Jumat, 07 November 2008

buy monitor



Introduction

Monitor Buying Guide graphic

Everyone needs a good monitor to get the most out of a PC. But which monitor you need depends on several factors--what applications you use, how much room you have on your desk, how much space you need on a virtual desktop, and of course how much you want to spend. From standard-issue 19-inchers to 24-inch monsters, here's how to sort out what you need.

The Big Picture
How is an LCD different from yesterday's CRT? We'll explain the advantages of LCDs, and tell you which monitors work best for what you do. more

The Specs Explained
We'll help you sort through the litany of options for LCD monitors. more

Monitor Shopping Tips
Ready to buy? Here's what to look for and what to avoid. more


The Big Picture

If you've replaced an old PC in the last few years, you may have kept your old monitor to use with the new machine. That's okay if it's in good shape--most monitors have a life span of about five years--but if it's a worn-out 15-inch CRT that produces barely legible text at 800 by 600 pixels, you're hobbling your productivity.

Most monitor manufacturers offer entry-level LCD models that combine very low prices with pared-down features. These monitors work well enough for Web surfing, e-mail, and other office tasks--as long as they provide adequate resolution and screen adjustment controls for brightness, color, and other settings. Midrange and professional lines often provide better image quality and extensive features, such as superior image-adjusting controls, USB ports (make sure you get a monitor with USB 2.0 ports--some models with USB 1.1 hubs are still on the market), a larger set of ergonomic options (such as height adjustment), and higher resolutions. Some professional-level monitors include asset control--to help IS managers keep track of their company's property via a LAN--and hardware calibration, which adjusts the monitor and/or graphics card to ensure precise hues. (Third-party calibration packages are also available.)
CRT vs. LCD

Historically, graphics professionals have preferred CRT monitors because they support a greater range of resolutions (including very high resolutions) and show truer colors and greater nuance in color. However, manufacturers ceased making the aperture-grille models--generally agreed to be the top-performing type of CRT for photos and general graphics work--in 2005. Many pros now use high-end LCDs, which approach the color quality of CRTs yet consume half as much power or less. The development of color-calibrating hardware and software specifically designed for LCDs has helped persuade many professionals to make the switch to flat panels. Promises of improvements in black level (perfect black--which is traditionally somewhat soft or grayed in LCDs) and a wider color gamut should make this transition still easier in the near future. Another bonus: The greater brightness of LCDs also frees graphics pros from the confines of their darkened studios.

People who work mostly with text have always gravitated toward LCDs because pixels on an LCD have well-defined edges, resulting in sharply focused letters. Some gamers still prefer CRTs because LCDs redraw their screens more slowly, which can produce blurring and motion artifacts in moving images. However, response time--the spec that governs image motion in LCDs--continues to drop, minimizing the ill effects. Modern LCDs can refresh quickly enough to make them game-worthy for most users.

Budget constrictions may still drive some buyers to CRTs, which usually cost less than LCDs that have a comparably sized viewable screen area. As LCD prices fall, though, more users and companies are going for the slim form and low power usage of the LCD. So from this point on, this guide will discuss LCDs only.
Key Features

Native resolution: Because an LCD uses a matrix of pixels to display its image, it has a fixed (or native) resolution at which the display looks best. A 15-inch LCD has a native resolution of 1024 by 768, while most 17-, 18-, or 19-inch models use a 1280 by 1024 native resolution. Wide-screen 23- and 24-inch wide-screen models usually have a native resolution of 1920 by 1200, and 30-inch wide-screens have a resolution of 2560 by 1600. If you are using Windows XP or earlier and set the monitor to a lower-than-native resolution--to upsize very small text, for instance--the image will almost certainly be less defined, because the display will use only a portion of the pixels it contains and will scale up the resulting image to fill the screen. Keep in mind that you can never exceed the native resolution of an LCD monitor. So, for example, you will not be able to display 1600-by-1200 resolution on an LCD with a native resolution of 1280 by 1024.

Though scaling technologies have improved in recent years, you're still likely to be disappointed with their results. On Windows XP and earlier, text most readily shows pronounced jaggedness at nonnative resolutions. Windows Vista may reduce this effect with its vector graphics, but it's still advisable to use a monitor at its native resolution. So a particular LCD is a good choice if its native resolution is one you are comfortable using for all applications. In the PC World Test Center, all monitors are tested at native resolution.

