Navigating LCD monitor specs and is an LCD really what you want anyway?
Jan 02 '07
The Bottom Line The decision to move to LCD from CRT is not a no-brainer. There are some pros and cons depending on your intended use.
The 19 inch CRT monitor which had come with my 3.1 year old desktop system had been making popping sounds for a while, which I knew from experience was a warning sign that its days were numbered. Therefore I was not surprised when I got a call at work one day from my wife telling me my monitor had finally succumbed. I immediately began researching what was available locally in LCDs as far as price and features. I had a spare monitor available at the office (17 inch CRT) which was slated for the trash, so I rescued that from certain death and brought it home as a temporary solution. It was so small in comparison to the 19 inch that my wife resorted to her laptop and I settled in to the mini screen with the comforting knowledge that it would only be temporary. You see I had come across a variety of options in available LCDs on the internet and just needed to take the time to zip over to the store and see these things in operation before deciding which brand and model to purchase. I got a chance the next day to visit the local electronics megastore and was able to see about 30 monitors all set up all displaying the same image which made it easy to compare the quality. Here is some of what I was looking at with explanations and some notes on what I have learned about LCD monitors in the process.
Choosing LCD vs CRT
LCDs are all the rage these days, something which was driven home by the fact that nobody even bothered to take my old 19” CRT from the trash when it sat on the curb for over 24 hours. Is this preference for LCD over CRT legitimate or just hype?
The first consideration when purchasing any monitor these days is the size of the display area. The effective display size of a 19 inch LCD monitor will be roughly equivalent to a 21 inch display size in a traditional CRT monitor. The cost of LCD has come down considerably and pricing for mid-size (19-21 inch monitors) in both LCD and CRT are roughly equal with respect to the above sizing between the two.
Some Benefits of CRT Over LCD
Supports Different Resolutions
So with price out of the way, why would one still want to consider the old CRT technology over the newer LCD? The technology upon which CRTs are built on is much like that of your TV where light is projected onto the screen from inside in the back of the unit to create an image on the outside of the front of the screen. With LCD the screen is made up of liquid crystals which can be made to change shades by applying electric current. Inherent in the design of CRT is the ability to resize images and change resolutions with great accuracy as the image is simply re-projected onto a bigger or smaller area, while with LCD images are not projected and can thus only be stretched LCDs are capable of only one true resolution and when stretched to accommodate a different size will result in some loss of clarity.
Quicker Refresh
This is a big issue with gamers. When a CRT monitor changes what it is displaying you are dealing with the speed of electric current traveling around a very small area to change what is being projected, and then the time is takes light to project the depth of your monitor which is pretty fast. With LCD the liquid crystals need to change shade and this takes time which can result in some shadowing and lag which can be especially apparent with gaming. The latest LCDs have some very fast refresh rates making this less of a concern that it used to be, but the idea behind it is still there and for the hard-core gaming crowd CRTs may still be preferred.
So, What are the Benefits of LCD?
LCD monitors are flat and this take up less space and weigh considerably less. You get more effective display with a slightly smaller screen. The power consumption is less and they just look cool. In my experience the color control and contrast can be set higher and still be comfortable and I am told that in good light, they are easier on the eyes than CRTs.
Specifications
So once I decided on an LCD to replace my old CRT, I looked at the specs on paper to narrow down my choices.
Input Type
The first thing to look for is a monitor which can produce a digital signal. Most these days have analog and digital and advertise that. Digital output will be sent using a DVI connector whereas analog uses the same typical 15 pin D-Sub connector that you would have used for a CRT since VGA came on the market. You will need a video card that can handle DVI. If your computer is relatively new this should be the case. If not consider buying a DVI capable LCD monitor anyway because your next computer will support it.
Resolution / Aspect Ratio
As described above, LCDs are capable of one resolution only. It is important to be aware that for a LCD monitor with an aspect ration of 4:3, you should have a resolution of 4:3 as well. This means 1600x1200, 1280x960, or some derivative thereof. Most LCDs have an aspect ratio of 5:4 (1280x1024) which is usually not an issue. However the signal is being crammed down from 5:4 to 4:3 and if you do any kind of graphic work you may notice that circles will be ovals and measurements will not necessarily be accurate – circles will appear as ovals. Beware if buying a widescreen LCD with a widescreen resolution. A 30” wide format LCD with a 1024x768 (4:3) resolution will not look right no matter what you do to the signal.
Response Time
This is the time it takes an LCD pixel to turn from fully ‘on‘ to fully ‘off’. This has nothing to do with the frame rate as pixels respond independently of each other. Response times these days run from about 15ms to a low of 2ms with most somewhere around 6 to 8ms (lower of course being better). Most people are hard pressed to see the difference that response times in milliseconds actually make, but again this is a comparative measure and gamers might be more inclined to go for faster response times in order to insure sharper transitions without lag.
Brightness
Brightness is determined by the amount of light, measured in "candela per meter squared" or "cd/m2" or "nits", that actually filters through the front of the monitor at a 90 degree angle. Higher is better.
Contrast Ratio
This is a measure that is a little hard to trust (they all are actually) as manufacturers have abused the original intent of the measure by taking the measures on angles to make them seem better. Some sites no longer even include this spec. What it basically means is the difference between the lightest light and the darkest dark on the LCD. Thus for a monitor with a white brightness of 300 cd/m2 and a dark brightness of 0.15 cd/m2 would be a contrast ratio of 2000:1 which is a pretty good ratio, on paper at least.
Color Depth
LCD monitors today are either 6-bit or 8-bit. This affects how many shades per subpixel (red, green, blue) can be displayed and correlates directly the number of possible color combinations. An 8-bit LCD panel can display 256 shades per subpixel, or 16.7 million color combinations. A 6-bit LCD panel can display 64 shades per subpixel which is 262,000 color combinations. Quite a difference. Manufacturers will often list this spec in relation to pixels rather than subpixels, so since there are three subpixels to each pixel, if you see a number other than 6 or 8 divide it by three.
A Further Word About LCD Monitor Specs
I’ve listed some of the main specifications used to compare most LCDs. There are others, but as I mentioned already some of these specs are susceptible to manipulation by manufacturers and although they may be useful as an initial way to narrow down the search, they really should be taken with a grain of salt and I would be weary of buying a monitor unseen on specs alone.
There are reasons which prevail for staying with CRT and LCD depending on your needs and LCDs have not been able to completely replace CRTs especially in commercial applications which are graphic intensive and where measurements, photo editing, etc are of high importance. For my individual needs the benefits of LCD were a good fit and my decision was to purchase a Samsung 931BF based partly on specs (best response time on the market) and finally on comparing the picture side by side with competitive models.
I have only owned my monitor about 2 months at this writing, but am so far very pleased. I have noticed the limitations on enlarging images and on having to use the LCDs maximum resolution vs the very high resolutions which I use to use on my CRT (things on the screen were very small, but I could fit a lot on there). One solution to this is to acquire two video adapters and two monitors and place them side by side. Windows XP has the built-in capability to span your desktop display across two monitors at once f they are present – but this is an expensive option and I have at present decided to wait and see how much these restrictions will affect me before committing to the additional outlay
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