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View Poll Results: Does the kobo forma light flicker cause you eye strain?
yes 9 14.52%
no 53 85.48%
Voters: 62. You may not vote on this poll

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Old 11-16-2018, 08:41 AM   #31
m_j
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My cellphone can catch the flickering, but I cannot perceive it with my eyes. I haven't had any physical issue with the flickering, I think I am not sensitive to it.
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Old 11-16-2018, 09:50 AM   #32
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Originally Posted by m_j View Post
My cellphone can catch the flickering, but I cannot perceive it with my eyes. I haven't had any physical issue with the flickering, I think I am not sensitive to it.
i would say this is the least of the Kobo Forma's problems/issues.

best wishes koboy
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Old 11-16-2018, 10:21 AM   #33
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All Samsung cell phones use pwm - are you all using Apple instead? Oh, and the iPhones X, XS and XS Max also have pwm
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Old 11-16-2018, 08:44 PM   #34
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Originally Posted by rma View Post
All Samsung cell phones use pwm - are you all using Apple instead? Oh, and the iPhones X, XS and XS Max also have pwm
I suspect it’s one of those it’s only a problem in your head kind of things for a large group. They were told this causes eye strain so now it’s the cause of any and all eye strain when electronics with screens are used.

I’m sure it affects some small group of people and they have my sympathy but this is hardly a problem. One can simply look at the poll results to see the evidence to back up my theory
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Old 01-31-2019, 08:50 AM   #35
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Hello everyone,

This is my first post here. So far I was satisfied user of Inkpad 1. This device works as expected, the only reason I was looking for alternative was blue (non-natural) back-light - especially for late reading and rather high weight of 350g.

Kobo Forma looked like a great replacement, both in terms of the weight & design and natural (yellowish) light. So this Monday I have ordered one. Later that day I came across PWM back-light flickering issues (reading this forum) - I was a bit disappointed, as I am in principle against PWM (my reasoning below) and I am carefully checking all devices and LED light bulbs against PWM in my home. This time I was ordering online and it hasn't occurred to me that eReader can have PWM.

So I took the PWM claims with a grain of salt, and decided to give it a try and test it myself. The device arrived to me Tuesday. I opened the box and took my iPhone XR and I was (unfortunately) able to reproduce flickering in slo-mo. Like some of you have noticed, newer iPhones have some sort of PWM adaptation so flickering was visible just for a short while when I move my camera towards Kobo Forma. I took my wife's iPhone SE and there it seems there is no PWM adaptation in slo-mo at all, so the flickering was more obvious and visible all the time - you can find my footage there: https://www.youtube.com/watch?v=o4U-TZt-W8U

The device has been updated to the latest firmware before making the video. Finally, I have decided to return it.

Now I little bit info why I am generally against PWM. While like most of us know, with high enough frequency the brain no longer recognizes screen flickering. As far to what I have read, depending on the viewing angle, individual sensitivity etc. this may be lie somewhere in between 100-200 Hz. So it is very individual. Despite there are no hard proves that PWM has or has no negative (even irreversible) effects on your retina, I believe the peak energies of PWM still reach the retina and depose certain energy.

You may imagine that with some extreme PW modulation scheme that has really long blanks (pauses) and really short pulses of high intensity light, in overall your brain will average it out and perceive it as dim screen. However, the high intensity pulses will still reach and depose the rather high energy on the optic nerve and I can imagine this may cause higher strain of the nerve than continuous low intensity signal energy deposition. In super extreme case you may even "burn" your retina - e.g. with a short laser pulse.

This is nowhere any kind of proof, but simple reasoning. Too bad that Kobo remains silent to PWM allegations or simply denies them - I have seen someone that reported PWM issue to them, but they replied they cannot reproduce it. Well, I could.

To bad also they set the new "standard" where you can really see the PWM, while the others either don't do PWM at all, but rather control the light with voltage (I know it may be less energy efficient), or simply they use super high PWM frequencies (so cannot be seen with 240fps slo-mo).

Finally, I am happy that there are still some flicker (PWM free) devices released, e.g. iPhone XR (while more expensive iPhone X/XS is not) also new iPad. Time will tell what impact all this new "superior" OLED & PWM tech will have on our health, anyways I don't want to test that on myself or my relatives

