Can feel with you, more or less my story also. Additionally also combinations which worked perfectly fine stoped working after update to Win7, BIOS update, graphic card driver update (happened to me with both Radeon and GeForce) or when just using different output (DVI instead of VGA). Win7 update translates probably also to a driver update.
I also think LED itself is not the issue, however when PWM is present LED is worse than CCFL.
My current theory is that aditional to PWM, there is a color dithering issue (other people here also came to the conclusion - see snowing issue or so).
Due to the fact that 99% of the screens can only do 6 bits per color (meaning 262144 colors) but manufacturers still advertise millions of colors, these additional colors are simulated by all kinds of dithering methods (spacial or temporal, but I think there are many different algorithms and implementations). Worse one seems to be the temporal one, which changes the color of a pixel in each frame (meaning at 60Hz).
Additional to this it seems that many drivers poorly implement the dithering, or the driver implementation conflicts with an additional dithering implementation on the screen side. For example I read somewhere that Apple had until 2011 or so a bug which was implementing dithering although a Cinema/Thunderbolt display was connected, which is 8 bit per color and theoretically doesn't need dithering.
Following experience confirms my theory, but there is also strange stuff which questions it...
* the BIOS update which ruined working configuration (Lenovo T500 + CCFL over VGA) had a change in dithering technique - strange is that actually the update should have turned off the bad temporal dithering
* after the BIOS update, setting the color depth to 16 bits made the T500 built in screen usable again (less colors, less color dithering?) - strange is that before the BIOS update setting to 16bit had no effect, and 16bit solution still has no effect over VGA or DVI
* people here on forum reported that switching to monochrome (like using high contrast schemes for people with dissabilites) brought some relief, also it seems that slow reaction screens are better than fast ones (color switch is not so harsh and is easier on the eyes)
* according http://en.wikipedia.org/wiki/List_of_iOS_devices iPhone3GS,iPhone4, iPad 1 & 2 have either 8 bits per color or 6 bits with no or only spatial dithering, and it seems these devices are causing no or little problem - strange is that I personally have issues with the iPad2, however it is way better than the iPad3/4, but not perfect like the iPhone4 or iPad1
* using a macmini + thunderbolt display in apple store seemed very comfortable (compared to Air, Retina, iMac)
- try 16bit color depth, it may work, unfortunately not possible anymore in MacOSX and also in Win8 (for Mac there are some utilities which have the color depth option, however only 32bit choice is offered, at least when no external screen is connected)
- try a display with no PWM and 8bit per color (Cinema/Thunderbolt, Dell U2413, U2713H, maybe more out there but these are the only ones I know)
I personally wait for the availability of the U2413 (it even doesn't have white LEDs but some new LG invention, green and blue LEDs) and will let you know more once I test it.
The bad thing about the problems discussed in this and other threads is that it has started a long time ago, yet manufacturers have not responded. We must be a really small minority.
It seems based on various comments on the net that there are some good led monitors for the eyes without PWM (eg EIZO 2436).
But is it possible to manufacture a portable device like a smartphone or a table or a laptop without using PWM for dimming? Is PWM the only way due to energy issues? I mean people on the move obviously cannot carry a display. I wonder if i could ask a built-to-order laptop/tablet from a local store and ask them to use analog backlight. I think that in the EU where i live the manufacturing of ccfl displays is prohibited, so as i see it either i buy a second hand laptop or ask to make one for me that does not bother me.
Thank you Stefan!
I mentioned months ago that temporal dithering might be the problem, but was completely ignored. I know about the OS X dithering bug, but sadly I didn't research it as well as you have.
I have to correct you on something though. U2413 and U2713H are 10bit monitors which are 8bit + FRC, so they do use temporal dithering. U2713HM is 8bit native monitor without any dithering. So is HP ZR2740W.
Thanks for your reply and clear explanation. I don't have the technical background to really figure out the root cause of this problem but rather I try, try, try and push all the buttons until I hit the right key. I am basicaly eliminating variables and I was very close to conclude that Windows7 is to be blamed. A hardware that works perfectly well with Windows XP suddenly begings to have this issues when upgrading to W7. I wonder if it is software related also for Mac products. Would a MBP from let's say 2008 (which is spared from these problems) being upgraded to Lion get the problem too?
Your dithering theory sounds very plausible and helpful. I'll try to change my settings to the minimun number of colors possible and even change to B&W and see what happens. At this point in time I don't care any more if my screen has to be set at a poor resolution, huge fonts, black and white or whatwever. I just want to be able to work!
