LED lightbulbs

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Valuethinker
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Re: LED lightbulbs

Post by Valuethinker » Sat Sep 12, 2015 1:54 am

bertilak wrote:I have yet to finds LED bulb that dims as nicely as good old-fashioned incandescents, nor do they last as long as advertised.

A couple of years back the LEDs labeled "dimable" did respond to the slider on the dimmer but what they did was switch at the halfway point from full-on to full-off. Lowes gave me a full refund.

Newer ones are better but require a special dimmer. I installed one at $27 and it does work fairly well, but it never gets anywhere near as dim as an incandescent. I have a LOT of dimmers in my house so am still using incandescent everywhere but the one place I put in that $27 dimmer.

You can still find 60 watt incandescents even though they are no longer allowed. There are loopholes for specialty bulbs. I like the ones designated for harsh environments, like vibrations. They do cost more than in the old days.

But things seem to change almost weekly. I am running low so need to go and figure out (all over again) what to buy. It used to be so easy and cheap to get light bulbs. Now you need to live with whatever you get for $5-$20 per bulb or make it a major research project every year or so.

Yeah, and forget that "lasts 22 years" promise on the box. I find they generally fail in about a year, maybe a bit longer. Blows a big hole in the "saves money in the long run" theory! I think the small print on the box says that the 22 years is based on a pretty short duty cycle of only a few hours a day.

Halogen's also work reasonably well and are available "legally" but are also expensive.
I am sorry you have had bad experiences with LED bulbs with dimmers. Those are the halogens in the house that I have not replaced (the ones on a dimmer switch) but they are only on a very few hours/ day. Also a 300w halogen uplighter (when it's on, it uses roughly as much energy as all the other lightbulbs in the house, combined).

I can confirm however, at least with the Philips bulbs and 50HZ 220v AC, that the bulbs last a long time. Other than one I have dropped, I have only had to replace one bulb in about 40, over 3 years (note when I started this thread).

My electricity consumption dropped about 20% when I did this, and I have been unable to identify another explanation why that happened (I was using around 60 kwhr/ week, now use around 50/ kwhr although more in winter).

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Re: LED lightbulbs

Post by madbrain » Sat Sep 12, 2015 3:14 am

bertilak,
bertilak wrote: Yeah, and forget that "lasts 22 years" promise on the box. I find they generally fail in about a year, maybe a bit longer. Blows a big hole in the "saves money in the long run" theory! I think the small print on the box says that the 22 years is based on a pretty short duty cycle of only a few hours a day.

Halogen's also work reasonably well and are available "legally" but are also expensive.
Frankly, I have never had an LED light bulb fail yet. I am very surprised you would get a failure at a year. Definitely seems like bad luck.
I have about 250 lightbulbs in my home. When we moved in 5 years ago, I put CFLs everywhere.
About 15% of those have failed now and have been replaced with LEDs. Almost of the LEDs are FEIT from Costco which carry a warranty of several years .

I write the date with a market on each LED I have put in service. And I have actually scanned several of my Costco receipts for the LEDs in case they fail early. But even if I did not, I should still be able to get a proof of purchase years later based on the in-service date. I usually don't buy these bulbs ahead of replacement time, since they are expensive and prices are dropping.

If you have had LEDs fail at one year, most likely they are covered by the warranty. I would contact the manufacturer for a free replacement.

Note that even if the LEDs do last 22 years, they are still not very competitive with CFLs on purely bulb cost.

For example :
http://www.costco.com/CatalogSearch?sto ... yword=br30

The pre-rebate price of those BR30 LED bulbs is $10/bulb . These have a 25,000 hour life.
BR30 CFL bulbs are $2.92/bulb. These have a 10,000 hour life.
Both put out the same amount of light, 750 lumens.

Ie. the LEDs cost 3.4x as much as the CFLs, but only last 2.5x as long.

The cost difference of the LED has to be earned back in terms of power savings. That can take a while.

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bertilak
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Re: LED lightbulbs

Post by bertilak » Sat Sep 12, 2015 5:10 am

Thanks for the tea and sympathy over my bad LED experiences!

About early failures: I thought a bit about this. I do have several LEDs that have been working for a very long time now. The ones that have failed are in a few ceiling fixtures that are very close to my AC/propane furnace in the attic. When that runs it does vibrate quite a bit. I wonder if that contributes to early life failures. Those bulbs are also ones that happen to be on a lot. Of course LEDs haven't even been around for 22 years so the jury is still out, and will be for along time.

