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Comment by bserge | Hacker News Reader

My eyes used to hurt a lot on CRTs. A few hours every day in front of one and I could not go outside without sunglasses, anything would make my eyes hurt.

Everything was fine if I went a week without using a computer.

With LCDs, that's not a problem anymore, and I like it.

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I guess most people can’t see the flicker on a CRT set at 60Hz, but I can. It’s especially bad in a room with fluorescent lights. First thing I’d do upon sitting down at a new computer with a CRT monitor was to bump up the refresh rate to 75Hz so I didn’t get a headache.

Taking standardized tests in the early 2000s on locked down computers in fluorescent-lit test centers was torture.

Yeah, I used the highest refresh rate I could force, usually 75-80 Hz. Some monitors could handle 90, and it made a difference, but it was still worse than LCD PWM flicker.

most people absolutely can see the 60hz, the effect is simply subtle. if you look at a CRT from an angle it's more visible, or you can wave your hand in front of you and observe the strobe effect.

i definitely do not miss 60hz CRTs, they made me miserable.

I was so happy when I figured out how to switch to 60 Hz. Living in a PAL region I was stuck at 50 Hz. Later on PC I cranked up the Hz as high as it would go while still display something.

And yes, the flicker is easy to spot if you just sit in front of the screen and look just above it, prefferably in a dark room. Or wave your hand in front of it. With LED lightbulbs you can also use your phone camera, move it realy close to the lamp and if you see banding, it's not good.

I’m fine with 60 but I’m in a PAL region so all of my 90s consoles run at 50Hz. That is seriously uncomfortable to look at now and I have no idea how we all put up with it.

Presumably the phosphors in the PAL CRTs glowed for longer?

May not have been bad in the earlier sets as they would have used phosphors that persisted longer to compensate, but later on, manufacturing costs were driven down and the same tubes/coatings from 60hz sets were being used in 50hz sets, making the flicker much more apparent.

I'm using a PVM so it's high end kit, however perhaps because it also supports 60Hz they are unable to use the longer-glowing phosphors?

I found the flickering at 60HZ unbearable, but at 75HZ it was barely noticeable. My sweet spot wast at 80-85HZ. I tried until 90HZ, but you had to sacrifice resolution and past 90HZ, I didn't notice much difference.

I think for today's LCD/OLEDs 90-120hz should be the sweet spot, especially for gaming and motion. More than that is a waste of computing. (there are monitors that offer 144-200Hz refresh rates, but that is mostly a waste).

I’ve had a 240hz monitor for a while now and I wouldn’t say 144hz is a waste.

I do agree 100-120hz is the sweet spot, good balance of refresh rate and graphical quality.

I would not suggest a 240hz monitor if you are not playing competitive shooters a majority of the time.

I agree. By 'a waste', I didn't mean that it is not better, but I meant that it is a diminishing returns curve, and you will end up sacrificing a lot to achieve it (resolution and graphical quality, as computing is not free) and it doesn't feel that much better. Going from 60HZ to 120, or even 90HZ is very noticeable by everyone, even in normal 2D content. Past 120 it is like, eh, just a bit better.

Between 120HZ 4k, and 240HZ HD, I'd take the 120HZ 4k Between 120HZ 4k, and 90HZ 4k but with fully Ray Casting, I'd take the 90HZ (unless it is a competitive FPS)

etc...

BlurBusters argues even 1000Hz worth, interesting.

https://blurbusters.com/blur-busters-law-amazing-journey-to-...

But the fundamental difference is that LCDs are static. Like, if you have a static image on screen, it does not refresh. A CRT is always refreshing at x Hz.

On LED backlit displays, it's the cheap PWM brightness controllers that can be noticeable. They're supposed to pulse hundreds of times a second to maintain the brightness setting, but as you go lower, it can be noticeable and tiring on the eyes.

On LCDs, refresh rates matter only in constantly changing pictures, like movies and games.

On a CRT, you're exposed to the constant refresh flicker even if you're editing a file or reading an article.

All in all, I'm happy with LCDs. Even in games, they're enough for me, I'm not that competitive.

An LCD with 20hz won’t give you a headache - an LCD pizel is always on (but only changes on refresh).

A crt pixel is on for only a very short time, while picture results from eye’s persistence of vision (which is also why in movies CRT screens flicker)

Any kind of Motion, scrolling, movies, games... etc... refresh rate matters.

Sure, cinema movies are 24fps, and they do manage, but you are usually not 2 feet away from the screen.

60Hz wasn't really a default for long though? Most CRTs in Windows 9x era would do 75Hz or 85Hz if you didn't push them above their native resolutions.

