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 p.1 #13 · Any users suffer symptoms linked to PWM with Z8 or Z9 EVF's | |
Taperwing wrote:
FWIW, PWM (pulse width modulation) is used all over the modern digital world. It is simply an easy and efficient way to vary the intensity of a value, such as voltage, which correlates to brightness, by simply turning the signal ON (100%) for a certain unit of time, and OFF (0%), for another unit of time. This is childs play for microprocessors.
For example, say your screen is updated at 120Hz. The inverse of that gives you the period of the waveform, which is about 8.3msec. Say the pixels can only have have two states, ON at 100%, or OFF at 0%. If I turn that pixel ON for 4.15msec and OFF for 4.15msec, the brain will perceive that as 50% brightness. More time ON than OFF gets you brighter, and inverse that for dimmer. If done fast enough, the brain only perceives the average. If done too slow, you might notice flickering, and some point in between, you may not directly perceive the flickering, but something in your subconcious does, which may induce a headache. Direct illumination LEDs can turn cleanly ON and OFF in nanoseconds. Certain LEDs also excite applied phosphors, to change color or quality of light, and those are a bit slower, as the phosphor continues to glow for a bit after the excitation has been removed.
In office settings lit with fluorescents, some perceive a slight flickering. There is a very brief dimming of output when the AC waveform crosses 0V, from either direction. However, the phosphors on the inside of the tube, which are excited to produce ligtht, never full go dark. The time constant on an incandescent filament, which is just a tungsten filiment heated in a vacuum to the point of glowing, is much longer, and even if driven by a square wave, PWN signal, the frequency would have to be quite slow to be noticed by human eyes....Show more →
Appreciate the more technical insight, it is useful to see that explained - certainly I have had issues with Philips Hue colour bulbs in the past caused by PWM. Mainly the real side effects/symptoms seem to come from OLED displays used either on mobile phones, more so now tablets and in some cases laptops.
Many report they are unable to use any of these devices now that LED/IPS displays have been dropped. The original Oneplus 3 OLED phone I noticed the issue with was back in 2016. Apple have been well aware of this for 8-9 years now, it took them all that time to release the iPhone17 Pro which has an option for PWM sensitive users, that option turned out to be really of no use in the real world.
At the moment for the Nikon cameras, certainly the Z8 and Z9 with regards the EVF, it is looking more promising. Nobody has really come back reporting any major issues, on a technical level it seems the hardware used should not trigger symptoms. Once I get hands on for a few days I will be able to give some feedback, since I am very sensitive to OLED PWM, the outcome from testing should be a good gauge for the minority who it affects.
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