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Poser - OFFICIAL F.A.Q (Last Updated: 2024 Dec 01 9:20 pm)
I'd imagine the refresh rate was too low on the CRT... I wanna claw my eyes out if it accidently gets set to 60hz by a game or something!! I usually keep mine at 100hz and no problems!! I need a nice new LCD too.... maybe after Christmas!!
Gerard
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CRT screens can flicker at a rate of speed that humans can't consciously notice -- but it's there nonetheless. The flickering has no effect whatsoever on some people, while it can cause headaches in others. IIRC, I've even heard of it making some people sick. The effect is so bad for certain individuals that they can't (or at least they couldn't, prior to LCD's) use a computer.
I've heard of a very tiny percentage of people being similarly affected by fluorescent light bulbs / tubes.........which would be a serious handicap into today's world.
The flashing red eyes on a cartoon dragon sent a large number of television-watching Japanese children into a catatonic state: while at the same time having no effect on other children -- demonstrating that such sensitivities are a thing which varies widely from one person to another.
I posted an OT topic several months ago about a 'nonlethal weapon' that's currently under development for use by the military and police -- a flashlight that makes people sick.
http://www.foxnews.com/story/0,2933,292271,00.html
But I wonder if it'll be the same as with other light-sensitivity issues: where some people won't be affected by it at all?
I can relate to the refresh rate/fluorescent lights scenarios. I now have an LCD monitor which causes me no problems. I have photo-sensitive epilepsy which is triggered by flashing/strobes/laser lights - I'm afraid my days as a disco-granny are zilch!
I don't get any eyestrain or other bad effects at all now - and have also replaced my old CRT TV with an LCD model.
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I also get problems with CRTs if the refresh rate is 60Hz I always make sure it's at least 75Hz which doesn't hurt (if you'll pardon the pun)
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The issue with CRT's and refresh rate isn't so much to do with the actual refresh rate itself (says the epileptic); it's the phosphor decay rate. Any CRT phospor compound has is not instant on/off; it gets brighter under excitation along a curve, and darkens along a curve. TV phosphors have a relatively long decay rate; that is what keeps strobing and frame jerking from being a problem, as well as the comparatively low refresh rates. THings also change so slowly in video, that the long decay rate effectively becomes a poor form of cheap motionblur. Computer monitors have phosphors with much higher decay rates, as the displayed data can change totally in the space of a single refresh cycle. The low rate phosphors would make a CRT next to unreadable. The downside is that anyone who is sensitive to strobing due to epilepsy, eye focus or strength issues, or luminance intensities, need to tweak and fiddle with their CRT until they hit the magic number that doesn't get them. And LCD's are not safe, particularly for those with siezure conditions. Remember that they are backlit, almost exclusively by mercury vapor flourescent bulbs. As they age, they will develop flicker....and it will have nothing to do with refresh rates, as the light source behind the montior image is what will be flickering, most likely at 50-60hz, from the power line. And that just happens to be one of the 'sweet' spots for eyestrain and seizure triggering alike. And I can confirm that living with flourescents in the workplace is a PITA, Xeno. And you can't get away from them; just keep a map in your head of where every failing bulb is and try and stay out of its influence......
Change your eye focus distance OFTEN Look across the room out the window etc.
Definitely follow Wolf's advice, no matter what type of screen you have. You won't get a strobe headache from LCD monitors but you can weaken your focusing muscles by over use.
Coppula eam se non posit acceptera jocularum.
xeno, I believe the rumour about the cartoon show causing epileptic seizures in children is an urban myth, which is sometimes propagated by comedians and parodies of said cartoon (e.g. simpsons). but the use of flashing lites and words is a well-known hypnotic technique. I believe there is another urban myth about some govt. agency banning the use of subliminal advertising (flashing words on a screen), but in fact it was dropped by the ad agencies, after they learnt that flashing lites and loud noises were more effective in influencing the post-literate target demographic, in much the same way as they're more effective in conditioning rhesus monkeys, lab rats and pigeons.
I don't know if the story concerning the Japanese children was an urban myth or not -- I do know that it was widely reported in the news some 2-3 years ago. I never followed up on the story to verify whether it was for real. But of course as everyone knows: main stream media (MSM) news reporting is always totally reliable and 100% trustworthy: with no bias, distortions, or deliberate slants of any kind -- so I'm sure that the Japanese seizure news story was all true and then some .
The video clip which caused the supposed catatonic reactions is offered for download on the internet -- complete with "download and view at your own risk" warnings attached. I've never bothered with it.
I do know that seizures / catatonic reactions can be caused in some epileptics by flashing lights -- such as warning strobe lights mounted on construction signs or strobe lights on fire alarms. Other people can get migraines from the same types of lights.