I'm pretty sure Windows 9x defaulted to 60 Hz even when the monitor could handle more, and most people just kept the default. I recall walking past computer labs in high school, seeing row after row of blinking rectangles.

Many LEDs have an annoying flicker as well, which can be very annoying and distracting for me. Especially around christmas time, when everyone and their grandmother puts out thousands of cheap LEDs. Even when they're not trying to blink, they're still flickering. I suspect I'm sensitive to this kind of stuff because I suffer from migraines, but still, I can't imagine I'm the only one.

Christmas LEDs are technological abominations. They literally hurt to look at.

And they don't really twinkle like the heat driven, blinker style incandescent lights do. I loved to watch the pattern on the ceiling as a kid. It would change in subtle ways. Never the same, but sometimes really close.

I got a set and I am scared of them. Fire hazard. But I do run them once in a while for young ones at Xmas time. Just so they can check it out.

I have had the same feeling about early cfl lamps. Turning those on seemed to make the rooms darker and more dingy instantly

Yes! We tried to like those and had the same impression.

Amount of light seemed good, but quality was in the dumps.

I don't understand what it is about some LEDs that make your eyes hurt when you look at them.

Best way I can describe it is that my eyes can't focus on them and are constantly trying to.

I can't focus properly on bright blue things. There's a football stadium not far from where I live and its name alternates between red and blue in big text.

I know what it says but I cannot read it at night when it is blue.

> I can't focus properly on bright blue things.

No one can, for a bunch of reasons. The eye is mostly corrected for red-green wavelengths; the eye is a lot less sensitive to blue light; there are far fewer receptors for blue light, which reduces spatial resolution.

Monochromatic blue displays are an extreme UI antipattern and should not be used for anything. If combined with high luminosity, they become essentially unreadable unless close up. E.g. ultra-blue seven segment LED displays. VFDs can suffer from this, but this is also the reason why many of them use green-blue phosphors, and not blue phosphor (which would be possible).

The worst LED lights are 60Hz, very short duty cycle, very quick flash, with no diffusion. They're seemingly-infinitely small pinpricks of pure chroma flashing at an unpleasant speed. The worst are the blues.

It was impossible for me to spend 8 hours a day in front of a screen until the end of the 90s. I still have a 1999 CRT monitor and I don't have that problem. This feeling of pain in my eyes is something I wouldn't want to experience anymore. There are times when I miss my dot matrix printer.

This sensation may be caused by the flickering as the phosphor fades towards black before the screen is retraced. There are CRT monitors with long persistence phosphor that mitigate this, but it makes them unsuitable for motion video.

My favorite concept is that of the Tektronix vector terminals. They trace the image to a long persistence phosphor as necessary and then retain the image without retracing it by constantly bombarding the whole screen with just enough electrons for the already lit phosphor to stay lit. As a result, once the image is drawn the screen may have a little brighter black than a "normal" CRT monitor, but no flickering. I've never seen one in real life, but it seems like it would be great for ergonomics.

Check out this demonstration of "Space War" on a PDP-1 using a radar long-persistance CRT: https://youtu.be/1EWQYAfuMYw

I remember when I switched from a CRT to an LCD monitor. The difference was so dramatic I remember my head aching. For me it wasn't the brightness it was the curve vs flat. Going from looking at a curved screen for years to a flat one was a massive change.

Out of curiosity, did you ever have similar issues with flat CRTs?

I had a flat CRT TV a 30-ish Toshiba widescreen. But I was seated on a couch ten feet away so no problems there. I never had a flat CRT computer monitor.

I think my reaction was due to being so close to the computer CRT monitor. My brain had adjusted to the curve but when I got the LCD I felt like I was going to throw up I felt so disoriented. It took about a week to get over it.

Same.

A crt with refresh rates below like 60 and I could see the frames. It was torture. 120hz or more didn't seem to be an issue and its certainly not a problem since ive had lcds.

That being said it might be fun to go back for while.

While running my CRT monitor at 60 Hz recently I discovered that peripheral vision has better temporal acuity than foveal vision. Flicker is much more noticeable of things you’re not looking directly at.

I think this had a lot to do with low quality fluorescent light ballasts in offices. I agree that it seemed to happen a lot more with CRT, but I have experienced it with LCD too.

On LCD monitors, I could notice that on very low brightness settings, which was likely due to PWM flicker. I guess I'm sensitive to it.

In 2008 or so, I ended up going to a neurologist because I was getting these brutal headaches that couldn’t be resolved by my GP. They couldn’t find anything either. And then I quit my job and no longer spent my days starting at a CRT under shitty fluorescent lights, and all the problems went away. Magic!

Some people call it allergy to electricity but most of them just have problem with flickering lights. It's incredibly straining even if we don't notice the flicker.

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