Colour Rendition, At what point...

I own both incandescent and LED flashlights and I was wondering something on the way into University this morning. We all know that, at a specific lumen output, the incandescent light will give superior depth and colour rendition.:huh:

However, let us look at an extreme case. Let us take a Minimag with fresh cells (~15 bulb lumens on a good day) and a Fenix P1D-CE Q5 (~170-180 emitter lumens). Eyeballing the output, colour rendition is definately superior with the LED-based flashlight, purely due to the 'brute-force' high-lumen approach.:thumbsup:

So my question is...

"At what point does the higher lumen output of an LED compensate for the inherent colour-rendition deficeit?" :shrug:

Unfortunately, the lumen-gaps are too large between my incandescent/LED flashlights to conduct an experiment myself. From what I have read, some CPF folk would claim that a 150 lumen LED flashlight should have equal colour rendition to a 50 lumen incandescent, which means the cut-off point is at a ratio of 3x.

Of course, there are them that argue that an LED can NEVER match the rendition of glowing tungsten. Please consider though my extreme case example.

Thanks for your thoughts,

Mike

Just a side note, we had a foggy morning here in Manchester. My P1D-CE Q5 does not cut through fog as well as my Mag 2D ROP, but it is certainly a vast improvement over 5mm LEDs, and earlier Luxeons.

Colour rendition is interesting. LED's have a spectrum that is low in the middle of visible light so do not have, no matter how bright, the rendition of an incandescent.
However, the perceived colour of an LED can make colour identification quite good.
What luxeon lights were less than 40-50 lumens, everybody had their favourite bin and colour; now that 100+ lumens are common, slight variations in colour are easily tolerated by most.
To answer your question directly--"it depends" :devil:
Greg

indoors they are about equal, I'd take a 100 lumen LED or a 100 lumen incan and be happy.

outdoors on a good day, I'd say you need about 50% more lumens on an LED to work as well on natural subjects, (browns, dark earthy colors, greens, etc). So a brand spankin new Q5 250 emitter lumen LED light will perform at least as well as a ~175 lumen incandescent. But I have seen plenty of evidence that with so much effort on maximizing the throw of the cree, we have crees available now that trounce all over their similar sized incandescent cousins even in the throw department... The MRV, Tiablo, and Deree stuff is blowing stuff like the TL-3 away, which used to be the king of throwers in that size class.

In fog, rain, or snow, I'd say you need a little more LED lumens to compensate, perhaps somewhere around double.

I really don't think a 50 lumen incan is going to "outperform" a 150 lumen LED in any circumstance, at that point it is well beyond scientific reasoning or logic, it's on to the region of personal preference, which in the case of flashlights, is completely fine. (there is no wrong in dealing with preferences, only more flashlight to explore)


My thoughts on where the breaking point is really based on the idea that the lights being compared have the same beam profile, the reality is that if you have the right focus for the job, any source can be excellent. For example if you were to compare a super-thrower cree, to something like a Surefire P91 lamp driven on a pair of 18650s. The P91 will totally annihilate the cree with about double the total lumen output, and more ideal color spectrum for outdoors, but it's a total flood monster, and the cree would undoubtedly outperform it at certain functions, like spotting an address off in the distance..


The other interesting thing worth noting.. Lets say you have 2 lights side by side, both 2x18650 powered. One is a Cree driven at 1 amp and has a runtime of 4 hours or more and is rated 200 torch lumens. The other is a equally bright incandescent, something like a HO-9 lamp (about 12W), runtime is about 80 minutes..... which one is going to render better after an hour and a half?

GregWormald said:

Colour rendition is interesting. LED's have a spectrum that is low in the middle of visible light so do not have, no matter how bright, the rendition of an incandescent.[..]

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Sorry if I say it so harsh, don't take it personal, but this is BS.

