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20 All monitors are not created equal. (Macintosh hardware)


This article is from the Macintosh hardware FAQ, by Elliotte Rusty Harold elharo@shock.njit.edu with numerous contributions by others.

20 All monitors are not created equal. (Macintosh hardware)

Choosing a Mac monitor used to be simple. Like the Model-T Ford you
could have any color you wanted as long as it was black (and white),
9", 512 by 342 pixels, 72 dpi. The PC drones made fun of the small
size and lack of color, but it was obvious to any unprejudiced person
who looked at a Macintosh that its display was far superior to the
CGA and EGA monitors being foisted on ignorant PC consumers. Mac
monitors are no longer so simple. Now one needs to be concerned with
such arcana as resolution, size, bit depth, dot pitch, and refresh

Size is the most obvious characteristic of a monitor. It's measured
diagonally from one corner of the screen to the opposite corner.
Actual monitor area is roughly proportional to the square of the
diagonal length so a twenty-inch monitor is more than four times as
large as a nine-inch monitor. Most manufacturers cheat on their
monitor sizes by measuring from one corner of the screen (or even the
case) to the other rather than from one edge of the visible display
to the other. Then they round up to the nearest inch with the result
that most "fourteen-inch monitors" are closer to twelve and a half
inches when measured truthfully. For many years Apple was one of the
most honest manufacturers, advertising it's twelve and a half inch
monitor as a thirteen inch monitor while other manufacturers touted
their "larger fourteen-inch" twelve and a half inch monitors.
However Apple has succumbed to the pressures of the market, and like
everyone else it now advertises twelve and a half inch monitors as
"fourteen inch displays."

Of course it's not the size that matters; it's how you use it.
Resolution defines how much information can be squeezed onto the
screen. Most monitors sold today are "multi-sync"; that is they are
capable of displaying more than one resolution. A fifteen inch
monitor at 1024 by 768 pixels displays two and a half times as much
information as the same monitor at 640 by 480 pixels. However
everything will appear smaller at the larger resolution since the
monitor has to fit more pixels into the same space. The clearest
resolution for a monitor is whatever comes closest to fitting 72
pixels (or dots) into each inch. This is the dpi rating of the
monitor. 72 dpi is the proper "WYSIWIG" (Pronounced Whizzy-wig, What
you see is what you get) resolution though some people prefer to
work at a higher resolution that fits more information on the screen.
Here are the WYSIWIG resolutions for common monitor sizes. If you do
the math you'll notice that the resolutions seem too small for the
given size. That's because I've listed sizes here in their commonly
advertised form rather than by the actual paintable area on the

                  Size         WYSIWIG Resolution
                    9             512 by 342
                   12             512 by 384
             13,14,15             640 by 480
                16,17             832 by 624
                   20            1024 by 768
                   21            1152 by 870
                   25            1280 by 1024

Resolution and bit depth define how much you can see on your screen.
Dot pitch defines how well you can see it. It's the distance between
the holes in the grille through which the electrons are pushed before
impacting on the screen phosphors. Larger dot pitches look fuzzier.
Trinitron monitors paint the picture in lines rather than dots so
this doesn't really apply to them. However the "line stripe" of a
Trinitron display means almost the same thing in practice as dot
pitch does for other monitors, and most salespeople and copywriters
are happy to confuse the two for you. A .25 mm stripe pitch is
very close to a .28 mm dot pitch. Most monitors have dot pitches
of .39 mm, .28 mm, or .25 mm. The larger the dot pitch the fuzzier
your screen looks. .39 mm dot pitch monitors (the standard in the PC
world) look bad. .28 mm dot pitch monitors are acceptable for all
but the most demanding users. .25 mm is the best dot pitch available
with current technology, and really only necessary when you're driving
a small (15") monitor at a very high (1024 by 768) resolution.

Refresh rate also affects how clear the picture appears. 72 Hz is the
standard refresh rate for Mac monitors. That means the screen is
repainted 72 times a second, more than twice as fast as your TV
screen. A few monitors even repaint at an 80 Hz refresh rate though
I suspect that's overkill for all but the most sensitive eyes.
However many cheaper PC monitors have refresh rates of 60 Hz or even
less. This begins to reach the level that contributes to eyestrain.
Worse yet these monitors are interlaced, which means that only half
of the screen is redrawn on each pass. Interlaced monitors have a
visible flicker effect, and should be avoided at all costs. Leave
them on the shelves for the deluded PC users who think saving $50 on
a monitor is worth spending $500 at the optometrist.

Most Mac monitors are at least 69 dpi, 0.29 mm dot pitch with refresh
rates of 72 Hz. This is acceptable for most work. The only common
exception is the Apple Basic Color Monitor. This was Apple's VGA
monitor for low cost systems and was laughed out of the marketplace.
(At the time it was the standard in the PC world which gives you some
idea of the lower standards on the other side of the fence.)


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