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Author Topic: CFL vs. LED vs Daylight spectrum.  (Read 2318 times)

Redcrown

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CFL vs. LED vs Daylight spectrum.
« on: November 03, 2015, 12:26:32 am »

This is interesting. Guy uses a CD/DVD disk as a prism to show the spectrum of daylight vs. CFL vs. LED light sources. That part is the first 3 minutes. The rest is about wiring and not relevant.

Not sure what to think of it? 

https://www.youtube.com/watch?v=EoAZ-u6hn6g
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Bart_van_der_Wolf

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Re: CFL vs. LED vs Daylight spectrum.
« Reply #1 on: November 03, 2015, 07:32:57 am »

This is interesting. Guy uses a CD/DVD disk as a prism to show the spectrum of daylight vs. CFL vs. LED light sources. That part is the first 3 minutes. The rest is about wiring and not relevant.

Not sure what to think of it?

Well, it give a good impression of how continuous the illuminant's spectrum looks to the human eye (color sensitivity imperfections included).

Cheers,
Bart
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digitaldog

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Re: CFL vs. LED vs Daylight spectrum.
« Reply #2 on: November 03, 2015, 10:17:35 am »

As they used to say on Laugh in on TV: Very interesting but stupid  ;D


If you want to examine the spectrum of an illuminant, use a Spectrophotometer and good software to plot it.
http://www.ppmag.com/reviews/200604_rodneycm.pdf
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xpatUSA

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Re: CFL vs. LED vs Daylight spectrum.
« Reply #3 on: November 08, 2015, 10:26:54 am »

This is interesting. Guy uses a CD/DVD disk as a prism to show the spectrum of daylight vs. CFL vs. LED light sources.

I made a spectroscope using a cheap diffraction grating, a cardbox box and a ~50mm projector lens as a collimator:



The grating - dirt cheap on eBay:



You shoot the grating with the lamp shining through the slit (two utility knife blades) at the other end (guess the type of lamp).



The nearest WB to "equal energy" seems appropriate. On my Sigma DSLR these days I remove the hot mirror (easily done with the thumb nail!) to eliminate it's UV/IR blocking effect.

Then convert to TIFF and open in ImageJ to get a response graph.

Here is a comparison between an LED Flood Lamp lab test and the method describe above:





The blue was not as evident in shots as the peak would suggest but, based on the graph, I now use their 3500K model with great success.

Here's a CFL compared to a GE Halogen flood:



Hope this is of interest.

« Last Edit: November 09, 2015, 11:18:21 am by xpatUSA »
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best regards,

Ted

Jim Kasson

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Re: CFL vs. LED vs Daylight spectrum.
« Reply #4 on: November 14, 2015, 11:02:26 am »

Good job, Ted.

Jim

xpatUSA

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Re: CFL vs. LED vs Daylight spectrum.
« Reply #5 on: November 14, 2015, 11:55:14 am »

Good job, Ted.

Thanks Jim, praise indeed!

I was beginning to think that I had posted a thread-stopper ;)
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best regards,

Ted

GrahamBy

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Re: CFL vs. LED vs Daylight spectrum.
« Reply #6 on: December 05, 2015, 02:44:27 pm »

Nice, love it :)
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