I reckon that all together our problems are a combination of variables. Why is this happening also on LED televisions? I can tell that I also did experiment with a Panasonic Plasma TV set and had disconfort in my eyes too. I thought that the more Hz they pump into the technology, the more artifacts are added in between the standard 50Hz refresh rate and that causes issues. My next target on this will be a rather cheap LED Television without frame interpolation, motion flow, perfect motion rate, or things of the kind.
Apologies to everyone to have deviated the conversation to some non-apple products but I think our main interest in this forum is to figure out what's going on with this technologies that are driving us crazy, no matter what the brand is. Thanks very much for everybody's contribution to the forum, we'll find a way out! At last, let me grumble about apple (and other manufacturers). We haven't seen a single word from them to take care of this minority that we seem to be.
@Apple: You might have noticed that we are among the best fans of you. We love your products and we keep on trying workarounds to keep using you. Don't let us down and try to find a solution!
It seems my dithering theory is just a theory :(.
I could verify under Linux that graphic card dithering is off for my nvidia card, however I still get eye strain when using the DVI output and just can't find a relevant difference between VGA and DVI configurations...
It seems also that my monitor performs a dithering on its own no matter what ("snowing" is perceptible on both VGA and DVI) but this seems not to be a problem - since screen is perfectly fine with VGA cable.
Visually, when using DVI the colors seems more vivid, I have no idea why...
Clueless again :(((
Hi Guys and Girls,
What a great thread. I have a condition with my eyes called uveitis and everytime I use a LED display I cant see for a week and could go blind. It is an autommune condition and I think my body attacks my retina as a result from the impact of the LED straining my retina. SCARY I know. I think I am an extreme case with the LED eye strain thing and am pretty depserate,
I am currently using an external monitor on my Imac (with no problems) and dont use any tablets whatsoever, I used to have an iPhone 3gs and iPhone 4 and with prolonged use my eyes would flare out. My LED tv at home also will render me visually imparied for weeks if I use it.
From what I gather most people reckon it is the PWM and blue light that are the issues. I have a samsung display at home (presumably CCFL backlit LCD) and I am totally fine with it. Are there any smartphones and tablets out there that utilise CCFL that you could advise.
Also when it comes to improving my CCFL screens - what settings can i change with regards to refresh rate and colour etc can I change?
Your advice would be greatly appreciated.
I have a new Imac 21.5 inch purchased about 10 days ago, which replaced a Windows based laptop. I am having the same eye issues discussed in this forum. I am getting ready to return it within the 14 day return policy from the store I purchased it. I installed F.lux a few days ago and while it is helping some, I do not feel it has totally eliminated the issue and that it is too risky to go beyond the 14 day return period.
My husband has a MacBook Pro and I have used it some while I was searching for a computer and my problems are not as bad with the MacBook Pro as they are with the Imac. I think that, for me, the Imac screen being much larger just compounds the issue. I can use the MacBook Pro for a couple of hours, and while I may have eye strain, it is not as painful as with the Imac. So, I think the size of the screen increases the problem.
Also, the Imac stand is not adjustable in height and it is a little too high. So, unless you are a tall person or have a tall office chair or a low desk, you are not in a proper ergonomic position. I understand that you should be looking slightly down to the monitor and the Imac not being adjustable in height compounds the issue, as your neck and shoulders are not in a comfortable position.
Now that I am returning my new Imac, I will be going to the local Microcenter store (microcenter.com) where I purchased my Imac to look for a new monitor and pc or laptop. I have read nearly all the messages on this forum and all the technical information provided. While I do not fully understand all of the technical settings discussed, I conclude that my starting point should be looking for a monitor that has the CCFL backlighting. I have seen a few models mentioned within the earlier posts.
If someone can help me know what to look for besides the CCFL, I would appreciate it. Also, I am not necessarily looking for a large monitor, as sometimes the larger ones (even the 21.5 inch Imac), I don't find comfortable for the eyes to "settle on". They are more comfortable at a further distance, but if the resolution makes the fonts too small, I have to move a little closer and then the screen feels too big and your eyes have to scan left and right too much. Some of the monitors previously suggested in this thread were 24 inch and 27 inch, which I feel may be too big for me.
On the Microcenter website, you can narrow your search to monitors that have the CCFL backlighting (and they list 24 models). I am not sure, though, what other specs are important in shopping. Here is a list of some of the other features for narrowing down the choices. Anything on this list below important? If so, which items and what specs should I look for? I have seen other posts referencing the cd/m2 #'s etc. and that is mentioned on this Search list (but I am not sure if it is referring to the brightest setting or not).
