A Guide to Choosing a LCD zt

How to Pick a Good LCD Picking an LCD goes well beyond brand recognition. Below, we have a small introduction to a few different facets of shopping for an LCD - in our order of importance. Generally, we find a price point and then choose an LCD based on the properties detailed below. For example, if we only have $500 to spend, we consider all of the monitors for $500 or less and go through the following checklist. Input Type: DVI, DVI, DVI. We insist that when you buy a new LCD monitor, you buy a model with DVI capability. Even if you don't want to buy a DVI-capable video card right now, it is still a wise decision to get a DVI-compatible LCD. When DVI first appeared in the industry, there were a few issues with the quality of the connectors and thus, sometimes viewing a signal over a DVI connector would give you a worse signal than over a 15-pin D-Sub connector. However, in the last 3 or 4 years, most of those problems have been fixed, and virtually every new video card is more than capable of producing a clean digital signal. None of the LCDs that we review today (except the Samsung 910V) are limited to only analog connectors, but be aware that they exist. Resolution, Aspect Ratio: If you buy a 4:3 LCD, the resolution had better be 4:3 as well. That is, a 19" LCD should have an aspect ratio of 1600x1200, 1280x960, or some derivative thereof. Most 19" and 17" LCDs have an aspect ratio of 5:4 (1280x1024). This is OK, but you're looking at a 5:4 signal crammed in a 4:3 box. Our Dell 2001FP, on the other hand, measures exactly 16" by 12" and runs at a resolution of 1600x1200. Generally, a skew aspect ratio is not enough to notice, but if you do any sort of graphic work, all of your circles will look like ovals. This goes the same for widescreen LCDs - buy a widescreen LCD with a widescreen resolution; a 30" wide format LCD with a resolution of 1024x768 will not look correct no matter what you do to the signal. Response Time: Response time is an unusual preference and always a trade off. Typical response time (TrTf - Time rising, Time falling) refers to the time that it takes the LCD subpixel to twist from the fully "on" position to the fully "off" position and then back again. Response time has absolutely nothing to do with framerate. Pixel response times are independent of each other, and it does not take the entire screen 25ms to refresh if a monitor is labeled as a 25ms response time LCD. The time that it takes the LCD to go from black to white may be 15ms while the time that it takes the LCD to go from black back to white may be 10ms. Furthermore, your monitor is generally rendering a color that is not on end of the color spectrum. The time that it takes your LCD subpixel to twist from one half of a tone to another may be more or less than 15ms. The TrTf response time is normally a pretty useless measurement - but it makes for an easy specification in which to market LCDs. The second method in measuring response time is "gray-to-gray" (GTG) response time. The measurement of GTG response time is actually more useful to LCD buyers, but it is harder to convey and is usually just conveyed as one number (which is incorrect). Gray to Gray response time refers to the time that it takes for a pixel to twist from some arbitrary position to another. On a 6-bit LCD, that's the time it takes the subpixel to twist from 1 of 64 different positions to one of the other 63 positions. GTG response times are useful if the manufacturer expresses the average of all the GTG response times, but that is rarely the case. Everyone's preferences on response time are different. If you play a lot of games and feel that the few ms difference between a 6-bit LCD and an 8-bit LCD are worthwhile, then it's a worthy investment. Most people can't tell the difference - and that's not just most people who aren't gamers, but most people in general have to be shown the differences between two displays that differ by single digit transient response times. How to Pick a Good LCD (continued) Color Depth: Almost all LCDs today are 6-bit or 8-bit LCDs. This means that each subpixel - Red, Green, and Blue - can display one of 2 to the n shades where n represents the number of pixels. A typical 8-bit LCD can produce 256 shades per pixel, or 16.7M color combinations. A 6-bit LCD panel can display 64 shades per subpixel, and since there are three subpixels per pixel, the monitor can display 262,000 color combinations per pixel. This is generally OK for gaming, but certainly not acceptable for any graphics development. Personally, I enjoy seeing the other 98% of the 24-bit color spectrum. Brightness: Brightness is fortunately an easy specification to remember. More is better, particularly on LCDs with higher resolution. Even though your LCD might have six bulbs behind the substrate, a very small fraction of that light actually filters through the liquid crystal. Although, the measurement of "candela per meter squared" or "cd/m2" or "nits" all refer to the amount of light that actually passes through the front of the monitor at a 90 degree angle. Viewing Angle: Viewing angle generally has a lot to do with the display mode of an LCD. You may wish to check out our LCD FAQ from a year ago that went through a lot of the basics of LCD design, particularly the pages on how LCD substrates work. Differing display modes utilize differing methods for twisting the LCD crystals - TN, PVA and SIPS are just a few. When LCDs were new, there were large issues with getting light to pass through the substrate at more angles than just 90 degrees head on, and for a short period of time, it was important that LCDs have some viewing angle. However, almost all LCDs today (and for the last 3 years or so) have viewing angles that are wide enough for anyone to look at the LCD from any (sane) angle. Unless you spend a lot of time looking at your monitor from 3 feet away, 60 degrees off center and at a 45 degree incline, don't worry about viewing angle so much when buying an LCD. We generally only mention viewing angle in our reviews if something seems amiss. Contrast Ratios: Contrast measurements were originally supposed to quantify the difference between the lightest light and the darkest dark on the LCD. For example, if a black portion of the screen has a brightness of 0.5 cd/m2, and a white portion has a brightness of 250 cd/m2, then the monitor would have a contrast level of 500:1. Almost immediately, this measurement has been abused; manufacturers can take these measurements on angles to assure darker darks and brighter brights. Furthermore, other manufacturers take these measurements in different light settings and with different test pattern (some take measurements with the screen completely dark, while others take measurements with the screen in a checkerboard pattern). Unfortunately, relying on manufacturer Contrast Ratios too heavily during a purchase will probably lead you astray. To correct that, we will run a standardized test in our lab that tests contrast ratios of all of our LCDs in controlled situations. So far, we covered only the introductory basics in shopping for an LCD. Footprint, features and rotation capabilities are all important as well, but don't be awed by monitors with features that you will never use. Paying $50 extra for MagicBright or a TV tuner only makes sense if you're going to use it.