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Choosing the Right
Monitor
How a monitor works and
what features are available on monitors are summarized in the following
table.
Screen Size
The screen size of a
monitor is the one feature that most affects price. Common sizes of
monitor screens are 14- inch, 15-inch, 17-inch, and 21-inch. The 15-inch
monitor is the most popular, and the small 14- inch monitor is losing
popularity.
When matching a monitor
to a video card, a good rule of thumb is to match a low end video card to
a small, 14- inch monitor, a midrange video card to a 15-inch monitor, and
a high-end video card to a 17-inch or larger monitor to get the best
performance from both devices.
You can compare the
different features of the video card to those of the monitor, such as the
resolutions supported, the refresh rate, and the bandwidth.
Bandwidth
is the difference
between the highest and lowest frequencies that an analog communications
device such as a video cable can carry. Macintosh computers can use
special monitors designed for page layouts on legal sized paper. The
larger the screen size, the more expensive the monitor. Even monitors
advertised as having a 17- inch screen might only have a lighted screen
area of 912 inches by 1112 inches. The diagonal measurement of the lighted
area is 15 inches, and the diagonal measurement of the screen surface is
17 inches.
Refresh Rate
The refresh rate, or
vertical scan rate, is the number of times in one second an electronic
beam can fill the screen with lines from top to bottom. Refresh rates
differ among monitors.
The Video Electronics
Standards Association (VESA) has set a minimum refresh rate standard of 70
Hz, or 70 complete vertical refreshes per second, as one requirement of
Super VGA monitors. Slow refresh rates make the image appear to flicker
while faster refresh rates make the image appear solid and stable. Mullica
monitors offer a variety of vertical and horizontal refresh rates so they
can support a variety of video cards. They cost more but are much more
versatile than other monitors.
Interlaced or
Non-interlaced
Interlaced
monitors draw a screen
by making two passes. On the first pass, the electronic beam strikes only
the even lines, and on the second pass the beam strikes only the odd
lines. The result is that a monitor can have a slow refresh rate with a
less noticeable overall effect than there would be if the beam hit all
lines for each pass.
Interlaced monitors
generally have slightly more flicker than non-interlaced monitors,
which always draw the entire screen on each pass. Buy a non-interlaced
monitor if you plan to spend long hours staring at the monitor. Your eyes
will benefit.
Dot Pitch
The
dot pitch is the distance between the
spots, or dots on the screen that the electronic beam hits. Three beams
build the screen, one for each of three colors (red, green, and blue).
Each composite location on the screen is really made up of three dots and
is called a triad.
The distance between a
color dot in one triad and the same color dot in the next triad is the dot
pitch. The smaller the pitch, the sharper the image. A dot pitch of .28 mm
or .25 mm gives the best results and costs more, although less expensive
monitors can have a dot pitch of .35 mm or .38 mm. These less expensive
monitors with dot pitches of .35 mm or .38 mm can still create a fuzzy
image even with the best video cards.
Resolution
is a measure of how
many spots on the screen are addressable by software. Each addressable
location is called a pixel (for
picture element) that is composed of several triads. Because resolution
depends on software, the resolution must be supported by the video
controller card, and the software you are using must make use of the
resolution capabilities of the monitor. The standard for most software
packages is 800 by 600 pixels, although many monitors offer a resolution
of 1024 by 768 pixels or higher.
The resolution is set
in Windows from the Control Panel and requires a driver specific for that
resolution. Higher resolution usually requires more video RAM.
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