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Reload this Page Kobo forma screen flickering/pwm issues

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View Poll Results: Does the kobo forma light flicker cause you eye strain?
yes 9 14.06%
no 55 85.94%
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Old 01-09-2020, 02:05 PM   #61
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Originally Posted by koboyedi View Post
The flickering is also visible to the camera when not filmed in slow-motion. While it's not visible while reading, your brain still processes these. Here's a short clip showing the issue:

https://vimeo.com/383801739
But the camera was able to catch CRT screens flickering when we cannot see such. I'm not sure that's a good test.
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Old 01-09-2020, 02:32 PM   #62
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But the camera was able to catch CRT screens flickering when we cannot see such.
That's not a CRT screen, that's an LED ceiling lamp lighting the scene.
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Old 01-09-2020, 03:39 PM   #63
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Quote:
Originally Posted by koboyedi View Post
The flickering is also visible to the camera when not filmed in slow-motion. While it's not visible while reading, your brain still processes these. Here's a short clip showing the issue:

https://vimeo.com/383801739
You'll notice in that video the bands of light are clearly horizontal, whereas the kobo lights are mounted along the the side... Whatever was causing the flicker in the video, it *wasn't* the kobo.

Edit: Err, probably my misunderstanding on how the PWM flicker shows up on camera.. I guess it depends on which way the camera is scanning the image, rather than actually captruring at the speed of light
Last edited by rashkae; 01-09-2020 at 03:54 PM.
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Old 01-09-2020, 04:09 PM   #64
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Yes, but regardless, I now decided to cancel my replacement shipping and get a refund for the Forma instead.

I have watched comparisons with the Kobo Libra in the meantime and the Libra uses infrared light instead of pulse LED (or whatever it's called) so there is no flickering going on at all. There are also no light spills or dark stripes/corners etc. Next to this the screen sits directly on the panel (no air gap) which makes everything look sharper.

So the advantage of the Libre over the Forma:
- no light spilling on edges
- absolute evenly lit display
- no flickering that stresses the eyes
- sharper display

Yes, I'm loosing some screen estate, but imo the benefits do outweigh this. Also, I have like $100 left to spend on ebooks.
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Old 01-09-2020, 06:57 PM   #65
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another helpful video

https://youtu.be/uo3jvw5jpmQ?t=884

(Starts at 14:44)
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Old 01-09-2020, 07:24 PM   #66
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Quote:
Originally Posted by koboyedi View Post
I have watched comparisons with the Kobo Libra in the meantime and the Libra uses infrared light instead of pulse LED (or whatever it's called) so there is no flickering going on at all.
Quote:
Originally Posted by koboyedi View Post
another helpful video

https://youtu.be/uo3jvw5jpmQ?t=884

(Starts at 14:44)


I was going to ask what you meant by "the Libra uses infrared light". Then I watched the video. Her reference to IR is for the touch. It has nothing to do with the lighting. And she got it wrong. The Libra H2O uses a capacitive touch.

She is right in that the Libra H2O does not use PWM to control the light level. But, it's just a coincidence that she was right.

And I left the video on in the background while I wrote this. But, I had turn if off because it is terrible. The "highlight" was a terrible explanation of the progress bar and a suggestion to look for hacks to turn the header and footer display off. I've no idea why she thought suggesting that was better than using the options.
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Old 01-09-2020, 07:24 PM   #67
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Quote:
Originally Posted by koboyedi View Post
another helpful video

