Screen Size and Resolution

I have yet to see a 15" monitor that looks crisp at 1024 x 768 - or a 19" one that does justice to 1280 x 960 or 1280 x 1024 resolution.

Yet these monitors are often rated for these settings, and often even higher ones.

What's going on here?

Quite simply, we're looking at the difference between how many dots per inch the computer is trying to display and how many dots per inch the monitor can show before they start running into each other.

A decent monitor today will have a horizontal dot pitch of about 0.22 mm. That is about 4.5 dots per millimeter or 115 dots per inch. Anything higher than that will be fuzzy, since the monitor will be trying to display more than one pixel per screen dot. (For more on dot pitch, see Monitor Dot Pitch.)

My 19" Optiquest V95 monitor has an image about 13.5" wide, so you'd think it should be able to crisply display 1550 pixels at one pixel per dot. Yet if I set it to 1600 x 1024, it's fuzzy. And when I step back to 1280 x 960 or 1280 x 1024, it's still fuzzy. Yet 1152 x 870 seems crisp.

Weird, isn't it.

Obviously, there's more to crisp display than simple dot pitch and resolution would indicate. That doesn't mean that dot pitch isn't a good indicator of screen sharpness, only that it doesn't directly predict the maximum sharp display setting.

In reality, you have to be at 1.3 to 1.5 dots per pixel before the screen looks pretty sharp. In the case of my Optiquest, that explains why 1280 dots horizontally doesn't quite cut it, but 1152 works very nicely.

Looking at another example, while my 17" Nokia 447z was in the shop (third times!) and before I picked up the Optiquest, I used a 15" Compaq Presario v410 monitor. It claimed to support some high resolutions, but the highest one that looked sharp was 832 x 624.

The Presario has a dot pitch of 0.28, which comes to about 0.22 horizontally. It can display a fuzzy 1024 x 768. Again, a 10.5" horizontal dimension predicts a sharp 1200 dots, but it just doesn't work out in the real world.

Instead, we seem to be at that ratio of about 1.4 dots per pixel for a sharp display. And the same goes for most 15" displays, which looks great at 800x600 but fuzzy at 1024 x 768.

Studies have shown that when scanning images for printed output, the image should be scanned at 1.3 to 1.5 times the final resolution - or it will look fuzzy. The same principle is at work here.

As a general rule of thumb, a good monitor will have a horizontal dot pitch somewhere around 0.22 (or a diagonal dot pitch of 0.25-0.28). Using the square root of 2 (1.414) as our factor, to achieve a specific sharp resolution, you must have a monitor of a minimum size.

Keep in mind that viewable is measured on the diagonal. This is not the full size of the picture tube, and these numbers assume about 0.22 horizontal dot pitch. This helps explain why a 10" VGA display (seen in some stores) can support 640 x 480, but the once-common 15" (13.8" viewable) display isn't sharp at 1024 x 768 - it's two inches too small.

My old Nokia monitor worked fine at 1024 x 768, but it simply didn't look good at any higher setting. My Optiquest 19" is great at 1152 x 870, but doesn't quite cut it as 1280 x 960. Yet the Sony monitor I used at my last job, a 21" screen, supports 1280 x 960 and 1280 x 1024 beautifully.

How I Work

I spend a lot of time switching between email, page design, my browser (usually Internet Explorer, but sometimes something else), and a URL manager. I find it works best if I keep my emailer on the left of the screen at about 600 pixels wide and nearly full screen height, the URL manager on the right at close to full screen height (I visit a lot of sites daily), and move the browser and design (Claris Home Page) windows as necessary. Much of the time I'm moving between Home Page and my browser, so it's nice if those windows can be next to each other with little or no overlap.

Because I try to design my sites to work well on older Macs and PCs with small screens, I keep my browser window at about 640 pixels. To work with a browser window and design window side-by-side, that calls for a 1280 x 960 monitor. That's what I had at work, and I loved it.

But nowadays I use an Apple PowerBook G4 with an 1152 x 768 display, which meant a bit more overlap between my windows. Not only does this look cluttered, but it takes a bit longer to switch between applications when more of the screen needs to be redrawn.

Much as I'd love a 1280 x 854 screen like the newest PowerBook G4 sports, they're pretty expensive. Some day....

Before buying the PowerBook, I discovered that 19" was a bit less than I liked, but it was a huge improvement over 1024 x 768 on the 17" Nokia. There was a little overlap, but a lot less than there had been. And with a little creative resizing, I could have my browser window and Home Page windows next to each other.

I could work smaller, but I lose efficiency below 1152 x 768.

Your work habits will determine how much screen you need. And once you know that, you can use the table above to decide the minimum viewable area you need to get it.

What About LCDs?

About now, some of you may be wondering, "What about laptops? Do they suffer from the same problems as conventional monitors?"

Happily, the answer is no. A dot on a flat panel display is a dot. Period. In fact, flat panel displays will look fuzzy at any setting other then their maximum. A PowerBook G3 with a 14.1" 1024 x 768 screen is a thing of beauty, but 800 x 600 and 640 x 480 look fairly bad.

The only ways to have sharp resolutions other than the maximum are for the maximum to be an exact integer multiple of the lower resolution (e.g., a 1280 x 960 screen displaying 640 x 480) or to only use a portion of the display to show the lower resolution image.

This gives flat panel displays several advantages over traditional monitors, along with two disadvantages.

Advantages

• tack sharp at their designed resolution
• smaller display remains sharp (14.1" diagonal provides a sharp 1024 x 768, where a CRT must have a viewable diagonal of at least 15.8")
• smaller footprint
• very low power consumption

Disadvantages

• fuzzy at any resolution other than the maximum (with the rare exception of exact integer multiples)
• expensive, but getting more affordable

For now, traditional monitors are the way to go unless you need portability or have a generous budget, but flat panel displays continue to drop in price and increase in resolution.