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Advice needed: least eyestrain

  • CRT Monitors
  • Monitors
  • Peripherals
Last response: in Computer Peripherals
March 28, 2003 4:36:58 PM

I am planning to get a new PC, and while I'm at it I decided I might as well get a new monitor. I think I'm going to stick with SONY since in the past their products are almost always satisfactory. I want a 17" CRT monitor that will give you the least eyestrain, performance and the others are secondary requirements, safety to the eye is what I'm looking for the most. So can anybody give me any advice? I've checked their website and I think the STYLEPRO Series 17 FD Trinitron® CRT CPD-E240/B looks good.

More about : advice needed eyestrain

March 28, 2003 9:23:30 PM

My advice is this:
A) Get a monitor with a white/ beige bezel (less contrast between bright screen and it)
B) Get a totally flat monitor so certain issue with glare are better
C) Run it at a comfortable res (1024x768 usually, tho 1280x1024 is fine too if you're not straining to see it)
D) Make sure refresh rate is high, above 85Hz, and even better is above 100Hz

Hilbert space is a big place.
March 29, 2003 4:27:37 AM

umm i heard that black monitprs were better becasue then you can reduce the brightness of your monitor.

but i don't know where i got that from so white ones might be better.
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March 29, 2003 10:10:02 AM

Go with the black monitor. Your eyes focus and dilate according to the brightest object in your field of vision. In a well lit room that is often the plastic bezel of a white monitor, not the display. With a black casing you can often turn the contrast down a fair bit, taking advantage of the lower output to get better focus.

As for the other suggestions...

Most people can't see flicker on a monitor above about 68 hz. Any refresh setting of 70 or better will give you a steady state image that's easy to look at. You don't need 100+ refresh rates unless you are into some kind of extreme gaming and at the lower rates the monitor will run noticeably cooler.

Flat screens do reduce glare, but they also tend to have focus problems in the corners. Most of the better manufacturers (NEC, ViewSonic, KDS) include circuitry to compensate for this.

I suggest you avoid monitors with Diamontron and Trinitron tubes. These CRTs have 2 lines across them that you can't eliminate/hide no matter what you do... some people seem not to care, but they drive the rest of us nuts.

The real thing to watch out for is Convergence --the way the Red, Green and Blue guns come together to make white-- even very minor convergence errors and land you in headache central if you are doing anything with high contrast ratios or looking at white text a lot.

Second to convergence is Focus. A blurry monitor is almost a guarantee you will end up needing glasses in a few weeks.

Now... here's the killer.... both Convergence and Focus vary not only from one model/maker to the next, they vary between identical monitors. If it's at all possible, preview the monitor before you bring it home.

--->It ain't better if it don't work<---
March 29, 2003 4:10:22 PM

Black monitors cannot meet TCO 99 regulations because of the eystrain they cause, among other things. Try looking at a monitor from the corner of your eye- even at 75Hz you'll notice the flicker.

Hilbert space is a big place.
March 29, 2003 7:52:05 PM

1) I don't care about TCO-99 or whatever.

Our eyes focus and dialate on the brightest object in our field of vision. If that is not the data display, it's going to look out of focus and we will "pull" our vision trying to focus upon it, causing eyestrain. To a one, the black case monitors cause my customers considerably less eystrain. I get fewer than half the focus complaints about black cased monitors than I do about white case ones. I've even got people who don't need their glasses when working on the computer since switching to black cases. The dark case removes the monitor from your field of vision allowing you to more comfortably focus on the display and not on the case.

2) "Flicker" is not a fixed phenomenon.

Lets do a little math... put a monitor in a room with flourescent lighting (i.e. just about every office). The flourescents flash off and on 120 times a second... 120hz. At 100 hz the "beat frequency" between the lighting and the monitor is 120 - 100 == 20hz flicker rate... clearly visible. At 70 hz it's 120 - 70 == 50hz ... far less noticeable.

Take out the flourescents and put in standard light bulbs and the situation changes drastically. Incandescent lights do not strobe, they glow more or less evenly. With overhead incandescent lighting it is likely you would not see flicker at any refresh over about 65 or 68hz.