https://youtu.be/uo3jvw5jpmQ?t=884

(Starts at 14:44)
Except that just about everything she says is wrong. I mean, great, that you and her like the Libra... (wonderful device, I think they did fix lots of misteps with the Forma).. But Libra does not use Ifra-Red.. nor does infra red have anything to do with PWM light (or lack thereof). I certainly can't see any different in sharpness between the Forma and Libra. The last and probably only 300DPI reader with IR screen was the Kobo Glo HD, which indeed probably had the sharpest image of them all, (but the light was also really harsh on that reader, being before Comfortlight was introduced.. that made a big difference.)
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Old 01-09-2020, 07:37 PM   #68
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Quote:
Originally Posted by rashkae View Post
Except that just about everything she says is wrong. I mean, great, that you and her like the Libra... (wonderful device, I think they did fix lots of misteps with the Forma).. But Libra does not use Ifra-Red.. nor does infra red have anything to do with PWM light (or lack thereof). I certainly can't see any different in sharpness between the Forma and Libra. The last and probably only 300DPI reader with IR screen was the Kobo Glo HD, which indeed probably had the sharpest image of them all, (but the light was also really harsh on that reader, being before Comfortlight was introduced.. that made a big difference.)
The pedant in me says:

The Glo HD does have "Comfortlight". The colour changing version is called "Comfortlight PRO".
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Old 01-09-2020, 07:41 PM   #69
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Originally Posted by davidfor View Post
Her reference to IR is for the touch. It has nothing to do with the lighting. And she got it wrong. The Libra H2O uses a capacitive touch.

She is right in that the Libra H2O does not use PWM to control the light level. But, it's just a coincidence that she was right.
thanks for setting this straight

Quote:
Originally Posted by rashkae View Post
I think they did fix lots of misteps with the Forma
may I ask what those are? I think of the soft-rubber wedge handle of the Forma which just loves collecting fat from my fingers

Quote:
Originally Posted by rashkae View Post
Except that just about everything she says is wrong. I certainly can't see any different in sharpness between the Forma and Libra
oh thanks for that. I thought the screen (recessed vs flush) would make a difference in sharpness or reading comfort. I only have the Clara HD for reference and to me it appears that reading on the Clara is more comfy than on the Forma. But then this might be just a psychological thing when you're convinced it is that way.
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Old 01-09-2020, 07:59 PM   #70
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Old 01-09-2020, 09:36 PM   #71
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Quote:
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thanks for setting this straight


may I ask what those are? I think of the soft-rubber wedge handle of the Forma which just loves collecting fat from my fingers
I rather prefer the softouch, or more accurately, I dislike the cheap feeling hard plastic of the Libra.. but that's strictly a matter of preference.

The mis-steps I spoke of are plainly obvious, the light band, and the PWM. I firmly believe that the PWM issue is much ado about nothing, (ie, all in people's head.),, but regardless of whether I'm right or wrong, I think it turned out poorly for Kobo's flagship reader.

All that being said, the Forma very quickly became my favorite reader of all very shortly after I had it in my hands.
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Old 01-09-2020, 10:04 PM   #72
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this is why I got the Libra. Many people complain of flickering on the Forma
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Old 01-09-2020, 10:19 PM   #73
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this is why I got the Libra. Many people complain of flickering on the Forma
Please point them out. Most people say, "It has PWM, therefore it is bad". I do not believe I have seen anyone state they could see the flickering under conditions that were even remotely close to what someone would read under. The only evidence I have seen of the flicker is some videos that were done in a way to show the flicker.
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Old 01-09-2020, 10:27 PM   #74
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Many people complain of flickering on the Forma
How many of these "many people" have seen an actual Forma and not just the contrived videos?

And how many actual owners agree with what rashkae said about the so-called PWM "issue"?
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Originally Posted by rashkae View Post
... I firmly believe that the PWM issue is much ado about nothing, (ie, all in people's head.) ...
FWIW, I agree with this one, too.
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All that being said, the Forma very quickly became my favorite reader of all very shortly after I had it in my hands.
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Old 01-09-2020, 11:26 PM   #75
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Libra uses infrared light instead of pulse LED (or whatever it's called) so there is no flickering going on at all.
Out of curiosity, do you think you will find reading while wearing infra-red night vision goggles to be rather uncomfortable?
Last edited by DNSB; 01-09-2020 at 11:34 PM.
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