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Tokei · 04-27-2019, 08:50 AM

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.

04-27-2019, 08:50 AM	#44
Tokei Member Posts: 19 Karma: 2075226 Join Date: Apr 2019 Device: Kobo Forma	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.