andc i suspect that notebookcheck pwm reviews are highly untrustworthy.

i have read several reviews that dont match.

Also my Xperia XZ 2, in notebookcheck, says it has pwm until 28%. But i check that it has also beyond that point almost until 100% with my canon 550D at 1/4000. I also use a 1.4 aperture lens, so i can i have light to check it.
Above the 28% brightness what happens is that the phone seems to go to a higher pwm frequency.

Until 28% is 2khz, above that seems to double it.

I am waiting for my oscilloscope to arrive to check it properly.

So maybe some displays, change PWM frequency depending on brightness.

  • AGI replied to this.
  • AGI likes this.

      It would be good to know if all the Notebookcheck's reviewers use the same gear and procedures to test for PWM and what the max frequency that can be checked is. I've also seen different results on almost the same machines, but I thought that this is related to different panels or internal components. Actually such information should be provided by manufacturers, the same way as refresh rate, contrast, since it becomes a rather important factor and isn't so easy to test properly.

        andc You record on your microscope with HTC 10 at 120 fps?

        The leds change at different frequencies. For instance if you could record at 2000 khz you could watch them flicker at a different rate, if they would have pwm. For 120fps they change differently, if you record at 60fps also differently.

        Maybe for the eye there is a worst range.

        • andc replied to this.
            a month later

            tfouto
            I know - having a faster camera (ie. > 100kHz) could reveal the actual pattern of flickering, 120 Hz just informs that something is going on, but you can't be sure what the frequency is probably.

                andc i bought the same microscope than you. I just received it.
                How did you manage to record? It's small and i it's difficult to put a camera in the microscope.

                • andc replied to this.
                    15 days later

                    tfouto
                    (Please excuse late reply, I haven't been keeping eye on the forum too often recently)
                    It may be hard to explain, but that's how I do it:

                    • Phone - I created a small construction on top of microscope so phone can be safely placed and aimed against focus of microscope. It's a wood "support" on which phone lays and this wood is glued using two-sided tape to microscope. I've also added two rubber bands to keep the phone in place and it works pretty well. If this information is not enough, I'll make a photo of how it looks 🙂
                    • Bottom - you adjust the shelf of microscope using rotating wheel, so basically screen that is going to be tested needs to be placed on this shelf (it's good to remove the metal holding parts to avoid scratches on surface) and its height needs to be adjusted to make sure that you / camera sees pixel correctly. Since it usually requires to put screen flat on around 7cm I use a thick book as a support on the other side and it's fine - both for phones and laptops / tablets. It's not a sturdy construction, so it's safer to do it on wide table, or floor.

                      tfouto Also my Xperia XZ 2, in notebookcheck, says it has pwm until 28%. But i check that it has also beyond that point almost until 100% with my canon 550D at 1/4000.

                      Have you ever used Iris? It would be nice to check that it effectively allows for any level of brightness without inducing PWM...

                      tfouto Until 28% is 2khz, above that seems to double it.

                      Should not 4kHz be "safe"?

                            AGI I never used Iris.

                            I dont know if there is a safe range. No one knows i think.

                              hpst
                              thats funny. ive owned a samsung 40"b750 lcd tv maybe 6 years ago and the experience is still great. it uses ccfl lights. the last 6 years i tought it has something to do with the pwm. last minth i did some tests with my camera and oh lord it has pwm 🙂
                              ive owned several new tvs (sony lcd, samsung and lg plasma, philips lcd, samsung lcd and some projectors (led and dlp) up to 2000€ from sony for example...) because i wannted a bigger one, but they all produced eyestrain and headache. i am still using my samsung b750 and i hope it will never die.

                              for computer monitors ive found a very good one from benq with mva panel and flicker free technologie. for smarthones its the same. tested several models from sony, lg, samsung.... after 2 years ive found a realy good one from a small company from spain. they called (aquarius x5 plus).

                                  hector Could you please share the model of benq monitor, please? I am heavily investing in lighting, computer tech to be able continue my IT job, while my good old Samsung monitor works.

                                    23 days later

                                    hpst Even if I spend 700usd on this VA panel I still cannot use laptops (never found one with TRUE VA in it...just IPS variants using VA in the name, or mobile devices so it's just a more expensive CCFL situation limiting you to specific and less common stuff.

                                    Yea, if AMVA is a possible solution, it seems that there are no laptops using this type panel.

                                    And on the 32gk850g and it's variants, it seems that these displays are really bright and probably even too bright at the minimum setting. The original poster mentioned above that he is using it in Reader Mode with blue light blocking glasses because of the brightness. That for me sounds like a no go.