About dimmers: My experience has been rather poor and I think the problem is that the LED bulb technology is just not there yet.

About costs: IF the LEDs worked as well as incandescents I would be OK with them even if they never paid back 100% just for the convenience of not having to change them as often. (I have some high ceilings!) CFLs I can't stand. Too harsh. The number of CFLs on display at stores seems to be shrinking so I think LEDs are on the way to replacing them.
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just frank
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Re: LED lightbulbs

Post by just frank » Sat Sep 12, 2015 5:58 am

bertilak wrote:Thanks for the tea and sympathy over my bad LED experiences!

About early failures: I thought a bit about this. I do have several LEDs that have been working for a very long time now. The ones that have failed are in a few ceiling fixtures that are very close to my AC/propane furnace in the attic. When that runs it does vibrate quite a bit. I wonder if that contributes to early life failures. Those bulbs are also ones that happen to be on a lot. Of course LEDs haven't even been around for 22 years so the jury is still out, and will be for along time.

About dimmers: My experience has been rather poor and I think the problem is that the LED bulb technology is just not there yet.

About costs: IF the LEDs worked as well as incandescents I would be OK with them even if they never paid back 100% just for the convenience of not having to change them as often. (I have some high ceilings!) CFLs I can't stand. Too harsh. The number of CFLs on display at stores seems to be shrinking so I think LEDs are on the way to replacing them.
Those ceiling can fixtures are likely your problem with LEDs...the trapped heat is really tough on any non-incandescent technology. I had my struggles with my own can lights over the years.

The LED 'edison type' bulbs are much cheaper, and are durable/dimmable in conventional fixtures.

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Re: LED lightbulbs

Post by bertilak » Sat Sep 12, 2015 8:12 am

just frank wrote:The LED 'edison type' bulbs are much cheaper, and are durable/dimmable in conventional fixtures.
Just ordered a couple of Edison Bulbs to try out. Maybe this is the Holy Grail!
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Re: LED lightbulbs

Post by just frank » Sat Sep 12, 2015 8:33 am

bertilak wrote:
just frank wrote:The LED 'edison type' bulbs are much cheaper, and are durable/dimmable in conventional fixtures.
Just ordered a couple of Edison Bulbs to try out. Maybe this is the Holy Grail!
I was unclear, and thinking all omni-directional LED bulbs were pretty ok (name brands like Cree and Phillips).

That said, I am a big fan of the filament LEDs. I think they are the future of the technology. Rather than having a big metal (expensive, ugly) heat sink, they fill a glass bulb with helium gas, and the high thermal conductivity of the helium keeps the LEDs in the filament cool. The filament approach also lets the light escape, and so buys a bit more lumens per W. (The one you ordered is 115 lum/W, which is almost 2x better than CFL).

info: http://www.greenbuildingadvisor.com/blo ... ment-bulbs

Can't speak to the filament LEDs durability though, a lot of them come from no-name sources in China. I do have one that has been working well for a year or so.

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Re: LED lightbulbs

Post by bertilak » Sat Sep 12, 2015 8:51 am

just frank wrote:
bertilak wrote:
just frank wrote:The LED 'edison type' bulbs are much cheaper, and are durable/dimmable in conventional fixtures.
Just ordered a couple of Edison Bulbs to try out. Maybe this is the Holy Grail!
I was unclear, and thinking all omni-directional LED bulbs being pretty ok (name brands like Cree and Phillips).

That said, I am a big fan of the filament LEDs. I think they are the future of the technology. Rather than having a big metal (expensive, ugly) heat sink, they fill a glass bulb with helium gas, and the high thermal conductivity of the helium keeps the LEDs in the filament cool. The filament approach also lets the light escape, and so buys a bit more lumens per W. (The one you ordered is 115 lum/W, which is almost 2x better than CFL).