Plainly specs and standards dont't tell the whole story. Monitors do not exist in a vaccuum...

I appreciate your points and taken soley on specs, you are absolutely correct... In a pure environment where the monitor is the only light source (i.e. a dark room) there are a few people who can see 75hz flicker. But there are many other factors that influence one's use of this equipment... lighting, state of vision, concentration, nearby windows, etc. all influence what a computer user sees.

Standards are wonderful things, until you place them in the real world.

--->It ain't better if it don't work<---
March 29, 2003 10:10:40 PM

With regards to the flicker, why should one have to suffer in that part of time they *shouldn't* see it and in some cases they *should*. Why not get a monitor which you won't have to worry about flicker. I don't use flourescent lighting. "With overhead incandescent lighting it is likely you would not see flicker at any refresh over about 65 or 68hz." That's your standard, and I say it's wrong, but I see flicker at the rate. I see flicker at 85hz even.

Hilbert space is a big place.
March 30, 2003 3:58:43 AM

Well then, the answer is that you aren't part of "most people"...

I'm running my system right now as I described... 70hz, overhead incandescent lighting and not a trace of flicker.

Why do you see it?

Who knows... maybe your eyes respond faster than average...

All I'm saying is that <i>most</i> people wouldn't see it.

--->It ain't better if it don't work<---
March 30, 2003 4:03:40 AM

Well.. so long as the specs are accurate (Viewsonic is known to exaggerate a bit :smile: ) yeah, I'd say it's probably a good monitor. I've a couple of customers using Viewsonic and they've never badmouthed them to me...

As always, see if you can find one in a store so you can "see before you buy".

--->It ain't better if it don't work<---
March 30, 2003 4:05:07 AM

Ok, I'll give you that, but none the less, the response time of our eyes, if you will, varies day to day upon many factors; how tired you are, etc., so that I just think people overall will be more comfortable with a refresh rate that they will never notice flicker on.

Hilbert space is a big place.
March 30, 2003 4:41:49 AM

My gosh, you are persistent aren't you?

Ok, one last time... I've *never* seen flicker on any monitor running 70hz or better. Most of my 200 or so customers are set at 70 or 75 and I get almost no complaints of flicker. (And yes I do ask if they are satisfied with their displays.)

There is nothing <i>wrong</i> with running "a refresh rate they will never notice flicker on". Lots of people run 85 or 100hz when they don't really need to... aside from a little wear and tear on the horizontal output transistors (which do run hotter at high refresh rates) no harm is done.

My point is that just because you can see flicker at 85hz you can't assume everyone else does... because we don't.


--->It ain't better if it don't work<---
March 30, 2003 9:01:27 AM

hey teq i have to say that i see flicker at 75Hz(looking straight at the screen),
i even see it at 85Hz (from the corners of my eye)

sure 75Hz flicker is not a big problem and is only noticable when trying to look for it.
but i can still see it. (p.s. i have never set a monitor over 85Hz so wouldn't know if i see flicker that high)

but looking around a showroom at monitors and tvs i could pick out the refesh rates.
e.g. some tvs are running at 100Hz flicker free well i could instantly tell those ones from others that were only doing 50Hz or 60Hz, and monitors at 65Hz stand out like a sore thumb. i can see 75Hz flicker easily (but have yet to see anyone who actually has it set to 75Hz).

and 85Hz isnt perfect but its the lowest i can personally put up with. any lower and i change it down in resolution till i can get 85Hz. LOL

so perhaps some peoples eyes are much more sensitive to these things I DON'T KNOW.

but yes 75Hz is OK.

March 30, 2003 2:57:38 PM

Now we have 2 people who can see 75Hz. Perhaps your eyes aren't like the rest or u deny you see it? Here's the issue with 200 customers- most do not know much about computers, so even if they do notice flicker from time to time what can they do? The TV flickers too, so they accept it. This is the case with many of my friends.

Hilbert space is a big place.
March 30, 2003 5:33:59 PM

Hi there!

How's the monitor doing?

