What Resolution Setting for 19" CRT?

Conventional wisdom used to be that you wanted a 1:1 representation on the screen so that you could take a plastic ruler and measure off the screen, and that would be completely accurate. Unfortunately, a 1:1 on a 19" screen is an odd size. The best you can get, by setting the resolution to 1024 by 768, is a 17.72 inch diagonal picture and a small black border.

1152 by 870 will give you a picture that wants to be 20.05 inches diagonal. But all this assumes that you want to measure off the screen and want everything "life size".

If you go more pixels on the screen (and your display can still show them) you start to have to increase the font sizes you use for display, and then you start to get unexpected word-processor results. But so little seems to be done on paper these days that i wonder if that matters.

I think a lot of users have thrown the 1:1 "life-size" notion out the window, but I have not heard whether there is some other rule of thumb that has replaced it.

The resolution of Mac screens is not directly comparable to a PC, as the Mac uses square pixels and older PCs do not.

The "refresh rate" number is the number of times in one second that the screen is repainted. Numbers above 75 Hertz are desirable, because the threshold of perception for flicker detected by most users is less than 75 Hertz.

The size may vary with the refresh rate in some displays as the electronics in the display works harder and harder to keep up with ever higher requested rates, eventually failing to draw the screen as fast as you have requested and kicking out to avoid damage. This is completely a side-effect, NOT an intended feature.

At 1024 by 768, a picture 14.2 wide by 10.6 tall should be displayed at the Macs default 72 by 72 dots per inch. If your display shows a picture larger than that size, its controls should be adjusted. This adjustment will result in a black border, but objects and text will be show at life size on the screen, and printed sizes will match perfectly (unless you choose to scale them during printing).

1152 by 870 should produce a picture 16 inches wide by 12.083 inches tall, which may be slightly larger than the nominal visible are of your display. Again, if your displayed picture is not this size, the "correct" thing to do is adjust your screen controls until it is that size.

Given that LCD displays are rapidly approaching 100 dots/inch, I have been hoping that some sensible "rule of thumb" concerning screen resolution, print resolution, life-size measurements, and related issues would come forward. If any readers can add light to this issue, I would find it very helpful.

For refresh rate, use the highest value available.

On the 17-inch CRT display, 1024x768 or 1152x870 would probably be best.

On the 19-inch CRT, 1280x960 would be good, if the G3 can do it. I have 19-inch CRT that can do 1600x1200, but I use it at 1280x960 most of the time.

How do I choose the best resolution & refresh for this set-up?

I try the available resolutions and pick the highest one that displays comfortably and without fuzziness. Color depth may be a consideration. With some video cards, at higher resolutions, Colors may only go up to Thousands instead of Millions. If you need Millions of colors, use the highest resolution that supports Millions.

Then I make sure the refresh rate is at the highest available setting for that resolution.

If you go through older Mac manuals, they tell you to set the screens for certain resolutions and then adjust the screen controls to get specific sizes. When I was designing printed forms, I computed the sizes based on "life-size" at 72 dots/inch, which was the standard at that time. There does not appear to be a changeable setting in Mac OS for dots per inch, but older software (such as OS 9 Apple System Profiler) reported the assumption that your screen was set for 72 by 72 dots per inch.

Since these are the computed 72 dots/inch numbers, they would apply to any Mac display. The 17 inch display, adjusted as Apple specifies for 72 dots/inch, leaves a 3/8 inch black border around the picture, Most users find this completely unacceptable, set the 17" display resolution higher and wave goodbye to "life-size" once and for all.

There does not appear to be guidance from Apple in this regard any longer. Screens you buy today are capable of higher resolutions, and most users want the highest resolution for the sharpest picture, rather than my numbers for "life-size". If there is a way to set the software-perceived dots/inch, I do not know what it is.

The limit of what the display can do will be quite a bit higher than 72 dots/inch. Often the CRT tube has a maximum resolution higher than the display electronics can reach. Numbers like 0.28 mm/dot were common. Really fancy display may go up to 0.25 mm/dot. Trinitron tubes use colored stripes rather than discrete dots, so only their horizontal dots/mm is important.

The original manufacturers specs on the display will tell you how high it can go.

Whether you want to stop at "life-size" 72 dots/inch or press on for higher clarity depends on the work you will be doing with your display. The assumption which used to be built in to the Mac software was that the screen was at 72 dots/inch, and the printer was at 300 or 600 dots/inch (or higher for typesetters) and how big you had to make things was easy to compute, everything scaled nicely, and "What you see is what you get" to the nearest 1/600 inch.

Today, many users simply set the resolution higher a step at a time and when the screen turns black, they don't say OK and it reverts to the previous setting. Then they adjust the text sizes for emails and web pages, so that they can read the text, and live happily ever after.

That was japamac's recommendation, and it is a good one unless you require perfect size agreement between on-screen and print.