Can't speak to the filament LEDs durability though, a lot of them come from no-name sources in China. I do have one that has been working well for a year or so.
My understanding of the reason LEDs outlast incandescents is that by their very nature incandescents "use up" the filament. Molecules "boil off." Not sure what the limiting factor is for LEDs (whether implemented in the shape of a filament or not) other than the general principle that things wear out: Second law of thermodynamics? Entropy? Imperfect translation from theory to practice?
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just frank
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Re: LED lightbulbs

Post by just frank » Sat Sep 12, 2015 9:12 am

bertilak wrote:My understanding of the reason LEDs outlast incandescents is that by their very nature incandescents "use up" the filament. Molecules "boil off." Not sure what the limiting factor is for LEDs (whether implemented in the shape of a filament or not) other than the general principle that things wear out: Second law of thermodynamics? Entropy? Imperfect translation from theory to practice?
Indeed. The lifetime of incandescents is inversely proportional to the filament temp (and thus the efficiency). Think about those 100 year old incandescents you hear about: they are dimmed to a very pale glow. Those 'long-life' bulbs they used to sell? Just ran cooler (and much lower lum/W). Putting halogens in the bulb effectively slows the evaporation process, allowing higher temps (and thus whiter, brighter incandescents) and slightly higher lum/W.

With the LEDs it seems the emitters and phosphors are usually good for 50,000 hours (but might gradually fade 20% over that period). I don't know the limiting process, but 6 years continuous is pretty nice. The bigger problem is the cheapo electronics they use to turn AC into DC for the LEDs...those can fritz out in no time due to poor manufacturing practices or quality control. I hear one factor is using cheap electrolytic capacitors that literally 'dry out' and fail (faster at higher temps of course), rather than using more expensive capacitors based on Tantalum.

So, in conclusion, I think LED bulbs from China might have the same emitters (and emitter longevity) as those from Philips or Cree (who make both bulbs and emitters), but I trust the name brands to engineer the power supplies for better durability.
Last edited by just frank on Sat Sep 12, 2015 11:21 am, edited 2 times in total.

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Re: LED lightbulbs

Post by dbr » Sat Sep 12, 2015 9:13 am

The dimmers I use on my LEDs have an adjustment screw that allows the "low" setting to be adjusted to just where the LED turns off. Without this it is difficult to truly dim an LED. They are by Lutron I think. The situation is still not quite perfect as incandescent bulbs when they dim also shift to warmer color spectrum which LEDs do not.

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Re: LED lightbulbs

Post by bertilak » Sat Sep 12, 2015 9:27 am

dbr wrote:The dimmers I use on my LEDs have an adjustment screw that allows the "low" setting to be adjusted to just where the LED turns off. Without this it is difficult to truly dim an LED. They are by Lutron I think. The situation is still not quite perfect as incandescent bulbs when they dim also shift to warmer color spectrum which LEDs do not.
That's exactly the dimmer I have but it doesn't give me a full range of adjustment. Can't get it to "almost off." I decided to leave it installed because it was "barely acceptable" since I really don't dim things to that point. I was thinking of leaving a super-dimmed bulb as a night light but it is now too bright for that. I can live without that but it certainly is no credit to the technology.
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Re: LED lightbulbs

Post by dbr » Sat Sep 12, 2015 9:49 am

bertilak wrote:
dbr wrote:The dimmers I use on my LEDs have an adjustment screw that allows the "low" setting to be adjusted to just where the LED turns off. Without this it is difficult to truly dim an LED. They are by Lutron I think. The situation is still not quite perfect as incandescent bulbs when they dim also shift to warmer color spectrum which LEDs do not.
That's exactly the dimmer I have but it doesn't give me a full range of adjustment. Can't get it to "almost off." I decided to leave it installed because it was "barely acceptable" since I really don't dim things to that point. I was thinking of leaving a super-dimmed bulb as a night light but it is now too bright for that. I can live without that but it certainly is no credit to the technology.
Curious, maybe it is also a question of which bulb. I would have to go back and find out, but I definitely have the setting at "almost off." There is also the issue of how bright the bulb is in the first place. That is, how bright does the bulb need to be at full on. I am using 60w equivalents as single bulbs. Things might be more difficult with a brighter bulb or in a multi-bulb fixture.

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Re: LED lightbulbs

Post by canderson » Sat Sep 12, 2015 11:09 am

We've had three Cree LED bulbs fail in the past month, all less than 1 year old. They've strobes (flashing on/of repeatably), flickered constantly and the third got so hot I felt it from 2' away on the couch.

We took them back abd got Phillips instead. Hope or better luck from the other 14 Cree bulbs we have.

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Re: LED lightbulbs

Post by deanbrew » Sat Sep 12, 2015 12:40 pm

I've had mixed success with LED bulbs. I had two burn out in my office in a year. I also bought a bunch of CREE floodlights last summer to set up a storeroom, and I've had to replace seven out of 48 within the first year. That's a pretty dismal failure rate. They are installed in standard can recessed light fixtures. I don't buy the temperature excuse, as it seems that this is the exact intended use for a BR30 bulb. A couple of the failures occurred within a couple of months, and I thought the rest would be OK, but there have been periodic failures since then. Thankfully, Home Depot has been really good about replacing the bad ones. They don't even ask to see the receipt.