                                      a month later

                                      Big thanks to f3likx

                                      I ended up trying a couple of LG VA monitors. Both have been a major improvement. Not perfect eye fatigue relief for me, but much much better. I am thinking about trying out a Samung VA QLED just to see if there is any major difference to what LG offers. The two I have tried from LG are the 32UD60-B (4K) and the 32GK650F (1440). The panel quality is worse on the 4K, but I still prefer it for it's higher PPI for text sharpness. I am running it at 180% scaling and at a viewing distance of about 3 feet, which makes most everything of a very comfortable size.

                                      Also what I have tried along the way is switching back to my IPS monitor, which ends up giving me eye fatigue sooner or later. And I tried out a newer gaming TN monitor, the Dell S2716DGR. It also gave me eye fatigue. To really find out if the IPS and TN were more fatiguing than VA, after eye fatigue began to really set in, I swapped in the VA, and the relief began right away, and within around an hour or so my eyes were back to feeling much better. And it is even better if I use the VA without having first used the IPS or TN monitors. I would say that the overall improvement is major, where instead of getting painful eye fatigue, my eyes eventually reach a tired level and stay there. It feels different than fatigue, where my eyes ache and my focus begins getting blurry. And the general look and feel on the eyes of VA is warm and soft. If I had to put a number on it, I guess I would say that using a VA is a 75% improvement, enough that I can get on with using a computer for text work and everything else without worrying about getting eye ache.

                                      Any way, VA is definitely worth a shot.

                                      a month later

                                      I have an Eizo CG223W which has an S-PVA panel. Works also better for me than IPS and TN.
                                      Will get a Dell 2407wfp on Monday. This is CCFL backlit. Will update on how it goes.

                                        deepflame Will get a Dell 2407wfp on Monday. This is CCFL backlit. Will update on how it goes.

                                        Good luck - I have two of them and with a "good" video card I find them great to use on a daily basis.

                                            reaganry ok, thanks for the pointer. Have the opportunity to get one for 15 EUR. Guess I cannot do so much wrong here... 🙂

                                              a year later

                                              Please see this:

                                              Do you find it difficult or easy to focus on text on VA panels? Did you just get used to it? Did you get headaches and did they eventually pass?

                                              On the TN panel (BenQ XL2720Z) I find text is easy to read. It's crisp. It's perfect. I can focus on it without issue. I don't even notice it because it's just easy. The background colour is flat.

                                              On the VA panel (LG 32GK850G-B) it's just... not. It's like the edges of the letters are soft. I understand that the pixel structure is different but it's so difficult to put my finger on it. I honestly feel like my eyes strain more to read, and after a few months I'm feeling like my eyes are worse in general. Which has got to be bollocks.

                                              It could just be because things are slightly differently sized, but then I increase the text size and there's still this thing that's hard to quantify. Like it's just slightly out of focus. And anything a few inches from what you're directly in front of, the background color seems to shift. It's a shimmer like on those old kids toy pictures that would look like one thing and then another if you changed your viewing angle.

                                              I know TN panels are supposed to shift a lot but when you're sitting in front of them, they don't – at least not in the same way. Maybe it's the screen coating?

                                              When gaming, it doesn't really matter; there's not a lot of text to be looked at. But when working on notepad, especially on a dark background... it's.... really distracting.

                                              Has anyone else experienced this? Do you just get used to it in the end? Are there any solutions? I've tried using Windows upscaling for text but it blurs things something awful.

                                              Edit: It could just be the anti-glare coating. I don't know. The BenQ doesn't have it.

                                              Examples of what I'm referring to:

                                              Link to the thread: https://forums.whirlpool.net.au/archive/2766887

                                              On the matter of refresh rate, I can't find my last post where I asked about 75Hz being of benefit for desktop usage. One says:

                                              Refresh rates do make a difference. I can't do 30hz 4k. Kills my eyes so I had to get a new card to do 60hz on all three 4k monitors. I haven't tried the 120hz monitors yet.

                                              I'm guessing above 60Hz on the desktop is mainly of help for videos and conferencing. It shouldn't help eye strain for most content, unless I'm missing something.

                                              15 days later

                                              Interesting comment:

                                              Both IPS and TN panels hurt my eyes, but only newer ones.

                                              I've heard here that older IPS are worse than newer ones because of thicker anti-glare finishes, and old TN panels are really bad compared to newer ones, yet he says they're more comfortable for him.

                                              7 days later

                                              Does anyone know a VA monitor with a low backlight brightness?

                                                dev