J.W. Speaker Denouncing Low-CCT White Light?

[och]

Which is actually a good thing because that means more contrast between the road and road markings, as well as anything on the road.

Ugh, I dont know... Potholes, especially with standing water, are probably harder to see?

 

[cetary35]

Well, I can't find it. There are related papers though:

Which doesn't line up with the chart you "found" on your hard drive. The paper also does not quantify seeing ability or detection distances only using the phrase "apparent brightness". But appearent brightness is not detecting moving objects.

It's called lumen effective multiplier.

Just search for lumen effectiveness multiplier.

Why don't YOU search for it, and you link it for us?

Lumen effective multiplier is simply calculating the eye's response in the mesopic region to a given spectrum, as opposed to in the photopic region where it's usually done.

Resource please, and how it's relevant to the discussion at hand.

I'm simply saying that the lower CCT will need to have a higher intensity to give the same visual response/reaction time as a higher CCT source.

The UMTRI study proves you wrong, as far as car headlights go.

A full study would need to be done. That's obviously way beyond my scope (or yours).

Time for my own argumentum ad nasuim. Do you read? The UMTRI study...

No evidence was observed that target detection is
enhanced with blue headlamps for either peripherally viewed or centrally viewed targets.

 

[jtr1962]

Ugh, I dont know... Potholes, especially with standing water, are probably harder to see?

As a cyclist, I know all about seeing potholes. Under HPS, even the deep ones looked flat until I was almost on top of them. The 4300K LEDs let me see them well in advance. 3000K LEDs are somewhat in between HPS and 4300K LEDs. Standing water in potholes isn't a big issue. I'll see something reflecting off it long before I get near the pothole. In fact, I see water on the roadway surface great with 4300K LEDs. I barely saw it, or not at all, with the old HPS lights.

 

[cetary35]

Which is actually a good thing because that means more contrast between the road and road markings, as well as anything on the road.

Research please. I can see you are very opinionated.

 

[jtr1962]

Time for my own argumentum ad nasuim. Do you read? The UMTRI study...

So you're basing all your argument over one study done over 20 years ago? I've read lots of other studies which came to different conclusions, like these:

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Why has the automotive market moved en masse to ~5000K if lower CCT is better? Wouldn't they face lots of lawsuits if they moved to a product which was less safe?

Research please. I can see you are very opinionated.

This doesn't require a research paper. Look up the definition of contrast. This was in response to "I also find that bluer light gets absorbed more by fresh black asphalt vs yellow halogen light." If more blue light is absorbed by the asphalt you get a darker background, hence more contrast between the road and anything on it. Just applying the definition of contrast.

What you're looking at is very relevant to what type of light is best. For things which tend to be heavy in warmer colors, obviously lower CCT lights will improve contrast. For things which are mostly cool or neutral, higher CCT wins.

 

[och]

As a cyclist, I know all about seeing potholes. Under HPS, even the deep ones looked flat until I was almost on top of them. The 4300K LEDs let me see them well in advance. 3000K LEDs are somewhat in between HPS and 4300K LEDs. Standing water in potholes isn't a big issue. I'll see something reflecting off it long before I get near the pothole. In fact, I see water on the roadway surface great with 4300K LEDs. I barely saw it, or not at all, with the old HPS lights.

HPS lights are not a good comparison, they are generally terrible, make all the colors look the same, cast weird shadows, and aren't as bright as LEDs. They were providing minimal illumination.

I'm not an expert in this by any means, but I drive a variety of cars and motorcycles, and I notice than on very dark asphalt halogen headlights seem to be more effective than HID/LED.

 

[och]

Why has the automotive market moved en masse to ~5000K if lower CCT is better? Wouldn't they face lots of lawsuits if they moved to a product which was less safe?

A lot of it has to do with marketing. Remember in 2000s when HIDs were all the craze, all factory HID systems were 4100k, while a bunch of cheap HID retrofits were 5000K, 6000K, even up to 12,000K in extreme cases.

Also, when bright white LEDs first appeared on the market and were all the rage, they were all cool white. It took several years for warm white LEDs to appear, and there are very limited choices still when it comes to neutral/natural white LEDs at 4100K.

This doesn't require a research paper. Look up the definition of contrast. This was in response to "I also find that bluer light gets absorbed more by fresh black asphalt vs yellow halogen light." If more blue light is absorbed by the asphalt you get a darker background, hence more contrast between the road and anything on it. Just applying the definition of contrast.