White LEDs are a blue LED with a dye on top. They have a narrow-bandwidth blue emission at ~440-470 nm or so. This light is converted in a continuous, white, spectrum by the dye. This continuous spectrum is, in most cases, a beautiful, perfect, near Gaussian distribution across the visible spectrum (400-700 nm) with a maximum near smack-dab in the middle at 550 nm, or higher for lower color-temp.

The low intensity is not in the middle of the visible spectrum (the local minimum is below 500nm, already quite far towards blue). Good color rendition sources SHOULD go down in this wavelength.

elgarak said:

Sorry if I say it so harsh, don't take it personal, but this is BS.

White LEDs are a blue LED with a dye on top. They have a narrow-bandwidth blue emission at ~440-470 nm or so. This light is converted in a continuous, white, spectrum by the dye. This continuous spectrum is, in most cases, a beautiful, perfect, near Gaussian distribution across the visible spectrum (400-700 nm) with a maximum near smack-dab in the middle at 550 nm, or higher for lower color-temp.

The low intensity is not in the middle of the visible spectrum (the local minimum is below 500nm, already quite far towards blue). Good color rendition sources SHOULD go down in this wavelength.

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Maybe on paper this is all true. But speaking from experience, white LEDs do not give the color rendition that incans do. This is why I use an incan exam light as an EMT - white LEDs do not realistically or clearly render tissue and fluid colors. I've tried several, most recently a Streamlight Stylus. I do have a Peak Fujiyama with a "snow" white LED on order - we'll see how Peaks' famous pure white LEDs do! However, my McKinley with it's 7 white LEDs don't do all that well either, so I'm not expecting much.

I don't know why this is. I accept your statement that the LED emits a nice spectral distribution of light, but something about it is just not right.

I'd really like to see a spectrum of both a good incan and a good white LED - not necessarily a chart, but a spectrum from a prism or diffraction grating. I still suspect there are emission gaps in the LED spectrum.

when I'm in the woods (hiking or biking), I have to be able to see
rocks, ground, sand, grass, trees, brush, maybe some flowers, other ppl, my equipment and wayfinding marks in white, yellow, green, red, blue and brown.

As I own quite some lights and like to have a special size with me, I can often compare between SF 9N, 8X, 6P, Streamlight Scorpion, Scorpion 18650, some cheaper DX hotwires of this output class (2 * CR123), ...
and find myself liking the SF 6P modded with a Cree P4, running at 1 A max the most.
It kicks any of the lights mentionned out of the woods, except for the 9N, but runs longer and seems brighter (white light! The 9N batt seems already dead in comparison)

I've found the color rention of my MTE rebel (0100 bin) to be supurb. Makes my UF cree look like crap and simply embarasses my 3D MagLED to the point I want to drop the Mag-Num star back in!

Or maybe some type of Mag85 or ROP type of mod to the 3D setup.... hmm.... Then again, its just a car light for oh poop on the highway or spotting addresses, so it has a lot of downtime and rechargables would not be ideal.

Indeed, I have opened up a very subjective can of worms. They are all very interesting points of view. Keep them coming.

MikeSalt said:

Indeed, I have opened up a very subjective can of worms. They are all very interesting points of view. Keep them coming.

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That's is quite true - I suspect that my 50 year old eyes are more subject to having problems with odd lighting that some 20 year olds! I hope Peaks' LED does the job though!

Buck91 said:

I've found the color rention of my MTE rebel (0100 bin) to be supurb. Makes my UF cree look like crap and simply embarasses my 3D MagLED to the point I want to drop the Mag-Num star back in!

Or maybe some type of Mag85 or ROP type of mod to the 3D setup.... hmm.... Then again, its just a car light for oh poop on the highway or spotting addresses, so it has a lot of downtime and rechargables would not be ideal.

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Check out the TerraLux U-bin SSC dropin (the *EXB one). The color is the purest white I have seen (I own a bunch of Cree/SSC/Rebel lights, including several Fenix and many cheap DX/KD) and it's a great way to revive a Mag.