Back in the old days of computers (say the late 70's and earth 80's) When people where finished at working at a computer all day, their eyes where all bugged out and had to use eye drops. This was because the refresh rate of the monitors in those days was something like 20 hertz (so a lot of flicker).

So the refresh rate of a monitor is how many times it refreshes itself. The hertz is how many times per second it refreshes. The default refresh rate a common Windows computer is 60 hertz (The same as a North American NTSC TV) This is way too low for common use (espeicly if you're doing something where you have to concentrate on the screen for a long time, with high contrasts)

You might be surprised, but it can seriously damage your eyes. This is partly why LCD monitors are so popular, since instead of a tube with a electron gun shooting photons at a screen, it's a grid of Liquid Crystel Diodes.

To change a element on the screen, it just changes the pixel. Those monitors are the same sort of thing that you see on a calculator, except that it shows colour, and there is a lot more pixels.

Since LCD's are totally digital, there's no conversion in a DAC, that is if you connect your monitor into interface that is totally digital (such as DVI) plugging your LCD monitor into a VGA video card, it may be clear, but it would be a lot clearer and more responsive plugging it into a DVI port (Since there is no extra interface with a DAC)

Most of us already know this, especially me since I took Computer Maintenance A+ last school year.

^Baseless assumption that everyone knows this kind of information, especially when most people know that staring at a computer screen/TV screen for long periods of time is bad for their eyesight, but don't know the actual reason WHY. And yes, there is most likely someone on FH who did not know that, and PTK has just enlightened them.

I find setting my monitors refresh rate lower than 100 hz hurts my eyes. Everything is clearer too.

Plus you have to take in account the screen resolution you're using and the monitor you're using. For 14-15" CRT monitors, anything higher than 1024 x 768 pixels will fuck up your eyes. If you need higher than that you should something a little bit bigger, say 17" however, with a LCD monitor this isnt as much as a issue because it's not directly radiating on your eyes.

Plus, how you're using the computer and the monitor affects how it will affect your vision. You shouldnt use a computer in a dark room. Plus speaking of that, the brightness and contrast you use on your monitor can affect things too. Anything too low or high can cause eye strain. How you sit, the angle the screen is to we're you're typing. They are all factors.

Plus how long you're using you're PC. Having your eyes focused on one object for so long can cause problems with the muscles in your eyes. This why people suggest that after every hour of working on a PC to look away and focus on something else in the room for a few minutes. I know this first hand. I've been using computers a lot since I was 13 and I have vision problems. Undiagnosed. But I looked it up. It's called computer vision. or whatever.

So yeah. Sorry if I'm telling you stuff you already know. I just posted this because I couldnt think of anything to post. And I was thinking about it because I sit at school in front of a computer all afternoon

http://www.100fps.com/how_many_frames_can_humans_see.htm

Probably all you need to know about it.

That's what I was trying to get at N0th1n. When you're looking at a monitor refreshing at 60 hz you are looking at quite a bit of blank frames, it's fast enough we dont percieve it. If you slowed down time and looked at that monitor, at times the screen, or parts of it will be totally black. This is partly the reason for the eye strain.

I'm used to 60Hz... Only if I'm REALLY tired then it'll be bothersome to me.

More likely the strain is from looking at something that actually IS lights, of various colours, continuously over a long period of time, rather than what you usually see which is the reflection of light.

Also, apparently when you look at monitors and tvs and such, you tend not to blink as frequently, and, like with reading, you are focused on a single distance, so your eyes do not adjust to various amounts like they usually would. This also causes strain, and the general recomendation is to look away from the monitor or tv every so often (at least every hour if not more) and focus on something distant for a while till your eyes adjust back and such.

Seizure inducing, then? ;)