About the flicker thing...
I'm not going to get into a long discussion of this.

As I already explained, there's nothing wrong with running higher rates. All I was saying was that most people don't see much flicker above about 65 or 68hz. When I run into someone who does see it, I just increase the refresh rate... it's really not much of an issue at all.

--->It ain't better if it don't work<---
March 30, 2003 5:34:38 PM

Have you considered decaff? :smile:

--->It ain't better if it don't work<---
March 30, 2003 9:17:23 PM

lol, no coffee for me- just Pepsi, Mountain Dew, and Pepsi Blue:) 

Hilbert space is a big place.
March 31, 2003 2:18:48 AM

Yo Teq, can you give me some tips on how to pick out a good monitor? I'll be buying it in a nearby computer store :)  The article in THG isn't clear enough.
March 31, 2003 3:10:23 AM

No problem...

First thing is to decide between LCD and CRT...

LCDs are getting better and cheaper all the time and they eliminate the three biggest bugaboos of CRT monitors: focus, convergence and linearity. Since the LCD image is produced by individual triads in fixed locations rather than a scanning beam they can't go out of focus, can't have bad convergence and the linearity is good enough you can actually use a ruler to check the relative sizes of things.

CRTs are faster and when well adjusted they can be as well focused as an LCD (although it is rare to see this in a production model). You won't get the "smearing" effect you sometimes see when things move on cheaper LCDs, which may be an advantage in fast paced games or watching videos. (but LCDs are rapidly catching up!)

Technically the CRT system is about 100 years old. Find an antique radio from the early 1900s with the "magic eye" tuner in it and you've found an early use of CRT technology. Of late I've been making quite the project of getting all my customers switched over to LCD "flatpanel" displays and so far nobody's bitching at me :smile: .

Without getting too deeply into how they work...Should you decide on a CRT display there are a number of things you should take into account:

1) Trinitron and Diamondtron CRTs have two lines across them that you can't get rid of and can't hide. These are actually voltage equalization wires, part of the aperature grill they brag about, placed right in the path of the electron beams. Some people just shrug and accept them but others find them extremely annoying. It's bad tech used to cover a bad design and unless there is some overriding factor, I'd suggest you pick a different monitor.

2) Factory adjustment. CRT monitors have a number of factory/repair level adjustments inside. Accurate setting of these can seriously improve display quality. Unfortunately, most factories (esp. those who've transitioned from television sets to monitors) don't take anywhere near enough time on these adjustments. So, you should expect to see highly variable display quality, even between monitors of the same make and model.

3) User adjustment. On CRT monitors, you want a certain minimum set of user adjustments: brightness, contrast, colour balance, h/v sizing and centering, rotation, pincuishion and corner pin. On larger monitors you also want convergence adjustment. (Nothing annoys me more than a crooked, off center image you can't fix.)

4) Case Colour. As I've already explained, black or charcoal monitors appear to provide better focus and brightness. There are designer coloured monitors out there but these will have the effect of skewing your colour perception and should be avoided.

The things that will affect your satisfaction the most are Focus and Convergence. Unfortunately both of these are factory adjustments and can vary over a wide range, even between monitors of the same make and model.

The focus is obvious, nobody wants to look at a blurry image.

Convergence is a bit more complicated. CRT images are formed by scanning electron beams across the screen in rows. As these scan they hit small dots of coloured phosphor on the screen causing them to glow. All colours are produced from combining tiny dots of red, green and blue. Hense there are 3 beams used. For this to work correctly all three beams must be perfectly coordinated so that they land on the same colour "triad" at the same time. To fail to "converge" properly will produce (at minimum) fuzzyness or (at worst) distinctly coloured shadows under objects on your display.

To check convergence you generally need test patterns but, for a quick check, you can always pop up a DOS box and use ALT-ENTER to make it full screen. Do a DIR command and look closely at the displayed text. Are the edges nice and crisp? Are the individual dots clearly visible? Do the white characters have red, green or blue, shadows under them? Basically, anything you see on a DOS screen that isn't a razor sharp white character is a problem. If it's all nice and sharp the odds are the convergence is more or less OK.

