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As I have mentioned elsewhere I have painted the reflecting part of the shades in blue. The LED light looks even bluer that before. I had read that blue light aids concentration.

CRI is color rendition index. The colors we see are a result of the objects ability to reflect certain wavelengths back, However if those wavelengths are not present in the first place then color can look off. The CRI scale goes from -100 to 100. -100 is pure monochrome, (Laser light) and 100 is sun light/incandescent. The closer your bulb is, the more natural colors will look because the light from the bulb is more balanced over the spectrum relative to natural light.
For something like lighting a room I would go no lower than 80+. (really 85+ if you can find it). For kitchens/places you eat or places like a vanity mirror setup I would say 90+ really 95+.

Often such 95+ CRI bulbs cost a fortune, so my solution is to get the lower CRI rated ones and supplement them with incandescent, after all the LED is pulling 10% of the power, so you are still cutting power draw by nearly 50% (I made my parents go with 4 LED and 2 incandescent in out dining room chandelier, that worked out really well and uses only 144W now as opposed to the original 360W)

TL I am guessing is Tube light or a term for Fluorescent?

The main thing to watch out on with LEDs is their strobe. Cheap LEDs lack smoothing capacitors or use half wave rectification, and thus the strobe effect can be quite noticeable. There is no good way to know without testing the bulb, I have dropped fair sums of money on bulbs only to be be disappointed by the strobe.

For LEDs that look like normal bulbs I recommend Greenlight LEDX (or any LED filament based bulb (jsut watch out for strobe)), for ceiling based accent lighting there is Soraa, they have some wonderful high CRI bulbs but be prepared to pay the premium.


As for lighting that helps sight reading, yes such a thing does exist. I have played around with low pressure sodium lighting (-44CRI effectively pure monochrome yellow) and while it drains any sense of color perception from the room, it renders black text on white super clearly. (ever wonder why caution signs are black text on yellow?) I am sure there are less extreme varieties of lighting that could work, but likely not as well.


Sorry for the wall of text, Lighting is something I really care about, spending some time and money to get the right setup can really make huge differences on your daily life.

I have a suspicion -- not backed up by evidence -- that some of the bias I have against LED bulbs is this strobe/flicker effect, even though I can't directly perceive it. I can't see the flicker whilst looking at something directly illuminated (and I suspect that nobody can, because human persistence of vision is too long); but I can see it when I move my eyes rapidly around the illuminated object. That makes me wonder whether I might be unconsciously aware of it at other times as well.

Although I can't consciously perceive the flicker, I wonder whether it does affect me in some subliminal way.

If you can see the flicker when you are not looking directly at the lights, you are still perceiving it. My experience is that LED bulbs have improved greatly in this regard.

The first year that LED holiday lights were available we tried some and they lasted less than an hour in my house because they were an instant migraine for me.

Yes, that is when I am most aware of flicker, when I turn my head, or move my eyes quickly. But I also can notice it while not moving it is just much tougher. one good test is to wave your hand in front of the bulb. if you see distinct striated blurs then there is strobe.

Strobe from cheap bulbs can lead to eye fatigue, and if it is really bad, I can get a headache.

Yes CRI and TL as XenondiFluoride wrote. tube light / flurescent.

Halogen and incandescent have very high light quality / CRI but very reddish, like a sunset.

I see almost all flicker. Some cars today have flickering rear lights, I can't see these cars properly, I just see red spots scattered around. Some fluorescent lamps also flicker, I think it's something wrong in the electronics or maybe cheap electronics. They also use flickering displays eg on buses, information boards, etc. Again, I see just a cloud of flickering light if I'm moving relative to that...

> am using the lights to read black ink on white paper. Does the colour of the light matter?

Not much. But in the evening be careful with blueish light, it may disturb your internal clock and your sleeping. Better use warm white. And of course different lights have different whites, so you can get pinkish, bluish and yellowish spots if you mix lights with different color temperatures in your room.

You likely have better eyes than I do, I can see a little past 60Hz but not much, so I'll notice strobe fairly easily if I am looking for it, or if it is on the bad side. It sounds like you are able to pick it out much better.

Peripheral vision is more sensitive to strobe than central vision, because our prehistoric ancestors needed to be more sensitive to motion there, where predators might come from. Look at something about 60 - 80 degrees away from the light and most people can pick up 50 - 60 Hz. strobe. The finger wave test works well.

People who grew up in the 50 Hz countries back in the CRT days have developed the ability to ignore strobe because they watched 50 Hz TV. (BTW, the actual fluorescent and LED strobe frequencies are 100 and 120 Hz, because light is produced on both the positive and negative half cycles, they go dark around the zero crossings.)

LED's and CFL's today mostly use electronics to strobe them somewhere in the tens of kilohertz, which nobody can see. You need a camera with a high frame rate and small shutter angle to pick it up. The main source for power line strobe now is fluorescent tubes on old time magnetic ballasts, which are mostly over 10 - 20 years old. Manufacturing of magnetic ballasts was banned in the U.S. in 2009, most makers and electrical contractors converted well ahead of the deadline.

I never imagined I would learn so much from such a simple post! Than you everybody.

I don't know if I believe this, but here's an interesting study:

https://tinyurl.com/y8a3hfpp

It's about how LEDs can hurt your eyes. I tried the recommended computer application called "IRIS" - made the screen look really dark and weird, but my eyes did feel better. Just can't do any kind of color processing with it.

Gotta wonder sometimes- there seems to always be a possible drawback to new technology that isn't discovered until a number of people are injured. As I mentioned- not so sure about this particular case.

I like the old Mr. Blue full spectrum lights or Ott lights, but I use LEDS for most of my overheads.

There's an ongoing debate about whether too little red, or too much blue, light is the problem. Or both, or neither. There is some scant evidence that short-wavelength visible blue light in the 420nM range can cause some retinal cell damage, and this has been put forward as a contributory factor in age-related macular degeneration. The evidence was strong enough for me to pay an extra £10 to have a filter coating applied to my spectacles to block light in that region, but I don't know that the evidence is strong enough for a major lifestyle change.

I don't believe it. If IR from incandescents and candles really makes that big a difference, how did our ancestors survive before they had fire? If you want loads of IR, far more than a house full of incandescents can produce, just get one of those little plug-in heaters that go under your desk.

I am another Californian who can buy subsidized LED bulbs. Our local DAISO, the Japanese 100 yen store or $1.50 here, sells a range of bulbs for $2. They are dimmable, 2700K, CRI>90, and R9>50. That last is a measure of how much red light is put out, which is important for making food look good.

I did have one problem. I was fixing a paper shredder and when I went to test the paper detection by shining my desk lamp on the light detector nothing happened. After a few minutes of scratching my head it dawned on me. It detects infrared from a silicon LED. Shining an incandescent flashlight (torch) worked.

Well that is how they *are* supposed to work and why they are efficient.