For a few years in the ’90s, dot pitch was a really big deal. It was one of the standard ways people compared computer monitors. Lower dot pitch was better, and worth paying a premium to get. But what is dot pitch in computer graphics? What is dot pitch in a computer monitor?
What is dot pitch in computer graphics? What is dot pitch on a computer monitor?
Dot pitch on a computer monitor or in computer graphics is, to put it simply, a measurement of the size of the pixel that makes up the display. The smaller the dot pitch, the more pixels the display can cram into a millimeter, and the clearer the display will be.
We are talking fractions of a millimeter here, but it makes a difference. When I sold computers at retail, we would set up computers side by side, with the cheapest model in the line on the left and the most expensive model on the right. We paired the cheapest model with the cheapest monitor, which inevitably had a .39mm dot pitch. The middle machine had a monitor with a .28mm dot pitch. Even when running at the same resolution, the monitor with the lower dot pitch had a clearer display with less pronounced scan lines.
The low price of the machine on the left got shoppers attention. But unless someone was on a really tight budget, they wanted One of the machines in the middle. It was noticeably nicer, without seeming overly extravagant.
The dot pitch controversy
LCD monitors took the focus away from dot pitch. LCD panels have a native resolution, and if you display anything other than the native resolution, they scale it. So the focus shifted away from dot pitch to simply resolution. You bought the panel that displayed a resolution you wanted at the size you wanted, and that was it.
And that has led to the perception that LCDs have pixels but CRTs do not. That isn’t the case. It’s just that LCDs and CRTs scale differently, and CRTs scale lower resolutions more smoothly than LCDs do.
Think of it this way. When an LCD is displaying at its native resolution, the picture quality is a 9 or 10 out of 10. When it is displaying something other than its native resolution, the quality is probably a six or seven out of 10. It looks unnatural. The CRT display is going to be an eight out of 10, but it’s 8 out of 10 regardless of the resolution. The CRT is more consistent, although the LCD is better when it’s at the top of its game.
What is a good dot pitch on a computer monitor?
The gold standard for dot pitch was .28mm. Some premium tubes could exceed that slightly, but generally speaking, .28mm gave a clear display at SVGA resolutions. .39mm was fine for VGA and lower resolutions. And when it came to pre-VGA standards like CGA, .42 or .43mm was fine.
So generally speaking, lower was better, and .28mm was what everyone looked for. But prior to SVGA, it was relative. You could get a .31mm dot pitch CGA monitor but it was overkill. I thought it looked better, but was it worth paying a 25% premium? Most people didn’t think so.
Inconsistent dot pitch on pre-VGA monitors
Companies didn’t necessarily advertise dot pitch on monitors before VGA became commonplace. This can make it difficult to track down dot pitch specifications for earlier monitor types. Frequently, you don’t find it anywhere in the user manual, you have to find a service manual. And then, the information you find is inconsistent. Take the IBM 5153 monitor, for example. Sometimes you read that it had a 0.42 mm dot pitch. Sometimes you hear it had as low as a .31 mm dot pitch. Who is correct?
It depends on whether you are measuring on the diagonal or if you are measuring horizontally. VGA monitors measured diagonally, and it made sense to do so, because the pixels were square. But CGA and EGA did not have square pixels. They were rectangular. So if you measured horizontally, you got one number. If you measured diagonally, you got a different number.
Generally speaking, 0.64 or .52 mm dot pitch was adequate for the kinds of resolutions that 8-bit computers produced. They worked well for 320×200 bitmap displays. That’s why a Commodore 1702 has such a ridiculously high dot pitch and yet got away with it. And .64mm was fine even for PCjr/Tandy games that ran at 320×200, and even for MCGA games. But to display clear 80 column text and 640×200 graphics, you really needed .42 or .43 mm dot pitch.
The early VGA standards with 640×480 graphics needed .39 mm. But there were budget VGA displays that used inadequate picture tubes, sometimes even .52 mm. It produced a display, the display just looked fuzzy.
Eventually the industry stabilized and fuzzy low budget monitors disappeared. If you priced them low enough the market might forgive you, but some retro enthusiasts believe delivering fuzzy monitors with inadequate tubes at too high of a price contributed to the downfall of Tandy computers.