The three most common things about monitors that are looked at when you are considering which to buy are dot pitch, resolution, and the refresh rate.
The dot pitch is a measurement of how close together the pixels, or phosphor dots, are that make up an image. For the most part, the finer the dot pitch, the better image quality you will have. But, the subject of dot pitch is actually a little confusing. No longer can one just assume that the smaller dot pitch is better.
The dot pitch is dependent on the type of monitor. The traditional dot pitch on a shadow-mask monitor is measured diagonally from one phosphor dot to the next of the same color. The horizontal dot pitch is, then, the distance from an imaginary line drawn through all same-color phosphor dots in a vertical column to the next over such line. Both of these monitors use the same construction, but the dot pitch is measured differently, and can’t be compared. On aperture-grill monitors, such as the Sony Trinitron, a stripe pitch is used, and is the distance between two same-color stripes in the display. Here, a 0.25 dp is standard, while 0.28 dp is standard on a shadow-mask monitor. They can’t be compared, then, by dot pitch alone.
The motto here is not to pay too much attention to dot pitch when considering your next monitor.
Resolution and Refresh Rate
These two features are discussed together because neither can really be discussed alone. Each depends on the other. They work hand-in-hand to produce a clean image, and they both depend on the bandwidth available from your video card.
Refresh rate is the vertical frequency, or the rate at which each pixel on a screen is re-drawn. A low refresh rate result in an image that flickers, resulting in eye-strain. Due to limits in bandwidth, the rate at which the screen is redrawn decreases as the resolution increases. Bandwidth is the rate at which the monitor receives data from the video card. To find out how much bandwidth is needed at a particular setting, simply multiply the horizontal resolution by the vertical resolution by the refresh rate. For example, a refresh rate of 85Hz at 800×600 resolution would require 40.8 MHz bandwidth. According to this, you can see that as the resolution increases, the required bandwidth increases dramatically.
The standard for flicker free images has been set to 85Hz. Nevertheless, most viewers won’t detect flicker as low as 72 Hz. The best test to detect flicker is to look slightly above or to the side of the monitor. Your peripheral vision is more sensitive to the flicker, therefore you have a better chance of seeing it. Sometimes, it helps to be in a darker room.
Your video card plays an important role in all of this. If your card cannot provide support for the resolutions and refresh rates of the monitor, the picture will look degraded. When pairing a video card with a monitor, at least make sure that it is capable of delivering a 72Hz refresh rate at any resolution supported by that monitor.
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