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BASICS ABOUT LCD
MONITORS
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| Although
you'll still pay two or three times as
much as for an LCD as you would for a
CRT of similar size, the cost of flat
panels continues to fall. When shopping
for an LCD, some specifications and features
are more important than others. Here are
a few of the biggies. |
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Aspect
ratio: The standard proportion in width
to height for a computer monitor is 4:3, but
some new displays have a wider format: 16:9
or 16:10, designed for viewing movies or HDTV
in wide format. Note that a 17-inch wide-format
panel has about the same vertical dimension
and vertical pixel count as a normal 15-inch
panel, so you get about 120 percent of the viewing
area of a 15-inch panel. A 17-inch standard
panel, however, has 130 percent of the viewing
area of a standard 15-inch screen.
Contrast ratio: A spec much hyped by
manufacturers (be suspicious of their claims),
this is the difference in light intensity between
the brightest white and the deepest black.
Digital and analog connections: LCDs
are digital devices and thus have to convert
analog (VGA) signals before they can be displayed.
A graphics card with a digital video interface
(DVI) can send the signal straight to the display
in digital format--no conversion required. Most
LCDs come with an analog input (featuring a
D-shaped connector that has 15 pins arranged
in three rows, sometimes labelled D-Sub), some
come with both, and only a very few come with
just a digital input. Nevertheless, at this
point, most monitors do such a good job of signal
conversion that digital connections are not
as important as they used to be.
Digital
input |
Analog
input |
Luminance: Brightness; a measure of how
much light a panel can produce. Luminance is
expressed either in nits or candelas per square
meter (cd/m²). A measurement of 200 to
250 nits is OK for most productivity tasks;
500 nits is better for TV and movies.
Pixel-response
rate: This refers to how quickly a pixel
can change colors, measured in milliseconds
(ms); the fewer the milliseconds, the faster
the pixels can change, reducing the ghosting
or streaking effect you might see in a moving
or changing image. In general, manufacturers'
specifications rely on best-case scenarios;
real-world performance could be slower. A maximum
of a 12ms-to-15ms response time across the spectrum
is required for gaming or viewing television
and movies without ghosting or streaking. We've
only just begun to see LCDs with superfast pixel-response
times, such as Samsung's SyncMaster 172X and
BenQ's FP767-12.
Portrait/Landscape modes: Some LCDs pivot
so that the longer edge can go horizontal (Landscape
mode) or vertical (Portrait mode). This feature
can be useful for desktop publishing, Web surfing,
and viewing large spreadsheets, but don't pay
extra for it if you won't use it.
Portrait
mode |
Landscape
mode |
Resolution: Make sure you are comfortable
with an LCD's native resolution before you buy
it. Remember, an LCD that scales its image to
a nonnative resolution will never look as good.
Viewing angle: The physical
structure of LCD pixels can cause the brightness
and even the color of images to shift if you
view them from an angle rather than facing the
screen directly. Take manufacturer's specifications
with a grain of salt and make your own observations
if possible; viewing-angle issues become more
critical as panel size increases.
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