I just bought a pretty expensive dimmable 100W-equivalent LED standard-shape bulb for my kitchen. I hope I have better luck with it, and I'd like to replace some more 100W bulbs, but I'd like to see the cost come down.
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Re: LED lightbulbs

Post by anoop » Sun Apr 28, 2019 1:06 am

I find it pretty frustrating that most bulb manufacturers don't seem to include the CRI on the package.

In general, LEDs make shopping for bulbs really hard. With incandescents, all we had to do was pick the wattage (for the standard bulb size). Didn't really have to worry about dimmable, color temperature, lumens, or CRI. And there was always a decent supply of all wattages available.

Nowadays, even a place like a Lowes or a Home Depot barely has any selection of LEDs, especially if one is looking for something like a 100 W equivalent.

I just had one of my floor lamps break (which uses 2x150W incandescents), and I'm having so much trouble finding a decent replacements. I don't think there is a such a thing as a 150W eq LED with a decent CRI (ideally 90+) that can be used in a torchiere with 2 bulbs.

(BTW, is it better to resurrect an old thread or start new ones?)

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Bogle7
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Re: LED lightbulbs

Post by Bogle7 » Sun Apr 28, 2019 1:18 am

1000bulbs.com is my go to for exotic lamps.
For example, https://www.1000bulbs.com/category/3000 ... t-a-lamps/

They have knowledgeable humans you can talk with.
Also, sometimes, bulbs are available on Amazon—as sold and shipped by 1000bulbs—with free shipping.
Last edited by Bogle7 on Sun Apr 28, 2019 8:47 am, edited 1 time in total.

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Re: LED lightbulbs

Post by astrohip » Sun Apr 28, 2019 7:00 am

Bogle7 wrote:
Sun Apr 28, 2019 1:18 am
1000bulbs.com is my go to for exotic lamps.
For example, https://www.1000bulbs.com/category/3000 ... t-a-lamps/
I second 1000bulbs. Not only do they have a great selection, many (most?) of their bulbs have all the info listed--from the std like lumens & Kelvin, to the more obscure such as CRI, Beam Angle, etc.

I replaced all 75 or so bulbs in my house thru them. Including weird little vanity bulbs, vent-hood halogen>LED replacements, and more.

Good luck and happy bulb hunting!
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Re: LED lightbulbs

Post by WWV » Sun Apr 28, 2019 11:48 am

anoop wrote:
Sun Apr 28, 2019 1:06 am
I find it pretty frustrating that most bulb manufacturers don't seem to include the CRI on the package.
Roger that.

Recently tried to get the CRI for GE LED reveal bulbs. Asked for this on "Q&A" big box website, also sent message to GE from their website. Still waiting...

UPDATE-GE replied
Thank you for contacting GE Lighting. I am happy to assist you.

We appreciate your interest in our Company and our products. In response to your question

What is the CRI for this bulb?


Model # 30688


GE Reveal 65-Watt EQ LED Br30 Color-Enhancing Dimmable Spotlight Light Bulb

--the Reveal HD+ is 95+CRI.

--The Refresh and Relax HD are 90+ CRI.
Cree lists "90+" on the front of their box. They also clearly state Ok for enclosed fixtures. They are on the shelf at Home Depot
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Re: LED lightbulbs

Post by anoop » Sun Apr 28, 2019 1:08 pm

astrohip wrote:
Sun Apr 28, 2019 7:00 am
Good luck and happy bulb hunting!
Not just bulbs, the floor lamp too.
WWV wrote:
Sun Apr 28, 2019 11:48 am
Cree lists "90+" on the front of their box. They also clearly state Ok for enclosed fixtures. They are on the shelf at Home Depot
Thanks for the pointer.

