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Comment by aurelianito | Hacker News Reader

It is also anecdotal, but I feel exactly the same. CRTs are far more fatiguing flat monitors for me.

It could be because of the refresh late. Officially, people can't tell the difference past 60hz, but I've always found anything less than 75hz gives me migraines.

[[At least, the only times I've had a migraine in the last three or four years were when I was setting up a new system and forgot to frob the monitor to 75hz (I don't understand why it doesn't just automatically detect this stuff. But there we go...)]]

If you're trying to confirm that flat panels are better (anecdotally) than CRTs, I'm not 100% sure I follow your logic here, because:

- Most CRTs, generally, could operate at 75Hz on the low end and upwards towards/beyond 120Hz on the high end if set in the system settings

- Most flat panels default, and may be capped, to 60Hz (unfortunately including the one I'm on now) and only in recent history do they have relatively expensive options boasting 120Hz

Flat panels do not flicker [1]. Regardless of the refresh rate their pixels stay constantly illuminated.

[1] At least not in the sense of CRTs. Most do perform temporal dithering of colors by alternating between nearby shades.

And GTX9xx/10xx GPU's, most AMD GPU's and Macbook Pro external display outputs use temporal dithering, regardless if the display is native 8-bit or not.

I'm working on a .kext to fix the latter, but it's hard work and we still have a long ways to go.

From an eye strain point of view, the big distinction between an LCD and a CRT at the same refresh rate is that the LCD’s backlight is on continuously; a CRT flickers at its refresh rate. 60 Hz flicker is easily visible, and, at least for me, isn’t particularly comfortable to look at (I used to crank the refresh rate up on my monitors for this reason).

LCD monitors with PWM-dimmed backlights can have the same problem, but they usually run at higher frequency. I still run non-PWM monitors for my daily work, though.

Flat panels differ in one very important aspect though. A CRT monitor achieves its refresh rate by briefly illuminating phosphors on the surface of the monitor, and relying on human persistence of vision to achieve an image. The CRT monitor is only actually illuminating a single pixel at a time, and simply scans the surface very rapidly. So, increasing the refresh rate on a CRT monitor has a very visible impact on the smoothness of the image and the visibility of any flicker.

Flat panel monitors may only have a 60 Hz refresh rate on average, but each lit pixel is illuminated 100% of the time. The refresh rate dictates how long each pixel takes to change to a different color and affects the smoothness of motion and video, but a static image on a flat panel display should have no flicker at all.

(Assume for a moment that the flat panel's backlight has no inherent flicker; some flourescent backlighting suffers from this, but it's unrelated to the display's refresh rate. I'm also glossing over some of the finer technical details in both kinds of tech.)

> relying on human persistence of vision

FYI: persistence of vision was debunked back in 1912[1], 1976[2], and again in 1993[3]. It's still taught in film classes, and they justify this by claiming that it's "disputed". It's not disputed, it's downright incorrect. Please stop referring to it, as this only confounds the idea, and helps it with false validity.

[1]: https://www.researchgate.net/publication/34413805_Experiment...

[2]: https://www.researchgate.net/publication/268400050_The_Myth_...

[3]: https://www.jstor.org/stable/20687993?seq=1#page_scan_tab_co...

Recent HN thread on display flickering: https://news.ycombinator.com/item?id=16087871

Reply on news.ycombinator.com