If it is at all possible, I suggest you check the actual monitor you will be taking home before you spend your money. If there are problems you don't have to go shipping the thing to China or lugging it back to the store. An interesting side effect of this is that often you can save a few bucks by buying the one on display...

Hope this helps...

--->It ain't better if it don't work<---
April 3, 2003 6:16:57 AM

Just a quick two notes (that should be two seperate posts to two different people, but I'm too tired right now):

1) I believe people can see flicker out of the corners of their eyes more than when looking right at it because of the differences between how rods and cones work in the eyes. Practically, I think it's best to use whatever feels good and is in line with what your eye doctor recommends. Here's my GUESS (just a guess): if you can see a monitor flickering out of the corner of your eye, but not when looking at it dead on, it's refresh rate is probably fairly close to your detection of flicker ability straight on. If you can't see it flicker even out of the corner of your eye, it's refresh rate is probably significantly faster than the viewer's ability to detect flicker straight on. Just my guess. This is assuming a non-flickering light source that is not interfering with the whole process.

2) Teq, your theory on the strobing ("beating") effects on flourescent lighting is more or less correct to my knowledge, but your math and general paradigm are way off. It's not the difference between strobe rates that is the issue. It's the effect of two strobing sources on each other. Things to think about: if you have 2 sources of light both strobing at 120Hz, what will be the effect? What if the synchronization of the strobes is aligned? What if it is not? What if one of them is 60Hz, and one is 120Hz (a perfect multiple)? What about one at 80Hz and one at 120Hz (not a multiple, but shares common mathematical factors)? What about one at 119Hz and one at 120Hz? In each case, think about how many cycles will overlap over time (and remember that time does not equal just a single second). We must also think about whether it is good or bad for them for strobes to intersect. As you can see, simply subtracting the numbers from each other has absolutely no meaning. It's much more complicated than that. My recommendation, based solely on my personal experience (sample size=1) is to make sure you use monitors in light that is non-strobing. That largely avoids the issue.
April 3, 2003 7:05:26 PM

Excellent points both, Goatcheese...

For the first point...

That flickering we see from the corner of our eye could well be unconcious darts of the eye as we try to see without seeing. It could also be that our peripheral vision is more of a motion detector than a true sense of sight... a hang over from the caveman days when we needed more caution about being snuck up on.

Whenever this topic comes up I am reminded of the #1 funniest service call I've ever been on. Years ago, one of my customers complained that her monitor was "jumping around" as she worked on it. When I got there, I couldn't see it and she even said it wasn't doing it while I was there. So I took the monitor with me, gave her a loaner, and used it myself for a few days... it worked fine. But, then she complained that the loaner was doing it too. So I went back out to re-trade monitors and there she was with a carrot stick in the corner of her mouth, munching away while she typed. As soon as I went to her desk she quickly finished her snack and we traded monitors. On the way out the door I noticed she was munching again. So, when I got home I got a carrot and bit the thing while looking at my monitor and it looked like it lost vertical sync! To make a long story short, I repaired her monitor by suggesting a softer snack food. The vibration of biting the carrot was jarring her eyes... Last time we spoke, about a year ago, the problem had not returned and she was still joking about the whole thing.

There are SO many things that affect our perception...

On the second point...
I am indeed aware of the complexities of waveform interference and phase relationships (you don't get far in amplifier design without learning something about it). I wasn't treating the subject simplistically. I was trying to offer a somewhat non-technical explaination. Perhaps I over simplified and if I did I aplogize for that.

--->It ain't better if it don't work<---
April 7, 2003 4:08:44 AM

I see no flicker at 60 hertz with flurecent lighting. The corner of the eye thing you were talking about is true, peripherial vision is terrible to actually SEE things with but it is fantastic about detecting motion. Try looking straight ahead and concentrate on something in your peripherial vision. It is hard to pick up the details on what it looks like. now move your hand in your peripheral vision. notice the differance? it is a lot easier to focus on the hand than an object that is not moving.

Pull the lips over the gums look out testicles here I come! -What is that from?