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Re: LED lightbulbs

Post by Teague » Sun Apr 28, 2019 1:43 pm

anoop wrote:
Sun Apr 28, 2019 1:06 am
I find it pretty frustrating that most bulb manufacturers don't seem to include the CRI on the package.
Well, then the "good" news is that CRI isn't really as meaningful as one might hope. For one thing, the color references used in that standard are all desaturated, and there are several other problems. So a CRI of 90 is kind of like saying that a light source scored 90% when measured by a standard which itself is only 70% accurate.
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Re: LED lightbulbs

Post by anoop » Sun Apr 28, 2019 1:50 pm

Teague wrote:
Sun Apr 28, 2019 1:43 pm
Well, then the "good" news is that CRI isn't really as meaningful as one might hope. For one thing, the color references used in that standard are all desaturated, and there are several other problems. So a CRI of 90 is kind of like saying that a light source scored 90% when measured by a standard which itself is only 70% accurate.
What is the alternative? Are there any other metrics? Or just live with whatever light quality we get if we ignore the CRI?

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Re: LED lightbulbs

Post by Teague » Sun Apr 28, 2019 2:12 pm

anoop wrote:
Sun Apr 28, 2019 1:50 pm
Teague wrote:
Sun Apr 28, 2019 1:43 pm
Well, then the "good" news is that CRI isn't really as meaningful as one might hope. For one thing, the color references used in that standard are all desaturated, and there are several other problems. So a CRI of 90 is kind of like saying that a light source scored 90% when measured by a standard which itself is only 70% accurate.
What is the alternative? Are there any other metrics? Or just live with whatever light quality we get if we ignore the CRI?
There are alternative standards that are better. Unfortunately, they are not in wide usage, so of little use to most of us. There's one called R9 for residential lighting, and another called TLCI for video. But even they are not perfect (though better). There's one called TM-30-15 that uses 99 color samples vs. 8 color samples for CRI, but it is not commonly used. So we are kind of stuck with CRI for the moment as the most available measurement of light "quality." It's not such a good standard but probably better than nothing, at least usually.
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Re: LED lightbulbs

Post by iamlucky13 » Mon Apr 29, 2019 3:11 am

anoop wrote:
Sun Apr 28, 2019 1:06 am
I find it pretty frustrating that most bulb manufacturers don't seem to include the CRI on the package.

In general, LEDs make shopping for bulbs really hard. With incandescents, all we had to do was pick the wattage (for the standard bulb size). Didn't really have to worry about dimmable, color temperature, lumens, or CRI. And there was always a decent supply of all wattages available.

Nowadays, even a place like a Lowes or a Home Depot barely has any selection of LEDs, especially if one is looking for something like a 100 W equivalent.

I just had one of my floor lamps break (which uses 2x150W incandescents), and I'm having so much trouble finding a decent replacements. I don't think there is a such a thing as a 150W eq LED with a decent CRI (ideally 90+) that can be used in a torchiere with 2 bulbs.

(BTW, is it better to resurrect an old thread or start new ones?)
The lamp might be repairable. A lot of fixtures use interchangeable parts, which home improvement and hardware stores usually sell.

If it's not, you might be able to find a 3-socket lamp: 3 x 1600 lumen bulbs (100W equivalent) will produce basically the same amount of light as 2 x 2500 lumen bulbs (150W equivalent). I believe you can find 100W equivalent, 90+ CRI bulbs from Cree, Feit, and Hyperikon. The last brand I've only seen sold online, but they're making a good name for themselves.

Shop mainly based on lumens, not wattage. A 150W incandescent produces about 2000-2500 lumens, depending whether it is a short-life or extended life bulb.

I would not say shopping for incandescents was better, except for the universality of dimming and enclosed-fixture compatibility. You had only 1 or in some form factors 2 color temperature choices (standard or halogen bulbs). Marketing based on wattage hid the fact that 60W bulbs, for example, could vary between 600 and 850 lumens.

Lowes and Home Depot have huge selections of LED's - more than they ever had of incandescent. It's just that there is no bulb that combines all of the best features of LED's without having some of the drawbacks (eg - high CRI, but not suitable for enclosed fixtures), and a lot of the options are different form factors or color temperatures. I guess it's a form of the "tyranny of choice."

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Re: LED lightbulbs

Post by iamlucky13 » Mon Apr 29, 2019 3:20 am

Teague wrote:
Sun Apr 28, 2019 1:43 pm
anoop wrote:
Sun Apr 28, 2019 1:06 am
I find it pretty frustrating that most bulb manufacturers don't seem to include the CRI on the package.
Well, then the "good" news is that CRI isn't really as meaningful as one might hope. For one thing, the color references used in that standard are all desaturated, and there are several other problems. So a CRI of 90 is kind of like saying that a light source scored 90% when measured by a standard which itself is only 70% accurate.
It's not the accuracy that is the issue, but the limited scope of the test. An 8 question test (like CRI) that covers a few very different topics can tell you something about the breadth of a student's of knowledge, but a 99 question test (like the newer TM-30-15) can help you better understand exactly what aspects of each topic they should learn more about. In either case, however, if you only report the student scored 75%, you don't convey any more clear information about the student from the 8 question test than the 99 question test.