Aspect ratio: Most LCDs have a screen aspect ratio of about 3:4, much like a regular-format TV. However, wide-screen monitors have an aspect ratio closer to the 16:9 aspect ratio of HDTVs. The wide-screen format becomes useful for working in large spreadsheets or in programs that contain many toolbars or palettes. It's appealing for watching DVDs as well, although the image quality may not be as good as on a TV. Many users see a wide-screen monitor as an upgrade from smaller dual monitors. A dual-monitor setup is usually the less expensive proposition.

One important thing to keep in mind: The screen size is measured diagonally, and the area of a wide-screen monitor's display is smaller than that of a regular-format display of the same size. In other words, a 21-inch wide-screen monitor shows about as many pixels as you'd expect from a regular-format 19-inch monitor. In the days of CRT monitors, vendors would state a tube size, say 21-inch, but the diagonal of the viewable screen would be from one to two inches less. With LCDs, the stated diagonal is always the true measurement from the viewable screen.

Viewing angle: Measured in degrees, an LCD's viewing angle indicates how far you can move to the side (or above, or below) from the center of the display before the image quality deteriorates to unacceptable levels. No matter what size monitor you use, a wide viewing angle becomes increasingly important the more you care about getting accurate, consistent colors for design work or for tweaking digital photos. Each vendor determines its own criteria for this, as no industry-standard method has been established for measuring viewing angle. As a result, the numbers may not be comparable from one vendor to another, but they can indicate relative performance among models from the same company.

The best way to judge viewing angle is to see the monitor for yourself, but you can eliminate some models from consideration if even their vendor-reported viewing angles are below a certain value. The larger the monitor, the more important a wide viewing angle is. On monitors measuring 17 inches or more, the edge of the screen is at a greater angle to someone sitting directly in front of its center, and people are more likely to be able to share the monitor when working or giving a group presentation. A viewing angle of at least 150 degrees is advisable for these monitors.

The choice of panel technology affects the viewable angle. Some LCDs use twisted nematic panels, which have small viewing angles. On a TN screen, brightness drops and colors change as you move to the side or up and down. This can mean that your work will look different if you adjust your chair or your posture. It also makes it difficult to share your work with someone who sits next to you (although a physical swivel adjustment can help with this). A few years ago, TN panels appeared to be on their way out, but recent interest in TN's fast pixel-response times has brought more new models to the market. Other panel types, such as in-plane switching, multidomain vertical alignment, and patterned vertical alignment, have wider angles of view than TN panels can offer.

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 400:1 or better--with anything lower, colors may wash out when you turn up the brightness and may disappear when you turn it down. However, higher is only better up to a point. Contrast ratios over 600:1 are unlikely to provide any advantage, and monitor vendors are likely using "fuzzy math" to calculate those values, anyway.

PC World Test Center evaluations of 15 LCD units in May 2003 showed that in some cases, actual contrast ratios were below the vendors' specifications--by as much as 50 percent. Most companies actually erred in the opposite direction, with a published contrast ratio that fell below our measured result--something that most people probably would not mind. But since shoppers have no way to tell if the manufacturer has overstated or understated contrast ratio, the specification is essentially useless for comparison purposes. When shopping for an LCD, your best bets are to check independent reviews such as those in PC World's Reviews and Rankings section and to trust your own eyes.

Brightness: Expressed as candelas per square meter (cd/m2) or nits, this specification measures the greatest amount of light that comes from a screen displaying pure white. Nearly all LCDs have a brightness level of 250cd/m2 or greater, which should be more than sufficient. (In comparison, CRT monitors typically average about 100 cd/m2--though you might see some high-brightness CRTs.) Vendors usually set the brightness level to maximum on new monitors to impress customers. High brightness can be eye-catching for video and graphics, but it can be uncomfortable over time, particularly for text viewing--and it may cause certain photographic nuances to wash out. After using the monitor for a while, you will likely want to turn the brightness down a bit to spare your eyes. Many monitors offer screen modes that change the brightness (and sometimes color and other characteristics) to make certain types of content look best.

