I recently tried a sony vaio which filmed in the shop with the high speed camera had no visible flicker. However when reached home and unpacked the sealed deviced it proved to flicker with around 200Hz.
Gone back to the shop and exchanged the device with the one in the window. Sadly after using it for about 1 hour the same feeling installed as when using the macbook air :(.
So tried to verify the theory of MauiTechnoGeek2 that the leds are never turned off all the same time (in case of the second vaio device). Indeed when directing the phototransistor towards edges of the screen, a slight oscillation became visible.
However when trying to measure at the edges the ipad 2 which is also causing me issues, I couldn't see something concludent. Maybe I need to put some kind of tube around the phototransistor so that I can increase the precision of the measured area...
This thread has been a gold mine of information ab out a problem that recently hit me.
First I have to say that I am almost blind. I 'm mainly blinded by light and need to be at about 5cm of a screen to read it well. Hence why I often invert colors or use browser extensions to make webpage colors easier on my eyes.
I had a MBP from late 2006 and had no problems with it. Same goes with my iMac from 2007.
I recently wanted to change my MBP and got myself a Retina one. I suffered from eyestrain easily after using it for 15 minutes or so. I at first thought it was because of the high-density display but after I exchanged it with a matte non-retina MBP, I realized it wasn't that. Reading this thread made me believe it was probably caused by the LED backlight and that there is noe asy solution, so I'll at least give you info on what I've tried so far, and what works for me or doesn't.
Among the devices I own and which are working for me : iPad 2, iPhone 4S, MBP from 2006, iMac from 2007, PC with a HP display( can't remember the ref right now.)
What I tried to make it better : I tried changing the brightness setting, inverted colors, but it didn't work well. I tried to wear my sunglasses (special sunglasses with darker glasses so I can see better outside.) but this just made the effect a little less painful, but still present.
I did notice however that when using Windows under Boot Camp, the display was better to look at somehow, but the pain came back after 30 min-1 hour or so. It still feels better than OSX for some reason.
I'm going to try the color profile modification someone mentionned before, and see how it works for me.
As a person with disabilities, I'd just like to point out that Apple is committed to working for the most accessibility that can be had from its products. If you're having problems, please see http://www.apple.com/accessibility/ and the email address located there. Suggestions can be had for dealing with any type of accessibility issue.
From Amerix to AxelTerizaki,
Wellcome to the nearly blind group!
This problem is really a nightmare when you have to work, read or write.
While waiting manufacturers produce a healthy problem free screen, and before getting blind, have retina damages, or macular degeneration, you can try the following:
Limit working time to 15 minutes, keep your eyes 2 feet away from the screen, increase all reading and writing formats, always have good lighting around. It helps!
Eric Leung1 wrote:
"However, I have serious issues when trying to look at the MacBook Air for an extented period, and yet it has constant light too?? If I did not do any wrong with my tests, this result may rule out the entire assumption of this thread that it's PWM that's causing the eye strain!
Now I'm very confused!! "
Eric, have you tried completely reducing the blue color in the RGB settings and setting red to maximum with the MacBook Air that has constant light? This way you could at least rule out the spectrum as the problem. The problem for you may be some additional factor, not just flicker alone. Who knows, maybe reducing blue is all you need to do for comfort. Please try it and write back.
Hi Dovez, with all the tests I have tried and others have been trying in this thread, I'm now beginning to believe that the problem is probably not due to PWM. We don't seem to be able to find trace of PWM in recent Apple displays, either the displays are flashing at a super high frequency (e.g. 20khz) or Apple is using a different method in dimming the displays.
I have tried using SuperCal to "calibrate" my screen to a green monochrome, a red monochrome as well as a blue monochrom.
I found that the green monochrome does seem to be a little bit easier to the eyes compared with the other two colors. An inverted green monochrome (green text on black background) seems even better.
The result was probably not definitive though, my eyes still get tired after some time. But that's might be due to looking at a bright green screen for too long or maybe my eyes got too tired after trying many different combinations.
Very unfortunately, blue light is nicer for screens.
Blue light can be toxic, experiments on animals show it, and some sensitive eyes, especialy when aging, could be badly affected.
Intensive blue light as produced by led is more toxic.
And when combined with the square led signal, it is like recieving blue needels in your eyes! Many per second!
Amerix, still searching for a solution!
Don't want to complicate the situation, but perhaps you should check this site's inversion test pictures, starting with Pixel dot-inversion and ending with Line-paired dot-inversion (green test):
Perhaps the test pictures show a stronger flicker on the LCDs without PWM that you are sensitive to (like the MacBook Air) than the NEC with PWM that you can tolerate. And perhaps you are sensitive to the 30 - 40 Hz flicker of the LCD screen itself.
Hi Dovez, I don't have the MacBook Air with me at the moment, but I have tried similar dot-inversion tests from other websites before. What I think is that the flicker detected through these tests would exist in almost every LCD displays. I have tried that in quite a number of different LCDs, and found that even those expensive EIZO displays has that flickering behavior when displaying a particular pattern. The difference is just the flicker would appear in different type of pattern due to different designs of the displays.
These kind of flickering should be visible only when displaying some particular form of pattern, and shouldn't affect most of scenarios where we use the displays.
I believe this is un-related to the eye strain issue we are experiencing.
Eric, I have an expriment you could do. To narrow down if it's the screen or the backlight causing your eye strain you could turn your problematic LCD towards a wall at night and see if you get symptoms from staring at the light reflected from the wall. If you get problems with looking at the light, then some aspect of light is the problem, not an aspect of the LCD screen.
That's an interesting idea, I can have a try some time later.
Actually, I'm pretty sure it's the LED light causing the problem, just that I can't tell how exactly the LEDs are making myself uncomfortable.
I'm fairly sure that if I'm inside a room with LED as primary lightings, I could sense the tense in my eyes. There have been a couple of times when I'm reading inside salons or cafes, my eyes became somewhat uncomfortable (not badly uncomfortable, but I could feel my eyes tensed), then I look up the ceiling and see LED lights shining above me.