Dynamic Contrast Ratio
Native Contrast Ratio
- 0.233mm (1)
- 0.248mm (1)
- 0.251mm (1)
- 0.258mm (1)
- 0.264mm (5)
- 0.265mm (3)
- 0.272mm (1)
- 0.276mm (1)
- 0.283mm (3)
- 0.3114mm (1)
- + MORE
- 1024 x 768 (1)
- 1280 x 1024 (7)
- 1440 x 900 (5)
- 1680 x 1050 (1)
- 1920 x 1080 (8)
- 2560 x 1440 (1)
- 2560 x 1600 (1)
VESA Mount Compatibility
I don't think you should attempt to choose based on specs. You mentioned height adjustability in your earlier post, so that feature may be something you want to filter on. Otherwise, you should really read some reviews at some of the sites that review monitors. That will give you information on the quality of the products, which will get you a lot further than the specs. Just to suggest a few, check out http://www.tftcentral.co.uk/, http://www.prad.de/en/index.html, http://www.flatpanelshd.com/ and http://reviews.cnet.com/monitors/.
Like you, I don't need 24+ inch monitors. I own a 2009 vintage Dell 2209WA which is superb. It still had CCFL backlighting. Sadly it's been replaced by a model with LED backlighting (U2212HM). The new model may be OK, maybe others can comment.
My other monitor is a 23 inch Asus VH236H which is a decent lower end model that has CCFL backlighting. The only negative I have on it is a high pitched hum that you can hear in a quiet room. That might or might not annoy. Also, the stand is not height adjustable.
Good luck, I hope you're able to find a monitor that works for you.
Well, refresh rate was a big issue with the old CRT monitors. LCD monitors are not refreshed the same way, so it's not an issue per se. However, LCD monitors to have a response time specification which becomes an issue if you are playing video games or watching videos. If you are not going to be using the monitor extensively for either, then you can ignore response time. If you will be, pay attention to monitors that are recommended for gaming, they will have a response time that low enough to prevent what's called "ghosting" where you have a remnant of the last frame on the screen with the new frame.
Thanks. I won't be doing gaming, just mainly using it for reading, writing, email, web research, etc. Just trying to make sure the next monitor I get won't hurt my eyes, as it's a bit of a hassle returning things. And,I already have to clear my email, etc. off this Imac I've had for 12 days and pack it back up.
I will try and spend some time on the monitors in the store, but it's hard to sit or stand there too long on each one. So, my strategy is to see which monitors they have in the local Microcenter store that have the CCFL backlighting, then read up on reviews on those models, then go try them out. Bringing one home will still be experimental, though. And, I will need to shop for a laptop or pc to replace the Imac as well.
Some of the 24 models they have listed on their website with CCFL are "refurbished" (unfortunately many of the smaller ones that I would prefer) and I am thinking I should stay away from those, since various parts may have been changed out on them. I am thinking that so many monitors are large and wide now, as the manufacturers probably know they are more impressive looking in the store when people are shopping. I don't want to have to "pan and scan" left to right while using one, though.
After using the F.lux software for a few days, I think it has reduced my eye strain, at least 50% or so or maybe more; but, I still think it is too risky for me to keep the Imac past the 14 day return period.
Just finished reading through this thread after searching for information on a non-apple related issue, thanks very much. I figured that what I post may be of some small use in helping someone source the cause of the issue. Due to this issue, I recently had an eye test, my distance eye sight is 6/5 in both eyes, that's what 20/16 in old numbers? My near vision is also perfect so I know it's not a requirement for glasses. Short of a 'floater' my eye sight is otherwise 'perfect'.
I had originally presumed that everyone viewed things the same as myself and that the 'problem' I see was just a by product of modern 'LED's, but having spoken to a few of my friends they looked at me like I was bonkers.
The issue seems limited to 'super bright LEDs' and I must stress that it's not all LED's that cause the issue. Car rear brake LED lights, traffic lights, TV's and some mobile phones seem worst.
The effect is like a motion blur, hard to focus, flashy disorientating effect that I struggle to put into words.
The issue is compounded when the LEDs move in relation to my eye and severe enough for force me to look away. I would also say that it's worse with white writing on a black screen. I think the effect is worse when the LED's are facing me.
I work in IT and get to play with a lot of mobile tech.
- I am fine with most LCD mobile phones,
- My HTC OneX doesn't cause an issue, (yet the home back buttons which are back light automatically during low light certainly do), most iPhones I have played, tested and setup seem fine also.
- The worst seems to be new flagship Samsung screens, the S3 and the Note2 are very uncomfortable to look at, even to the point whereby someone else is using them and the screen in in my field of view it 'bugs' my eyes out.
- I was an early adopter of the HTC Desire and mine was the original AMOLED model which had no issues. So it's not all AMOLED screens.
I hope that helps.