Digital versus analog: If you have a graphics card with digital video-out--and if your computer is less than two years old, you probably do--choose an LCD that has DVI digital input. The image won't have to convert from analog to digital and back again, so it will be clearer. Even if you don't have a DVI port on your system, choosing a digital LCD makes sense, because your next desktop PC probably will have a DVI port--and most digital-capable monitors also have a VGA (analog) connection. Digital inputs tend to be found on more-expensive LCDs. Very few notebook PCs come with digital outputs for external monitors. However, some notebooks can gain a DVI connection when they attach to a docking station or port replicator. (Note that there are two types of DVI connections found on typical LCD monitors: DVI-D and DVI-I. DVI-D is a digital-only port; DVD-I can accept either an analog or a digital input. You'll need a special connector to hook up to your PC's VGA analog port, however.) DVI-I obviously provides greater flexibility.

Special inputs: As users do more video and photo editing at their PCs--and as more watch DVDs on them--more monitors offer inputs we used to see only on TVs or peripherals. Photographers and videographers may be interested in S-Video ports and memory card slots; DVD aficionados may want to keep their eyes peeled for monitors with component and/or composite inputs.

Response time: Pixel response time governs the time (measured in milliseconds) required for a pixel to change. In theory, a low response time signifies an LCD with minimal motion artifacts in moving images. This spec is especially important to video watchers and gamers.

There are two main types of LCD response time. Rise-and-fall response time measures the time it takes a pixel to turn from black to white (rise) and back to black (fall). Gray-to-gray response time measures the time it takes for a pixel to change from one shade of gray to another. Each type has its uses.

Rise-and-fall response time has been clearly defined and has been the industry standard for years. As of yet, no such definition for gray-to-gray response time exists. In theory, gray-to-gray response time could be a useful spec, since it can measure the time required to switch between shades (as opposed to black and white). This should make it useful for indicating how an LCD will look showing the subtle shades of movies and games. However, the lack of an agreed-upon definition means vendors may use different ways of determining the spec. In short, response time specs are not always comparable from vendor to vendor. For more information on this issue, see "LCD Specs: Not So Swift."

Size: Though it may seem obvious, bear in mind the size of your workspace when deciding on the type of monitor to buy. A huge monitor may look appealing, but you want to make sure your desk is deep enough to let you view it from a comfortable distance. Just as you would with a television, you want to sit at a distance of about two times the diagonal measurement from the screen.

Physical adjustments: Almost all monitors come with tilt adjustment. If you spend a great deal of time in front of your monitor, you may want to find one that lets you adjust the height of the screen as well. You may find that it's worth a few extra dollars to get a monitor that will keep the screen at a comfortable height instead of making your neck do all the work. A monitor with side-to-side swivel adjustment makes it easier to show your screen to a nearby customer or coworker. Finally, if you need to see view anything that's longer than it is tall--a full-page document, a long Web page, or a screen full of e-mail--you could get a lot of use out of a screen pivot function. Just bear in mind that not every monitor with a pivoting screen includes image pivoting software; you'll need that to make your screen adjust to portrait mode.

The Specs Explained

As with most PC peripherals, monitors introduce you to a ton of unfamiliar specs. While price or specifications alone shouldn't determine what you buy--what you'll use it for is important as well, and image quality is the most important thing to most users--here are some things to look for to narrow your search.
Flat-Panel LCD Displays: Features and Specifications Guide

Important: Native resolution. Images look best when displayed at an LCD's native resolution. You can go lower (and in some cases higher), but the image may appear blurry. The vector graphics of Windows Vista may lessen this, but native resolution will always look sharpest. Some models are better than others at handling non-native resolutions. (Remember that with LCDs the native resolution is the maximum resolution you can display.)

Important: Panel size. Unlike CRT (which indicates both tube-size and viewable-screen diagonals, LCD panel size indicates viewable size as well. As with CRTs, the measurement is made diagonally from one corner of the screen to the opposite corner. Too small a panel, and you'll have trouble cramming everything you need to see on your screen; too large, and may have to crane your neck.

Important: Physical adjustments. Height adjustment lets you adjust your monitor to a comfortable physical level. Swivel is useful for sharing your work, and pivot is handy for viewing applications that are taller than they are wide.

Somewhat important: Contrast ratio. Contrast ratio can help you determine how rich the color will be in on-screen images. A higher ratio is better, but vendor specifications are not always accurate.