Correct, unless it's a dark object on the dark asphalt.

What you're looking at is very relevant to what type of light is best. For things which tend to be heavy in warmer colors, obviously lower CCT lights will improve contrast. For things which are mostly cool or neutral, higher CCT wins.

But this really sums up the whole thread. We're going back and forth over mundane color temperature here, while the color of road surface and the color of objects on the road plays a lot bigger role.

 

[jtr1962]

HPS lights are not a good comparison, they are generally terrible, make all the colors look the same, cast weird shadows, and aren't as bright as LEDs. They were providing minimal illumination.

I'm not an expert in this by any means, but I drive a variety of cars and motorcycles, and I notice than on very dark asphalt halogen headlights seem to be more effective than HID/LED.

The thing is HID/LED often have very different beam patterns, making a true A/B comparison impossible. It could be that the halogen beam pattern reflects back more of what you want to see, and less of what you don't.

 

[JustAnOldFashionedLEDGuy]

Your studies aren't about driving. The only car headlight related study that promoted the use of blue-enriched white light was one done by Sylvania that showed a near insiginificant improvment in seeing ability in the out of focus periphery.

This study done by Nancy Clanton showed the highest CCT LED street lights performing nearly the worst in target detection tests. The visibility tests involved taking people as passengers in a moving car and having them visually identify objects on the road surface. The test speed was 30mph. The 4500K LED performed nearly the worst. The 3500K LED in Test sites 4 & 5 and the 3000K induction at test site 1 performed the best. This study is much more immediately relevant to driving then children sitting in a classroom, and this study is more recent to. It also tests newer lighting technologies out in actual streets. The tested seeing distances, at only 18 inches, of your studies isn't reflective of the seeing distances of driving either.

It is impossible to reach the conclusions you have made with the data available. The only conclusion the researcher really made was more light, better detection. The two induction test runs, and one LED run had the highest minimum levels, and also better uniformity. You could only make a deterministic conclusion with the same fixture with different CCTs/spectrums.

 

[jtr1962]

A lot of it has to do with marketing. Remember in 2000s when HIDs were all the craze, all factory HID systems were 4100k, while a bunch of cheap HID retrofits were 5000K, 6000K, even up to 12,000K in extreme cases.

Those ultra high CCT retrofits are awful things which IMO gave a bad name to HIDs.

Also, when bright white LEDs first appeared on the market and were all the rage, they were all cool white. It took several years for warm white LEDs to appear, and there are very limited choices still when it comes to neutral/natural white LEDs at 4100K.

Believe me, they exist, just maybe not as common in the flashlight world. I can get mid-power LEDs in any color temperature I want from 2200K to 6500K with CRIs of 90 or better. CRI 95 is starting to become semi-common now.

Correct, unless it's a dark object on the dark asphalt.

In which case sometimes you won't see that object regardless of light source.

But this really sums up the whole thread. We're going back and forth over mundane color temperature here, while the color of road surface and the color of objects on the road plays a lot bigger role.

Yes, but it seems the OP is fixated on high CCT lights are evil incarnate, regardless of how they're applied. In cities with their typical cooler/neutral pallet higher CCT streetlighting seems to work better. Out in the country where you might have lots of organic matter maybe 3500K or less might offer a slight advantage. One interesting idea I just thought of might be adjustable CCT headlights. You would need a computer to calculate contrast of a scene, and continually adjust the headlights to maximize that.

One thing I'm puzzled over though is the OP's link to a city that put in LEDs which are virtually indistinguishable from HPS. Almost to a person, everyone will agree HPS is just awful. Why even try to emulate it?

 

[JustAnOldFashionedLEDGuy]

With the research I linked above, higher color temperature lights do not provide any significant improvement in real world driving conditions. However, they do increase glare.

The most critical aspect for driving was none of the qualities listed. Color rendering, even visual acuity is not important. What is important is object detection distance and speed. As well, one must both consider what happens in the central cone, and what happens in the periphery. In the central cone, almost anything works if there is some contrast and enough light. In the peripheral vision, higher CCT (which does not mean high) is better. Further to that, it is not just peripheral, but photopic/mesoptic/scotopic. A comment was made about cycling with 3000K versus higher CCT. This is a relevant item. When driving, we are normally concerned with larger items. When cycling, smaller items are often critical, and shadowing can be significant to drive lighting levels from photopic/mesoptic, into the scotopic. A port hole that may not be a big deal on a car, can be critical on a bicycle and due to low speed, can often be in the peripheral vision.

