makers are doing their bit to help, too. Realizing that the standard 14-inch screen may not be big enough, many manufacturers are now packaging 15-inch monitors with their systems, some as standard equipment, some as options for a few dollars more.

They provide a 16 percent larger viewing area than their 14-inch cousins, and an image that is at least marginally readable if you decide to display your programs at anything higher than standard VGA resolution.

If you're planning on doing a lot of desktop publishing, graphics work, or virtually anything that will keep you in the Windows environment for hours at a stretch, consider a 17-inch monitor. At $700 to $1,000, these cost about twice as much as their smaller cousins, and they occupy a lot more desktop real estate. But they can save a lot of wear and tear on your eyes, enough to make the premium seem like a small price.

Scary Product of the Month: A California outfit called PSI Integration is teaming up with the Sprint long-distance network on a program called FAXcilitate. It lets you send thousands of faxes from your Macintosh computer with a single local phone call.

I don't know about you, but I think Americans get enough junk fax as it is. There ought to be a law about this kind of thing. Call your congressman. Better yet, fax him.

(Michael J. Himowitz is a columnist for The Baltimore Sun.)

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