Cheers,
-- Adam

Last edited by ono; 01-31-2019 at 08:56 AM.
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Old 04-21-2019, 08:52 PM   #36
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I just returned a 2nd Forma this weekend because both had different quality control issues I would hardly deem acceptable with a mid-tiered product, let alone a premium flagship model. The line on the one side was there on both units, and frankly, it didn't bother me. What got me was that the first one had a horrendously uneven lit panel. All LEDs were working. So took it back to Bestbuy for an exchange. The 2nd unit was brand new (it had the Kobo seal on the box) but it was clear to me that it was a refurbished unit! Outrageous. The top right side even had what appeared to be glue of some sort and I could actually insert my fingernail under the screen itself! Not exactly waterproof, nor new, nor very good refurb even thought it was the marked as refurbished. Screw the Forma! Back to the Aura ONE which clearly remains the superior model in 2019.
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Old 04-21-2019, 10:05 PM   #37
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Not exactly waterproof, nor new, nor very good refurb even thought it was the marked as refurbished. Screw the Forma! Back to the Aura ONE which clearly remains the superior model in 2019.
The Aura H2O mark 1 was the only Kobo that required sealing for water proofing. Their other waterproof models use the HZO nanocoating technology.
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Old 04-22-2019, 01:45 PM   #38
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The Aura H2O mark 1 was the only Kobo that required sealing for water proofing. Their other waterproof models use the HZO nanocoating technology.
Hi David - you're right, of course, I should have been a little more careful there but still, they can't seal the screen to the body correctly, how much confidence do I have with an internal coating. It's probably an exception, but just one more drop in the crappy Forma QC bucket.
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Old 04-22-2019, 02:13 PM   #39
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Originally Posted by omnimodis78 View Post
Hi David - you're right, of course, I should have been a little more careful there but still, they can't seal the screen to the body correctly, how much confidence do I have with an internal coating. It's probably an exception, but just one more drop in the crappy Forma QC bucket.
The build quality of my Forma seemed okay for the hour I owned it before my wife "borrowed" it. She does seem very happy with it. "Happy wife, happy life"???
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Old 04-22-2019, 02:15 PM   #40
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I have had my Kobo Forma in my hands since March 1st so I figured I may as well add my thoughts about the screen.

For screen flickering I can get my iPhone to see the flickering in slow mo like others here. But after much use of the Forma the flickering for me is nowhere near slow enough even at the lowest brightness to cause me any problems. Even performing the old trick of waving your hand in the light does not produce a flickering effect for me so the screen flickering is far too fast for my eyes unlike a lot of those LED light bulbs that can be purchased at stores that you can see the flickering by slowly waving your hand in the light.

For screen uniformity at a high brightness there is a brighter side on the side with the buttons but I use mine at 15% and is not noticeable at that brightness. Even my Kindle Oasis has this but not as bad.

If I had two things to complain about something on the build quality I would say I would have rather preferred a matte plastic or metal feel over the rubberized feel. I have bad experiences with rubberized coatings going off and becoming sticky over time but do not know if this one will do it. If not then the coating is fine. The second thing would be the power button not being clicky but I think it was done that way to prevent accidental presses. Mine has no click at all so I do not know when it is pressed until something happens.

As for battery life it destroys my Kindle Oasis. I was charging my Kindle every week with WiFi off. The Forma is at about a 70% charge after two weeks with WiFi left on.
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Old 04-22-2019, 05:31 PM   #41
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I'd worry about the soft touch layer on the *front*, around the buttons, but not the one on the back.

Yes, I may have melted it a bit by using a bit too much isopropyl alcohol when cleaning it ;p.

(well, technically, I dissolved the glue below the soft layer, which means I now have a grippy touch layer because that created folds ;p).
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Old 04-25-2019, 11:24 AM   #42
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As I understand right, the flickering does not happen when the device's brightness is set to 0%. Is that correct?
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Old 04-25-2019, 10:23 PM   #43
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As I understand right, the flickering does not happen when the device's brightness is set to 0%. Is that correct?
When the brightness is set to 0%, the light is turned off.

Of course, no one has actually reported detecting the flickering at any other brightness level without using other tools. Or any ill effects.
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Old 04-27-2019, 09:50 AM   #44
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Dear all,

It’s my first post, so hello everyone.

I bought a Kobo Forma a few days ago in Japan and after seeing the youtube flicker video I became a bit worried. Sure enough, I could confirm the flicker with my mirrorless camera with a shutter speed faster than 1/1000. Interestingly, a slo-mo video with my iphone 6s did not show any flicker. It was also confusing to see a strong flicker at 100% brightness which I didnt expect. I checked that vs. my Thinkpad 470s with FHD screen that according to the site notebookcheck uses PWM at 200Hz. The flicker was much stronger and started at much lower shutter speeds than the Kobo and there was no flicker at 100% brightness. My old Kindle Paperwhite had no flicker at all.

Anyway, such “homemade” testing is quite limited I guess. @davidfor: I saw that you mentioned in a discussion in this forum about the viability of the now older Aura 1 that the Forma had a PWM frequency of 1KHz. Has this been confirmed somehow or did the maker comment?

Other than the PWM paranoia I like the device a lot. I have the bright/dark vertical strip at the button side but I dont mind it at all so far. The power button is a cruel joke and irritates me quite a bit but I will get used to it. On the plus side, I enjoy the big screen, little weight, color temperature and ability to use libraries (but Overdrive software on the Forma is locked in my country even though the libraries use it so I need to go through my Mac with Adobe, what the heck?).

I will try to forget about the PWM and just read a lot (more time for internet research than reading so far), let’s see if I notice any eye strain or headaches.

Thanks everyone for all the prior info, was very interesting.
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Old 04-27-2019, 11:40 AM   #45
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Anyway, such “homemade” testing is quite limited I guess. @davidfor: I saw that you mentioned in a discussion in this forum about the viability of the now older Aura 1 that the Forma had a PWM frequency of 1KHz. Has this been confirmed somehow or did the maker comment?
Someone who took a video calculated the PWM frequency at about 1KHz. But, I have had discussion with someone at Kobo that confirmed that it is 1KHz.
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