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A-L-E-X
Star Engineer
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Light pollution

10 Jun 2019 15:14

I have a UHC filter too but I hate how LED lighting is expanding, it is also affecting cameras and white balance!  Maybe LED lighting will decrease now that new warnings are coming out about it that it damages eyesight!
 
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default0.0player
Space Tourist
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Light pollution

10 Jun 2019 16:24

A-L-E-X wrote:
I have a UHC filter too but I hate how LED lighting is expanding, it is also affecting cameras and white balance!  Maybe LED lighting will decrease now that new warnings are coming out about it that it damages eyesight!

Interestingly, sodium lighting is twice as efficient as LED lighting.
The most eyesight damaging is actually OLED because due to the inherent driving circuit it's impossible to use a steady DC to control the pixels individually.
LEDM88G_Circuit.gif
LEDM88G_Circuit.gif (6.99 KiB) Viewed 352 times

In this picture, it is clear that you cannot light up 2,2 and 3,3 simutainously, you have to drive then alteratively. This is what happened in these OLED screens on some smartphones. To protect eyesight please advocate the use of LCD screens on smartphones.
 
A-L-E-X
Star Engineer
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Light pollution

10 Jun 2019 16:32

Interesting!  Does this mean that OLED TVs and flat panel displays will cause issues?  Worse than old-style CRTs?

What about LED LCD flat panel displays that aren't OLED?
 
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default0.0player
Space Tourist
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Light pollution

11 Jun 2019 01:30

A-L-E-X wrote:
Interesting!  Does this mean that OLED TVs and flat panel displays will cause issues?  Worse than old-style CRTs?

What about LED LCD flat panel displays that aren't OLED?

CRT use electron to hit the fluorescent on the screen, which only light up one pixel at a time, however the fluorescent have afterglow that keeps lighting for a while after electric current is zero. This means it has sort of "motion blur"
OLED use multiple driver circuit to light up the full screen,pixels on each segment of the screen are driven alternatively like the picture on my last post. Means multiple pixels are lit at a time, however the light is zero when electric current flow is zero.That's why if you use a digital camera(or smartphone) to take picture of the OLED screen, the flicker pattern is tilted. The tilt angle is flicker frequency/shutter speed.

Liquid crystal doesn't emit light by itself. LCD have two types, CCFL-backlit and LED-backlit. CCFL-backlit always use PWM dimming because the current range is narrow. But CCFLs, like fluorescent lamps, have afterglow that "dampen" the flicker. LED-backlit can use either PWM or DC(direct-current) dimming. PWM lighting switch the backlight on and off at a fast rate, since the whole screen is lit or dark, the flicker is more damaging to OLED that lit different pixels separately. DC-dimmed LED-backlit LCD doesn't flicker, which is the best.
OLED cannot be driven by DC, no matter how advanced the driver circuit is.

In conclusion. The best to the worst is:
DC-dimmed LED-backlit LCD, CCFL-backlit LCD, OLED, CRT, PWM-dimmed LED-backlit LCD.(based on average brightness fluctuations).
DC-dimmed LED-backlit LCD, CCFL-backlit LCD, PWM-dimmed LED-backlit LCD,  CRT, OLED .(based on individual pixel brightness fluctuations).
picture.png
 
A-L-E-X
Star Engineer
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Posts: 1667
Joined: 06 Mar 2017

Light pollution

11 Jun 2019 14:38

Thanks for the breakdown!  Luckily for me I have the best and second best varieties!

I see that OLED is now being used in new camera EVFs too, that might also cause problems :(

Today we have the results of a new study of 43,000 women funded by the NIH, it shows that artificial lighting at night, whether it's a TV left on while sleeping, a night light, or street lighting, results in an average weight gain of 20 pounds over 6 months!  This is because melatonin also seems to involved in weight control.
 
Terran
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Light pollution

12 Jun 2019 14:03

Perhaps, a compromise could be to pulsate the reflectivity. Have it be an absorber for a portion of time, then if it gets too hot, start reflecting. I cant imagine any cheap engineering method short of using nanotech to pull that off. Perhaps an electrically polarized mirror, I dont know if that would be cheap or not.
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