With respect to the phosphor-converted LED's that comprise nearly all white LED lights, that's much less of a problem in practice than it was with the spiky spectral output of fluorescents. The smoother spectra of LED's make it more difficult to game the test. The weaknesses of LED's with respect to CRI happen in the same parts of the spectrum (a little bit in the blue-green and violet ranges, but mostly in the deep reds) almost universally.

Although CRI's Ra score does not use saturated samples in the calculation, there are saturated samples that are measured. R9 is generally the most interesting one, assessing saturated red. This common weak zone in LED lights is important, because it heavily affects the appearance of skin and wood tones. With LED's there is good correlation between increasing CRI score and increasing R9 score.

There are several newer standards. Color Quality Scale is perhaps a bit more useful in that it more strongly penalizes scores when a small number of samples score very poorly, but it hasn't really caught on.

TM-30-15 is gaining traction, but it's a very complex test.

Of the various metrics included in TM-30-15, Rf is very similar to Ra in the CRI test, but although it uses far more samples (99 vs. 8), unless a significant number of samples have poor performance indicating gaps in the spectrum, Rf scores will be pretty similar to CRI Ra scores. Understanding TM-30-15 well enough to take advantage of its benefits is not consumer-level endeavor, but assessing only the Rf score has the drawbacks of reporting a single number like the student's test grade example in my first paragraph.

To sum it all up: if you're comparing LED's to LED's, CRI is a fairly reasonable metric to use for comparison for general purpose lighting.

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Valuethinker
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Re: LED lightbulbs

Post by Valuethinker » Mon Apr 29, 2019 3:40 am

iamlucky13 wrote:
Mon Apr 29, 2019 3:20 am
Teague wrote:
Sun Apr 28, 2019 1:43 pm
anoop wrote:
Sun Apr 28, 2019 1:06 am
I find it pretty frustrating that most bulb manufacturers don't seem to include the CRI on the package.
Well, then the "good" news is that CRI isn't really as meaningful as one might hope. For one thing, the color references used in that standard are all desaturated, and there are several other problems. So a CRI of 90 is kind of like saying that a light source scored 90% when measured by a standard which itself is only 70% accurate.
It's not the accuracy that is the issue, but the limited scope of the test. An 8 question test (like CRI) that covers a few very different topics can tell you something about the breadth of a student's of knowledge, but a 99 question test (like the newer TM-30-15) can help you better understand exactly what aspects of each topic they should learn more about. In either case, however, if you only report the student scored 75%, you don't convey any more clear information about the student from the 8 question test than the 99 question test.

With respect to the phosphor-converted LED's that comprise nearly all white LED lights, that's much less of a problem in practice than it was with the spiky spectral output of fluorescents. The smoother spectra of LED's make it more difficult to game the test. The weaknesses of LED's with respect to CRI happen in the same parts of the spectrum (a little bit in the blue-green and violet ranges, but mostly in the deep reds) almost universally.

Although CRI's Ra score does not use saturated samples in the calculation, there are saturated samples that are measured. R9 is generally the most interesting one, assessing saturated red. This common weak zone in LED lights is important, because it heavily affects the appearance of skin and wood tones. With LED's there is good correlation between increasing CRI score and increasing R9 score.

There are several newer standards. Color Quality Scale is perhaps a bit more useful in that it more strongly penalizes scores when a small number of samples score very poorly, but it hasn't really caught on.

TM-30-15 is gaining traction, but it's a very complex test.

Of the various metrics included in TM-30-15, Rf is very similar to Ra in the CRI test, but although it uses far more samples (99 vs. 8), unless a significant number of samples have poor performance indicating gaps in the spectrum, Rf scores will be pretty similar to CRI Ra scores. Understanding TM-30-15 well enough to take advantage of its benefits is not consumer-level endeavor, but assessing only the Rf score has the drawbacks of reporting a single number like the student's test grade example in my first paragraph.

To sum it all up: if you're comparing LED's to LED's, CRI is a fairly reasonable metric to use for comparison for general purpose lighting.
The breadth of knowledge (and depth) never ceases to astound me.

Thank you.

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