Author Topic: Someone is trying to argue that incandescent lamps don't have a CRI of 100.  (Read 2251 times)
HomeBrewLamps
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Someone is trying to argue that incandescent lamps don't have a CRI of 100. « on: January 30, 2021, 05:25:36 PM » Author: HomeBrewLamps
I don't know how many of you use quora. But so one made an insane comment on the site and I corrected them. Now I don't know how much of their comment is true about sunlight but I know for a fact
 That the general populous sees incandescent lamps as having a CRI of 100.

If anyone could lead me tk a proper source (other than Google top searches) that I can use to smash this guy. It'd be nice. I hate when people are this ignorant of a situation, and then spread their misinformation. I'd like scientific articles or something of the sort regarding CRI and incandescent lamps.. I would search myself hut I have things to do today..


https://www.quora.com/How-bright-are-led-light-bulbs/answer/Ryan-Carlyle?ch=10&share=5fc23a5b&srid=hys3f
« Last Edit: January 30, 2021, 05:38:21 PM by HomeBrewLamps » Logged

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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #1 on: January 30, 2021, 07:53:31 PM » Author: Binarix128
Wikipedia articles:

Black body
Black body radiation

A black body (in this case, an incandescent filament) will cover up all the visible spectrum if it is hot enough, and the temperature of operation of an incandescent bulb is more than enough, and it will cover up all the spectrum plus infrarred and some UVA uniformly, with an almost lineal decay, so, 100% CRI. Altought (mostly) LEDs cover up all the spectrum, they aren't 100% CRI, because they are composed by a bigger thin blue peak and a smaller and wide yellow peak, so the spectrum is not uniform and so not 100% CRI.

A black body emmiter is the only perfect emmiter for visible light applications, nor gas discharge, nor fluorescence (in LEDs and and mercury lamps) can (and difficultly will) create a light emmition just as a black body, they might cover up all the spectrum, but not uniformly enough.
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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #2 on: January 31, 2021, 12:39:05 AM » Author: Xytrell
Y'know how I respond to people like that?

"Interesting! I had always thought X because wikipedia says X. You would be doing a lot of people a favor if you correct this error for them and provide the requisite sources"

That shuts them up pretty quick. It also pre-emptively destroys any option for the standard retort of "you read it on wikipedia? Anyone can edit that you know."
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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #3 on: January 31, 2021, 04:03:20 AM » Author: AngryHorse
This is explained fully in Lamps And Lighting ( third edition ), but is really quite complicated!, and is split up into too many sections to list here, but depending on how they interpreted what they have read, they could actually be right in a way?, the section of, CIE standard illuminant, states that incandescent lamps conforms CLOSELY to that of a full radiator, not fully.
The readily-accepted standard for colour matching is ‘north skylight’, but like I say, it’s very complicated how it’s laid out in the book!
« Last Edit: January 31, 2021, 04:23:17 AM by AngryHorse » Logged

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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #4 on: January 31, 2021, 05:05:49 AM » Author: dor123
@HomeBrewLamps: You are a LG administrator and don't know that LG admins can't do anything with someones outside the website?
« Last Edit: January 31, 2021, 05:08:59 AM by dor123 » Logged

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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #5 on: January 31, 2021, 09:52:13 AM » Author: Binarix128
Y'know how I respond to people like that?

"Interesting! I had always thought X because wikipedia says X. You would be doing a lot of people a favor if you correct this error for them and provide the requisite sources"

That shuts them up pretty quick. It also pre-emptively destroys any option for the standard retort of "you read it on wikipedia? Anyone can edit that you know."
Not only because Wikipedia says it in this case (black bodies), but if you go to any physics book they will show the same.
« Last Edit: January 31, 2021, 09:56:01 AM by Binarix128 » Logged
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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #6 on: February 01, 2021, 03:08:47 AM » Author: Medved
The CRI100 is per definition the light of a black body. But to be tgat, the hot thing has to be black (so have emission coefficient of 1 over tge whole spectrum) and the light should not be obstructed by any filtring.

Real tungsten incandescent are thermal radiator, but the filament is reflecting some light, so its emission coefficient is not 1. If the emission coefficient would be the same acros the spectrum, the radiation would be weaker but still retain its CRI100. But the real incandescent always has microscopic texture on the tungsten surface, which forms resonant peaks and valeys, making the overall emission coefficient uneven. This tgen translates into small peak and valeys in the radiated spectrum.