I've also heard of individuals who can't play 'jump & shoot' types of video games because the games give them motion sickness. The same phenomenon sometimes happens with 'virtual reality' helmets and glasses -- which are still in their technical infancy, although they've been around for years.
Perhaps I should take a look at snopes sometime to see if the "dragon eyes" story is an urban myth.........but on the other hand: perhaps snopes propagates the idea that certain stories which are actually true........are urban myths.......
Hmmmmm....... :blink:
Quote - And I can confirm that living with flourescents in the workplace is a PITA, Xeno. And you can't get away from them; just keep a map in your head of where every failing bulb is and try and stay out of its influence......
In many of the offices that I've worked in -- that could be a very difficult thing to do --
Quote - > Quote - And I can confirm that living with flourescents in the workplace is a PITA, Xeno. And you can't get away from them; just keep a map in your head of where every failing bulb is and try and stay out of its influence......
In many of the offices that I've worked in -- that could be a very difficult thing to do --
AFAIK, all UK office lighting - if fluorescent - strobes at or above 70hz. I believe the majority are 100hz these days.
Coppula eam se non posit acceptera jocularum.
For many years now, nearly all of the lighting in the offices that I've worked in -- outside of the occasional personal desk lamp, ceiling downlight or display lighting -- is 100% fluorescent. This makes it tough on anyone with a sensitivity to fluorescent light flickering -- which all fluorescents do, even 'good' lamps.
The lamp situated over my head as I type this is visibly flickering -- rapidly. Good thing that I'm not sensitive to it.
With "green" fluorescent bulbs becoming all the rage right now, folks who have a problem with fluorescents are going to have an even bigger problem.........
I stopped using CRTs five years ago and didn't regret it for a minute. If you're spending several hours per day in front of a computer, using a good monitor, keyboard and mouse is essential! I can't understand people who buy a new quad-core SLI RAID killer PC every year but still use the same 17" CRT they got bundled with their Pentium II. I always end up buying the cheaper PC and spend more on the monitor instead. A bad computer may make you wait a little longer, where a bad monitor will make you sick.
Quote - I stopped using CRTs five years ago and didn't regret it for a minute. If you're spending several hours per day in front of a computer, using a good monitor, keyboard and mouse is essential! I can't understand people who buy a new quad-core SLI RAID killer PC every year but still use the same 17" CRT they got bundled with their Pentium II. I always end up buying the cheaper PC and spend more on the monitor instead. A bad computer may make you wait a little longer, where a bad monitor will make you sick.
Yes -- I've always thought that it's an odd thing: when people talk about "upgrading": monitors rarely get mentioned in the mix. And this is interesting because the monitor is the one part of PC that you stare at nearly all of the time.
For 3D / graphics people -- you'd think (or at least I'd think) that the monitor would be considered a key element of the system. And an element which would be worth sacrificing on other aspects of the PC to get a good one.
And Flat screen LCD Prices have Dropped so much these days another advantage is portability I am only using a Macbook intel dou core 2.16 GHZ 13 inch screen with 2 gigs of RAM BUT with my apple supplied adapter I can Display it mirrored or dou to an ACER 20 inch wide screen LCD and the beauty is that this LCD Detaches from its base and fits into a specially reinforced/padded 24x14"peice of carry on luggage along with the mac book and two 250 gig Fire wire LAcie porche drives and an ac power strip add to that the wifi acessability of the mac book and my entire "multimedia Studio" is now mobile and portable.
not all LCDs are created equal. I've had 2 PCs on my desk at work for awhile (decades). I had 2 15" monitors that were fuzzy and blurry, and over a couple of years almost destroyed me eyesight (I was nervous doin' my drivers test, they snuck an eye test into the sign test...:|
I switched them out for 2 18" monitor (I'm the cobbler's child, still waiting for 19" monitors to be cycled out for something better...;) and it's night and day.
I don't know how much good this does, but I seem to remember a strobe at about 18 cycles per second sets off seizures.
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Quote - I have had migraine headaches on and off for a long time, and I blamed too much time on my PC and bad eyes. Two weeks ago I replaced my 22" CRT Trinatron monitor that was burning out with a nice clear and bright 24" LCD. All of a sudden my headaches are gone and my eyes no longer burn. I can't believe a slightly larger monitor could help that much, but is seems to have gotten rid of my headaches. Has anyone else had a similar experience?
There are many people who have this problem with CRT displays. The problem isn't so much a "low" refresh rate, as it is a "beat frequency" with surrounding lighting.
