Buyers' Guide to Monitors

Key Features

CRT Monitors

Tube type: Shadow-mask displays employ a metal sheet perforated with small holes to focus an electron beam that illuminates phosphors on the inside of the tube. These monitors usually have a slightly curved face, though some flat-screen models are available. Shadow-mask monitors are generally the monitor of choice for use with drawing applications such as CAD because they tend to render accurate straight lines.

Other CRT monitors have aperture-grille tubes, which send their electron beams through an array of thin vertical wires. The grille is supported by one or two wires that cause a faint line to appear in the bottom and top thirds of a white screen. Many aperture-grille models, which tend to cost more than shadow-mask displays, have a flat face. They typically render bright images, making them ideal for people who work with graphics. Though they cost more, flat-faced models repay the investment, because they present a clear, undistorted image and reduced glare from ambient light.

Dot pitch: Despite their prominence in advertisements, dot pitch and stripe pitch aren't the best indicators of a monitor's image quality. Dot pitch (or diagonal dot pitch) is the distance between two like-colored phosphors on a shadow-mask CRT. For aperture-grille tubes, vendors cite stripe pitch--the horizontal distance between two like-colored stripes of phosphor. For shadow-mask displays, ads may also list horizontal dot pitch; this is the distance between two columns of dots of the same color--a lower number than for diagonal dot pitch, but one meant to be more comparable to the stripe pitch figure. Correlating these measurements with actual performance is difficult, but your eyes provide the best gauge of image quality: Observe how the kinds of documents and pictures you work with look.

Resolution and refresh rate: A 17-inch CRT monitor with a listed maximum resolution of 1600 by 1200 may seem high-end, but if it can display that resolution only at a refresh rate of 60 Hz, you shouldn't be impressed. A monitor's refresh rate indicates the number of times per second the screen gets redrawn. At any refresh rate lower than 70 Hz, your eye will likely detect the screen flickering.

Even if the monitor supports a high refresh rate, text and icons must be large enough for comfortable viewing. Text on a 17-inch monitor at 1600 by 1200 resolution will be small for all but the sharpest eyes, though most people could work at that resolution on a 21-inch model.

LCD Monitors

Native resolution: Because an LCD uses a matrix of cells to display its image, it has a fixed (or native) resolution at which it looks best. A 15-inch LCD has a native resolution of 1024 by 768, while a 17- or 18-inch model will look its best at 1280 by 1024. If you set the monitor to a lower resolution, the image will blur, because the display will use only a portion of the pixels it contains and will scale up the resulting image to fill the screen.

Though scaling technologies have improved recently, you're likely to be disappointed with the results. Text looks jagged at nonnative resolutions, so an LCD is a good choice if you tend to use just one resolution for all applications.

Viewing angle: An LCD's viewing angle (measured in degrees) indicates how far you can move to the sides or above or below the center of the display before the image begins to darken or blur. An angle of 160 degrees is advisable; a narrower angle may make the screen look as if you were seeing it through a tunnel. Vendors measure viewing angles in different ways, so those specs are similarly meaningless, except within brands. Whatever the spec reads, viewing angle is vital, so view before you buy.

Many LCDs have stands that can adjust or swivel sideways; this can help compensate for a relatively narrow viewing angle.

Contrast ratio: This term refers to the difference in light intensity between the brightest white and the darkest black that an LCD can produce. Look for a contrast ratio of 300:1 or better--with anything lower, colors may wash out when you turn up the brightness and may disappear when you turn it down.

Digital vs. analog: If your PC has a graphics card with digital video-out, choose a digital LCD. Because the image won't have to be converted from analog to digital and back again, it will be clearer. Even if your system doesn't have a DVI port, a digital LCD makes sense, since most also have an analog connection. Digital inputs tend to be found on relatively high-end models, but they are becoming increasingly prevalent at all price levels.

Both CRTs and LCDs

Size and depth: Bear in mind the size of your workspace when deciding on the type of monitor to buy. The average 17-inch CRT monitor can measure almost 17 inches deep and weigh 40 pounds or more, while an average 17-inch LCD takes up half the space, with a depth of 8 inches and a weight of 17 pounds.