Somewhat important: Viewing angle. Indicates how far you can move to the side of (or above and below) the center of the screen and still see what's displayed. This is important when you use the LCD to make presentations, or when you work with another person. Vendors use different methods to measure viewing angles, so make the final judgment yourself by visual comparison.

Somewhat important: Brightness. All LCDs generally provide more than enough brightness. In fact, most users find they have to turn the monitor's brightness down after purchasing.

Minor: Response time. Rise-and-fall response time Iindicates the time required for a pixel to change from black to white (rise) and back to black (fall). A low figure in milliseconds should indicate a screen that will not display only minimal motion artifacts in moving images during games or video. Gray-to-gray response time does not have a standard definition, and is a less reliable indicator.

Monitor Shopping Tips

Now that you know what specifications are available, read PC World's recommendations before you start shopping.
General Monitor Buying Tips

Try before you buy. When it comes to choosing the monitor you will be staring at for the next few years, only your eyes can tell you if a monitor's image quality, resolution, and size are right for you. Don't buy displays over the Web or by mail order unless the seller has an unconditional return policy and, ideally, no restocking fee. Checking out models in a store can be helpful, but keep in mind that they are often hooked up to low-quality video signals and placed under different lighting from what you have in your office or home. If possible, try to find a vendor with a liberal return policy, so you can try the monitor in your own setting before committing to the purchase.

Check screen real estate. Make sure you have enough screen for what you need to do. Remember that the viewable area of a wide-screen monitor is generally comparable to the viewable area of a regular-format monitor that's 2 inches smaller. Similarly, the viewable size of a CRT is an inch or two smaller than the advertised tube size--so if you're switching from a CRT to an LCD, you may not need as big a monitor as you think. Also bear in mind that if you're switching from an LCD with a regular aspect ratio to a wide-screen one, the wide-screen will have less real estate at the same diagonal measurement. A 19-inch wide-screen is comparable to a 17-inch regular-format LCD. The current sweet spots for display size are the 19-inch regular-format LCD and the 20-to-22-inch wide-screen LCD, both of which provide plenty of desktop space for most users.

Gain more screen space by using two monitors. Consider using multiple smaller monitors instead of one big one. With the right video card, you can run both simultaneously off the same PC. A pair of 17-inch LCDs will let you do video or image editing in one window, and word processing or Web browsing in the other. This can be a great way to get more use out of old monitors. If the double footprint gives you pause, consider mounting two small LCDs on a stand. Look for monitors with good screen quality and the VESA Flat Panel Mounting Interface and an FPMI-compatible stand.

Consider USB ports. Universal Serial Bus connections are designed for quick and easy attachment of numerous peripherals. When USB debuted, the physical accessibility of a monitor made it a natural choice for housing a number of the new, smart, hot-pluggable ports (although the inclusion of USB adds to a monitor's cost). The number of ports provided varies with different models, as does the number of ports that are up front versus on the back. Current monitors are likely to include USB 2.0 hubs. USB 1.1 is fast enough for hooking up lower-performance devices, such as keyboards, mice, and even broadband modems. USB 2.0 devices, such as CD-RW drives and hard drives, will work with USB 1.1 ports, but at lower speeds than with USB 2.0 ports.

Decide whether you want speakers. The inclusion of speakers in a monitor can be a nice way to save space on your desktop. But despite recent advances, their sound will rarely satisfy the discerning ear. If you're picky about sound quality, save the money for a nice set of speakers with a subwoofer.
Donate or Recycle Your Old Monitor

Never, ever send your old monitor to the dump. Recycling is not only good for the environment, but it's also a legal requirement in some states that will not accept monitors in regular municipal landfills. CRTs contain 4 to 6 pounds of lead plus other toxic materials that could leach into the soil and water in minute quantities if not properly disposed of. At this point, most LCDs contain lead and nearly all contain mercury.

As long as your old monitor is still working, it could be a boon to someone else. Check local listings for charities that accept computer equipment. If you'd like to help a lucky individual, join your local Freecycle group or post a notice in the Free section of the For Sale category of Craigslist.org in your region. If you're sure your old monitor is no good to anybody any more, check with the vendor or your local government to find recyclers in your area that can handle monitors.

Check out these stories for advice on recycling monitors and other electronic devices: "Tips & Tweaks: Recycle PCs, Notebooks, and Components" and "Easy Ways to Recycle Old PCs and Cell Phones--Really!."

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