Interesting article about CFL lightbulbs

logixoul

https://www.visionprooptical.com/471678-is-office-lighting-affecting-your-vision/

Exposure to harsh fluorescent lighting can cause eye strain and blurred vision. The longer you’re exposed to the light, the more likely you’ll experience the problem. Symptoms of eyestrain include sore, burning, watery or dry eyes. Double vision and increased sensitivity to light can also occur.

I researched this further, and it seems the key thing about lightbulbs (for most people - maybe not for us LedStrain folks) is to buy ones that emit "warm" light (aka orangeish) rather than "cool" light (aka bluish). Because the warm ones emit much less UV light.

Soon I'll get an oscilloscope setup (made by a friend of mine who is an engineer) to try and see if lightbulb flicker matters much.

logixoul

Tried an Android app for testing light temperature. It says my overhead (CFL) bulb is 3250 K. I'll try buying the warmest lightbulbs I can find (hopefully 2500 K).

martin

logixoul Warmer light definately helps in my case too.

ensete I have considered intensity to be a problem before. In case of BVD, intensity would mean that because the eyes are improperly positioned, the intense light falls at a different place in the retina, possibly even hitting night-vision rods in the eye. Hence why we consider the light to be too intense, compared to people whos eyes are positioned correctly.

KM

Make sure to get an oscilloscope setup that is able to detect high frequencies in good shape, as CFL's can be driven with hundreds of kHz. An engineer might be able to refine the setup with a transimpedance amplifier circuit. If he succeeds, perhaps he could contribute his knowledge to the oscilloscope thread to help us increase the accuracy: https://ledstrain.org/d/312-homemade-oscilloscope-to-detect-pwm-diy-guide/79

I found that CFLs are better for me spectrum-wise than regular White LEDs, however they usually do flicker a lot (100/120 Hz plus 20 kHz onwards, on top), causing flicker symptoms.

I think a major factor for eye strain can indeed be spectrum. I am very sensitive to White LEDs (the technology "White LED", not some "warm" or "cold" spec on the package) and have to turn the brightness all the way down. The few displays I'm comfortable with at high brightness have something in common: a spectrum consisting of narrow lines as opposed to having a rainbow spectrum. AMOLED and Quantum Dot. Of course, such displays become unusable when there's pixel flicker or backlight flicker going on, making it very hard to isolate spectrum as the single cause.
If I look at a CFL's spectrum I can see distinct lines there as well.

It would be interesting to find out how it is possible that spectrum has such a huge impact.

logixoul

KM I am very sensitive to White LEDs (the technology "White LED", not some "warm" or "cold" spec on the package)

Interesting!

I researched a bit, and found this:

An LED cannot emit white light naturally. However, use of certain technologies makes an LED to emit white light. There are three prevalent technologies to produce white light in LED and they are Wavelength Conversion, Colour Mixing, and a technology referred to as Homo-epitaxial ZnSe.

Which of the three are you sensitive to? (if you happen to know)

Also I forwarded your answer to my engineer friend.

ensete

CFL's were always brutal for me but my prediction came true and I almost never see them anymore. There are the worst option for lighting: If you care about light quality, you go incandescent or halogen, if you care about energy usage you go LED. CFL's has zero place in the lighting market.

logixoul

ensete

Interesting! Don't incandescent lights inherently flicker at 50/60Hz (with the AC electricity that comes from the wall)?

Also do you know why CFLs gave you eyestrain?

ensete

logixoul Interesting! Don't incandescent lights inherently flicker at 50/60Hz (with the AC electricity that comes from the wall)?

I am in the camp that firmly believe that "flicker/PWM" is a complete red herring and has nothing to do with our situation. Incandescent lights generate light through "black body radiation". This is the same way the sun makes light and our eyes, brains, and entire nervous system evolved to utilize that kind of a light source.

Also do you know why CFLs gave you eyestrain?

No one knows why any light/screen causes anyones symptoms here. It's all hunches and guesswork. I suspect it was the intensity of the light, since I have directly experience the same light both causing symptoms and not causing symptoms based on the intensity of the light source. I contacted a CFL manufacturer and talked to them and they explained that CFL's emit light at a much higher intensity because they need to make the same amount of light as a 4 foot long fluorescent tube in a smaller, thinner, wound up 2 foot one. Again, that is just a suspicion. Don't trust anyone who claims to "know" the underlying cause to any of our situations

KM

@ensete please speak for yourself and "your situation" but not for "our situation". There are people here who clearly suffer from flicker, and having to read statements like that is annoying.

ensete

KM Sorry, I meant "my situation". Although I suspect the failure several people have reported in alleviating their symptoms even after going down the flicker/dithering rabbit hole means I am not alone. Flickering is often quickly blames as "the" cause of our issues, without any actual data to back it up.