If you live in the United States where the power line frequency is 60 Hz, and Windows sets your default monitor refresh frequency to 60 Hz (very common), the lights in your room will cause your monitor to appear to flicker due to slight phase and frequency variations between independant monitor 60Hz frequency source vs. the 60 Hz line frequency. The effect is more pronounced under florescent lights (which have a very frequency-dependant light output) than an incandescant bulb (which is more "filtered" due to slow response of the heated wire).
The effects are more noticable in high-contrast regions: black text on a white background, for example.
Also, since your eyes are highly customized to detect unusual motion from your peripheral vision (a survival trait - think of lions attacking you from the side), you can easily spot a 60 Hz CRT monitor by turning you head slightly away from the monitor and catching the flicker through your peripheral vision.
I can almost instantly spot when somebody has their monitor set at 60 Hz. I have never been wrong in detecting one yet, either.
LCD have a much slower frequency response than a CRT, so the flickering effect is minimized on an LCD monitor set to 60 Hz than a CRT at 60 Hz
My CRT was a flat-screen 22" Trinatron and was quite expensive when I got it, but it was also getting old when I replaced it. I only started getting the headaches in the last year so I think it was going bad. It was obviously dying when I replaced it. I never thought of the refresh rate. I never even checked that. Thanks everyone for such helpful info!!
Hi Drifterlee,
Glad to hear the new LCD helped you!
I run an LCD as well these days. If I use a CRT monitor it has to be running at 75Hz or higher in regards to the refresh rate.
Anything below that and I can see the screen rolling or refreshing. Drives me nuts.
I get migraines as well - Have for over 10 years.
I found that chocolate or anything that has serious artificial colors in it (candy like Bottle Caps or Razzels or cereal like Apple Jacks or Fruit Loops) will give me a migraine.
I've stayed away from stuff like that recently and havent had a migraine in several weeks. I was getting 1-2 migraines a week for a while.
Its always great news to hear that someone has found a cure for their migraines. They are really bad news for sure.
All the best,
Clint
On my own 19" CRT (now semi-retired to second-monitor status) even 75Hz isn't enough, my own comfort threshold seems to be 85Hz.
Quote - Also, since your eyes are highly customized to detect unusual motion from your peripheral vision (a survival trait - think of lions attacking you from the side), you can easily spot a 60 Hz CRT monitor by turning you head slightly away from the monitor and catching the flicker through your peripheral vision.
And a good thing it is too! Perhaps lions aren't an everyday threat nowadays but it's comforting to know that we are so well equipped to detect a 60 Hz CRT monitor executing a flanking manoevre. ;->
Quote - I can almost instantly spot when somebody has their monitor set at 60 Hz. I have never been wrong in detecting one yet, either.
Me too, and I always have a compulsive, evangelical desire to change their refresh rate for them, but I've learned not to mess with other people's computers uninvited. If anything goes wrong even weeks after you touched it, like hard drive failure, a noisy fan, a jammed key on the keyboard, dead mouse etc they'll be utterly convinced the change to the refresh rate caused it. :-)
Quote - I have had migraine headaches on and off for a long time, and I blamed too much time on my PC and bad eyes. Two weeks ago I replaced my 22" CRT Trinatron monitor that was burning out with a nice clear and bright 24" LCD. All of a sudden my headaches are gone and my eyes no longer burn. I can't believe a slightly larger monitor could help that much, but is seems to have gotten rid of my headaches. Has anyone else had a similar experience?
A monitor can definately make or break a string of headached. It mostly has to do with eye strain.
on a crt things like "dot pitch" and "refresh rate" were quite important. You wanted a low dot pitch and high refresh rate to minimize headaches. In my case, I looked for .23 dot pitch, and 85Hz or higher refresh rate.
I find LCD's lot more friendly when it comes to headaches. They seem easier on the eyes. But with those I'm also finnicky about high quality. Otherwise, I'm likely to get a headache!
Also, if you don't have a pair already, talk to your optometrist about special glasses for the computer. They are usually really fine tuned for typica monitor to eye distance (1.5 to 2 feet), and their goal is to reduce eye strain (headaches, dry or burning eyes)
HTH :)
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Everyone overlooked the obvious point that, by and large, CRTs are generally bulkier and heavier than their flat screen conterparts. It stands to reason you'd get more of a headache if a CRT fell on you.
HTH.
Coppula eam se non posit acceptera jocularum.
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I have had migraine headaches on and off for a long time, and I blamed too much time on my PC and bad eyes. Two weeks ago I replaced my 22" CRT Trinatron monitor that was burning out with a nice clear and bright 24" LCD. All of a sudden my headaches are gone and my eyes no longer burn. I can't believe a slightly larger monitor could help that much, but is seems to have gotten rid of my headaches. Has anyone else had a similar experience?