Buying an LCD? Start here

[FZ1]

Before plunking down your hard earned cash on an LCD monitor, here are a few things to look for when shopping so you understand what you are looking for.

Input Type: Make sure the monitor has a DVI connector even if you do not own a video card with DVI output. When you do upgrade, you monitor will be ready. Most come with adapters if your graphics card does not support it anyway. The DVI signal is all digital versus the 15-pin D-Sub connector which is analog. Analog signals are inherently less accurate than digital although one cannot always discern a difference between the two.

Resolution: A monitor screen is made up of individual dots of color, or pixels. Resolution refers to the number of pixels contained on a display and is typically expressed by identifying the number of pixels on the horizontal axis (rows) and the number of lines on the vertical axis (columns), such as 1024x768. A higher resolution generally results in smoother graphics and can fit more information on a screen at once. Because an LCD uses a matrix of cells to display its image, it has a fixed resolution, called its native resolution, also called optimal resolution, at which the display looks best.

Response Time: Response time (measured in milliseconds) refers to the time that it takes the LCD pixel to go from black (with an index of 0) to white (index of 255) and then back again. Do not confuse this with frame rate. Note that this is only at the pixel level and not the whole screen. The response time for the transition of one color to another may vary depending on how far those colors differ in the color spectrum. Therefore, there is a variance in the response times from color to color and manufacturers typically report the best (lowest) measured response time rather than an average or highest time.

You can also measure response time in "gray-to-gray" (GTG) response time. The measurement of GTG response time is actually more a useful metric as it is the more typical pixel transition when gaming or watching video. Rarely are images going from pure black to pure white (or vice-versa). As the name implies, GTG response is the time that it takes for a pixel to go from one shade of gray (the other 244 colors) to another. Again, the response time varies from shade to shade and again the manufacturers typically report the best measured GTG time rather than an average. In fact, many do not report this metric at all. It is worthy to note that a 10ms response time LCD may only yield a 20ms GTG response time so there is a substantial difference between them and different LCD’s will have differing response rate ratios between the two. The lower the time, the less smearing/ghosting the user will see. People tend to have different thresholds regarding response times and smearing/ghosting. One person may notice it at 15ms while another may not even notice it at 20ms.

Color Depth: Color depth indicates how many colors can be displayed on a monitor's screen. It is usually talked about in bits (short for "binary digits"), describing how many bits are used for each of the three additive primary colors-red, green and blue-per pixel. So, for example, if 8 bits are dedicated to each of the three colors, the color depth is 24-bit (8 bits x 3 colors = 24). The bit depth determines the number of colors that can be displayed at one time. Almost all LCDs today are 6-bit or 8-bit. A typical 8-bit LCD can produce 256 shades per pixel, or 16.7M color combinations (256 red x 256 green x 256 blue). A 6-bit LCD panel can display 64 shades per pixel, so overall the monitor can display 262,000 color combinations per pixel. Stick with the 8-bit screens if possible, why would you not want to see the full spectrum of colors? This is a must if you are doing graphics/design.

Brightness/Contrast Ratio: Brightness is the luminosity of white color (i.e. the matrix receives the maximum signal) in the center of the screen, and contrast (or contrast ratio) is the luminosity ratio of white to black, also in the center of the screen.

Contrast ratio 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 to 600:1. Lower and colors may wash out or disappear when adjusting brightness and higher ratios typically do not appear to be visually superior in quality. Note that contrast originally measured the difference between the lightest light and the darkest dark on the LCD. However, like response time this measurement can be and is measured in a variety of ways and are usually measured and reported to the manufacturer’s advantage.

Most LCD monitors are passive and modulate rather than radiate light so the brightness is provided by a backlight unit behind the LCD matrix. The opaqueness of the LCD matrix defines the brightness which is expressed in candelas per square meter (cd/m2) or nits. It represents the measurement of the greatest amount of light that comes from the screen when displaying pure white. Most LCD’s have a brightness level of 250cd/m2 or greater compared to CRT monitors that typically average ~100 cd/m2. Higher is better in this case. Note that retailers typically set the brightness level to maximum on floor models to impress customers – oooooooh, ahhhhhhh. Using the brightness at high levels over time will reduce the lifespan of the LCD lamps. This is typically measured in terms of “half life�. A monitor with a stated half life of 2000 hours will last much longer but the brightness will deteriorate.

Viewing Angle: Viewing angle is typically not an issue for the more recent LCD’s as technology has improved. An LCD's viewing angle indicates how far, in degrees, you can move from the center of the display before the image quality deteriorates to unacceptable levels. This is something to look for when viewing the monitor in person.

Here are some pros & cons:

CRT:
Pros:
-Relatively Inexpensive (although the gap is closing)
-Multisync Capable
-High Refresh Rates
-Color Clarity and Depth
-Mature product, very few improvements on the horizon (no need to upgrade before end of product life)
-No view angle limitations
Cons:
-Screen flicker
-Space hog
-Heavy, not easily moved
-No rotation adjusments & no height variability built in
-High energy consumption
-Produces excess heat
-Generates electromagnetic interference (gives some people headaches)
-Shorter lifespan (average of 10k-20k hour half lives)

LCD
Pros:
-No flicker
-Takes up Little Space
-Light Weight
-Energy Efficient (~1/3 less power needed)
-Prevents Eye Fatigue
-Longevity (half life is about 50k hrs on avg)
-Many LCD's now come with extras (height adjustable, physical screen rotation, USB ports, speakers, etc).
-Ease of portability (i.e. - Lanparties)
Cons:
-More expensive
-Blurry Images Outside Native Resolution
-Motion Blur on Fast Moving Images (depending on response rate. This is improving)
-Washed Out Colors
-Newer technology so improvements are still being made
-Dead pixel possibility
-Limited viewing angles (varies)


Feel free to tack on any I missed.

[Capper]

man, outstanding write up, thank you for sharing

[GV2NIX]

Under "CONS" for LCDs you might want to also put

Narrower viewing angle

and

Possibility of dead pixels

[Anonymous]

It would also be worth haveing a little section saying what applications are better suited for CRT and LCD.

For example CRT's are not good for lanparties, trust me i know, standing in line at quakecon with a 24" CRT was less then fun.

[FZ1]

LOL, I would hope that would be common sense!

[Anonymous]

common sense??? there is no such thing.

[gvblake22]

Originally Posted by infinitevalence

common sense??? there is no such thing.

Quoted for Truth!!!

[GV2NIX]

Since we're on the topic of low-profile displays, do you think it would be useful to explain the difference between LCD and plasma? The distinction between those two technologies confused me for a while years back, so I figured it would be informative for those who are still mystified. If that would be out of place, please say so, but I thought I'd just offer the idea. If no one wants to bother, I wouldn't mind starting a list of comparisons. :)

Edit: Something like this would probably be better-suited for the "General Technology" section huh?

[FZ1]

To your last question, probably. Nobody (that I know of) uses plasma for computer screens as they are cost prohibitive. Plasma shares a lot with LCD as far as pros and cons however.

I posted this because I had collected a lot of data when I was looking at LCD's and decided that the information would be useful to others. I made a few updates and voila! I tend to do A LOT of research on products before I drop money on them.

[GV2NIX]

Originally Posted by FZ1

I posted this because I had collected a lot of data when I was looking at LCD's and decided that the information would be useful to others. I made a few updates and voila! I tend to do A LOT of research on products before I drop money on them.

Such are the ways of wise people, haha! Not doing tons of research before hand only increases the risk of mistakes, e.g.not realizing that the ATX power connector standard is changing, and things of that sort... :roll: