p1d-ce color rendition: does it affect brightness?
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jtr1962
Flashaholic
I've read that for any given intensity and color temperature a source with a higher color rendering index will appear brighter to the eye even though they measure the same on a light meter. And to complicate things further, if two light sources have equal intensity and color rendition but different color temperatures the one with the higher color temperature will appear brighter to the eye. As for color rendition of the P1D-CE, the Cree is no worse than any other white LED for color rendering. I don't know what bin Fenix is using, but the WH bin I have samples of renders colors quite well, about as good as a triphosphor fluorescent (CRI 85 or 86).
Wiz
Newly Enlightened
I have two P1D Crees and one has a warmer light than the other. The warmer light shows up as producing about 5% less light according to my home built "lumen" meter, and my light meter shows the same. It might be just down to variations in manufacture tolerances, but I think it's a very interesting question.
winny
Flashlight Enthusiast
jtr1962 said:
Wrong.
jtr1962 said:
Not true. When you push the peak beyond the 555 nm line, it appears dimmer.
(Well, it would depend on what your spectrum look like, but to sum up, it's highly likely that the turnover will come close to 555 nm.)
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Wiz
Newly Enlightened
winny said:
Both wrong, it would depend entirely upon the subject that was being illuminated. i.e. green light will appear brighter on objects that reflect green light and absorb other colours, such as tree foliage.
winny
Flashlight Enthusiast
Wiz,
The question was not if you illuminated anything.
The question was not if you illuminated anything.
jtr1962
Flashaholic
I should have been clearer-up to about 6500K to 7000K higher color temperature sources of the same measured brightness appear brighter to the eye. Above about 7000K they start appearing dimmer. This was readily apparent in a local store where some daylight 6500K tubes were side-by-side with 3000K and 4100K ones. These were all T8s with around 2800 design lumens. The 4100K appeared somewhat brighter than the 3000K but the 6500K appeared way brighter than both.winny said:
About the higher apparent brightness of higher CRI sources I read that a while back but I can't remember where. I'm reasonably sure it's true-just try comparing an SP (CRI of 75 to 78) and and SPX (CRI of 85 to 86) tube of the same color temperature side by side. The SPX tube will appear a little brighter even if both measure exactly the same on a light meter. Not as dramatic a difference as sources of different color temperatures, but noticeable.
winny
Flashlight Enthusiast
jtr1962,
Color temperature: Yes, that's true indeed! Just as long as anyone doesn't think 10000 K is more efficient than 4000 K, I'm happy.
CRI: That has very litttle to do with the CRI and much to do with the fact that tri-phosphorous tubes are far more efficient than single-phosphorous tubes. Another benefit is that tri-phosphorous have a higher CRI-value, but don't be tempted to draw the conclusion that high CRI = high efficiency. The most efficient light source for daylight adapted eyes is still monochromatic 555 nm light, which have an CRI-value of zero.
Color temperature: Yes, that's true indeed! Just as long as anyone doesn't think 10000 K is more efficient than 4000 K, I'm happy.
CRI: That has very litttle to do with the CRI and much to do with the fact that tri-phosphorous tubes are far more efficient than single-phosphorous tubes. Another benefit is that tri-phosphorous have a higher CRI-value, but don't be tempted to draw the conclusion that high CRI = high efficiency. The most efficient light source for daylight adapted eyes is still monochromatic 555 nm light, which have an CRI-value of zero.
This is amazing, you all have been insightful! I still don't understand though, is bluish white more efficient and warm white or is it the other way around?
I know I read somewhere the bluish white will tend to be more brighter to the eye, not sure if it's truely brighter?
I know I read somewhere the bluish white will tend to be more brighter to the eye, not sure if it's truely brighter?
winny
Flashlight Enthusiast
timcodes,
Well, it depends on what you mean by blueish white. Aften extensive LED usage, peoples references normally shift.
I don't have the exact figure, but I will try to look it up what the most efficient CCT is, but I expect it to be somewhere between 4000 K and 5000 K (which is bluish white in my eyes), depending on what your spectrum look like. For Philips 35W HE florescent tubes, it looks like this:
CCT [K] flux [lumen]
2700 3300
3000 3300
3500 3300
4000 3300
6500 3100
so you can't really tell. I'll try to do some research what peaks for blackbody radiators.
Well, it depends on what you mean by blueish white. Aften extensive LED usage, peoples references normally shift.
I don't have the exact figure, but I will try to look it up what the most efficient CCT is, but I expect it to be somewhere between 4000 K and 5000 K (which is bluish white in my eyes), depending on what your spectrum look like. For Philips 35W HE florescent tubes, it looks like this:
CCT [K] flux [lumen]
2700 3300
3000 3300
3500 3300
4000 3300
6500 3100
so you can't really tell. I'll try to do some research what peaks for blackbody radiators.
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Wiz
Newly Enlightened
winny said:
What is the point of a flashlight if you are not illuminating anything? Surely that is the only relevant aspect of whether or not a flashlight is brighter.
Wiz said:
I think the point is if you are going to use illumination as the point of reference you would have to be specific as to what you are illuminating, as everything would reflect differently. So it would tend to be more standard and easier to not have another variable in the equation. so generally we would speak of just the light emitted not the light reflected off of something.
Wiz
Newly Enlightened
billhess said:
But the question was which is the brightest tint, not which tint makes a light meter register the highest with the same amount of power consumption etc.
In that case surely a real world test (i.e. trying to identical lights models with different tints side by side in normal use) is as good a test as any to answer the question. After all, the tint that illuminates objects the best and reveals the most detail, is surely the best, regardless of what a meter reads.
Wiz
Newly Enlightened
timcodes said:
For number 2, I expect that it depends on the light meter and they will vary no doubt, but mine seems more sensitive to cooler colours.
I believe that the answer to one and three is the same; it would very much depend on the subject. Let me give you an extreme example: Objects appear the colour they do because they absorb all colours except the one that they appear as. i.e. leaves absorb all light except green which they reflect so they appear green. When night hunting, I use a red filter on my lamp (as do all hunters) because you can have a bright light that throws a long way, but it appears quite dim, because hits the greenery and gets sucked in. When it hits your quarry's eyes however, it's like someone is shining a light back at you. Even other colours like browns and greys appear much brighter in red light than green objects do.
So, if you are in a forest, green light will seem much brighter than red light. In a room that has been decorated in red, a red light will seem much brighter then green. It's worth knowing and taking into consideration when you go outside to do your real world tests.
Wiz said:
Are you kidding. Which is the brightest tint is asking which one puts out the most light(a light meter) not which one reflects the most. What a joke stop trying to play with words to be right. A light meter is a real world test. To say a question like this was meant to really ask which tint would reflect the most in every different kind of surface on the earth is ridiculous.