Some even tried to harness this effect in order to suppress the radiation in the IR, hence boost the efficacy in visible, by deliberately forming the required structure on the tungsten surface. But the problems was mainly the inability to make that structure last (the evaporation tend to affect to eat away those peaks) and the effects extending into visible, so affecting the CRI.

So yes, incandescent technically do not have exactly CRI100, but claiming some energy band transfer emission based source (all nonthermal sources) has it any better or even close to the incandescent is just obviously nonsense...
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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #7 on: February 01, 2021, 06:03:30 AM » Author: dor123
I've never seen emission or absorption lines in the spectrum of incandescent and halogen lamps
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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #8 on: February 01, 2021, 10:34:19 AM » Author: Binarix128


(Pics took from an ElectroBOOM video)

@Medved: That effect might be present, but the gitter created is not enough to create a huge difference that can affect the CRI, so it still covers up the whole spectrum smoothly in a single peak with minimal gitter. Also, that spectrum was tested in sketchy conditions, in an open room with some sunlight going inside, so the spectrum is smoother than that. So we can still say that it is still 100 CRI.

Also a perfect black body is a theorical object, in real life nothing is a perfect black body. So we can still consider the incandescent filament as one altought it is not perfect.

Even at cloudy days the spectrum of the sun is almost 100 CRI covering all the spectrum with a single peak at green but with some gitter due to the gas absorptions.
« Last Edit: February 01, 2021, 10:39:23 AM by Binarix128 » Logged
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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #9 on: February 01, 2021, 11:27:51 AM » Author: alexd120
 I don't know to much about incandescent bulbs
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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #10 on: February 01, 2021, 11:49:45 AM » Author: Medved
I've never seen emission or absorption lines in the spectrum of incandescent and halogen lamps

It is the small rippling along the spectrum, plus slight deformation of the curve. Practically it has no influence on whatsoever, but rigorously speaking it is there, so not the exact CRI100.

The effect is barely measurable, indeed, that is why I said there is no way any non thermal radiation would be able to go as close to the CRI100 as the incandescent.
For the 5600K the situation is questionable, because per definition the CRI100 is the daylight, but the daylight is quite ripply.
So in the theory, if you would have a black body at that temperature, it would have CRI above 100 (or less than 100? I dunno how that should be treated).
But again, we are talking about differences that may be possible to measure, but for real life illumination can not have any effect whatsoever.
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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #11 on: February 02, 2021, 03:33:30 PM » Author: HomeBrewLamps
Here is there latest response lol. I hate people sometimes. Especially ones who are "ignorant and proud"

Also to clarify. When I said 15 years of experience that means from when I was 6 onwards. Because I've been screwing around with lights since then. Not professional experience no. But I've been learning since then and know far more than this dude.
« Last Edit: February 02, 2021, 03:36:51 PM by HomeBrewLamps » Logged

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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #12 on: February 02, 2021, 05:21:35 PM » Author: CreeRSW207
Here is there latest response lol. I hate people sometimes. Especially ones who are "ignorant and proud"

Also to clarify. When I said 15 years of experience that means from when I was 6 onwards. Because I've been screwing around with lights since then. Not professional experience no. But I've been learning since then and know far more than this dude.
Good slam. Did he give up after that?I hate when know it all people try to ruin everything.
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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #13 on: February 03, 2021, 02:18:00 AM » Author: dor123
White LED can't reach Ra=98, The maximum value they can reach is 90, because of their spectra.
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Re: Someone is trying to argue that incandescent lamps don't have a CRI of 100. « Reply #14 on: February 04, 2021, 04:14:32 AM » Author: Medved
White LED can't reach Ra=98, The maximum value they can reach is 90, because of their spectra.

What makes you think the LED spectrum can not be shaped so it reaches the CRI98?
E.g. assembling the dies with varying wavelength to spread the blue peak you so like to hate... :-)
Yes, such creation would be ridiculously expensive, fiddly and maybe even not that much efficient.
Would it make any practical sense? No. Except maybe satisfying some "purist"...
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