Dot Pitch - This can be one of the most
misleading facts available to you when comparing monitors. Dot pitch is measured
diagonally between two adjacent phosphor dots of the same color expressed in millimeters.
If you remember from the intro, I explained that there were three colored phosphor dots
(Red, Green and Blue). These dots are arranged on the screen in what are called triads.
What most people fail to understand is that you can only compare dot pitch between
monitors of the same type. Below are three different types of masking used in CRT
monitors. I'll explain what a mask is shortly.
- Dot Mask - The screen mask has little holes in the shape of dots.
- Slot Mask - The screen mask has vertically elongated holes.
- Aperture Grill - No screen mask, but uses thin vertical strips.
So what is this mask thing I'm talking about? The mask is a very fine mesh screen that
is applied to the back side of the screen which allows electrons to hit only the phosphor
groups. Think of it this way, anyone who has ever used stencils before knows that the
paint will only be applied to the object being painted through the holes/shapes/letters in
the stencil. It works the same way for the mesh screen. For each of the three different
types of masks, they offer some advantages and disadvantages over the others.
Slot mask offers a little advantage over dot mask in that it allows more of the
electron beam to pass through, therefore providing an overall brighter picture. Aperture
grill allows even more electron beam to pass through, but has one distinct disadvantage.
Because the thin vertical strips are less stable in structure than a mesh screen, they
must run two or three horizontal stabilizing wires (called damper wires). While they are
very thin, you can still see a shadow of the wires on the screen (the shadow is created
because the wires are between the electron guns and the phosphors on the screen.) One
thing I've discovered, is that it is a very similar phenomenon to the letterbox standard
on videocassette. That's where there is a black horizontal bar on top and bottom of the
actual movie picture. At first it was distracting, but after watching a few movies in that
style, it basically becomes unnoticeable. It's the same way with the horizontal shadows on
the aperture grill monitors. They're extremely bothersome at first, but after time it gets
to the point where you don't even notice them anymore.
With that out of the way, and you are trying to decide between two monitors and they
are pretty much equal in all other areas, get the one with the smaller dot pitch. a .26 is
better than .28 and .25 is even better still.
Another factor you should consider is monitor size.