 

[cetary35]

OP is fixated on high CCT lights are evil incarnate, regardless of how they're applied.

Not relevant to the discussion. High CCT LEDs may have their use cases, but headlights and street lights aren't those.

In cities with their typical cooler/neutral pallet higher CCT streetlighting seems to work better.

Research please.

One thing I'm puzzled over though is the OP's link to a city that put in LEDs which are virtually indistinguishable from HPS. Almost to a person, everyone will agree HPS is just awful. Why even try to emulate it?

No, the link I provided included a poll with public input. Most of the public preferred 2200K over the cooler CCT options. You have your opinion, but that did not line up with Pepperill's.

 

[JustAnOldFashionedLEDGuy]

It has been well documented by the AMA that high color temperature LED street lights worsen glare particularly for older drivers.

Feel free to search this cite for where us (actual lighting experts) pilloried the AMA, their joke of a statement, their lack of qualification of said statement, and the lack of consideration of requirements.

 

[JustAnOldFashionedLEDGuy]

cetary35 said:

Ah, more mis-leading information. Time and time again when 4000K LED and 2200K/2700K/3000K LED is tested in cities, the public consistently prefers the warmer color temperatures. This was shown in Riverside, CA; Davis, CA; Phoenix, AZ, and Pepperill, MA.

---------------------------

What the public prefers is rather meaningless. What prevents injuries is. That they prefer 2200 is really not relevant. Hate to say it, but people often don't know what is good for them.

w.r.t. glare. Glare response is almost exclusively from blue photoreceptors, so whatever stimulates them gets treated the same. How much stimulates them is of course how much light, and how wide the pupil (iris) is. Glare in the peripheral can also annoying. HOWEVER, we are back to what people prefer and what matters. Old people may not like glare, but is it discomfort glare or disability glare. A bit of glare that causes some discomfort, but does not cause disability, may be preferable for acuity and reducing injury/death. Of course, add in some blue, pupil closes, less blue gets in ....

 

[JustAnOldFashionedLEDGuy]

Those ultra high CCT retrofits are awful things which IMO gave a bad name to HIDs.

Believe me, they exist, just maybe not as common in the flashlight world. I can get mid-power LEDs in any color temperature I want from 2200K to 6500K with CRIs of 90 or better. CRI 95 is starting to become semi-common now.

~4000K LEDs are probably the most common LED made as that is by far the most common commercial indoor followed by 3500K. Asia has mainly 5000K commercial indoor and even residential. Really, you can get any CCT in absolutely any volume you want today. 0 restrictions. w.r.t. CRI, it makes little sense to go above 80CRI (or lower), for street lights, and even if you reduce blue, there is no need to worry about CRI. You are better off converting blue to near green and having a low CRI but high lumens. You do want some blue though. CRI is somewhat meaningful for residential and some urban areas for aesthetics. For many areas is is rather meaningless.

 

[JustAnOldFashionedLEDGuy]

I also find that bluer light gets absorbed more by fresh black asphalt vs yellow halogen light.

That is for the most part not true. Angle of light to the surface can come into play though.

 

[jtr1962]

What the public prefers is rather meaningless. What prevents injuries is. That they prefer 2200 is really not relevant. Hate to say it, but people often don't know what is good for them.

Which is pretty much the same thing I've been saying. The purpose of streetlights and head lights is safety. It's not up to an opinion poll. Sure, there are certainly some valid complaints like unnecessary light trespass, or higher intensity than needed for safety. Those are addressed with proper fixture design. But CCT isn't something that should be put to a public poll.

The preference the OP alludes to could simply be an artifact of having lived with HPS outdoors for decades. The public got used to it, so any major change is jarring. People get used to junk food also. It doesn't mean it's good for them.

 

[och]

Those ultra high CCT retrofits are awful things which IMO gave a bad name to HIDs.

Oh there were low CCT retrofits too, lol. I had a set of yellow HIDs swapped into the car I had back then - it originally had yellow fog light housings with halogen bulbs, and with the HID retrofit the light was much brighter and even more yellow. Looked great, at the expense of probably blinding oncoming drivers.

But I'm sure marketing has played a big role why most automakers went from 4100-4300K to 5000K headlamps.

Believe me, they exist, just maybe not as common in the flashlight world. I can get mid-power LEDs in any color temperature I want from 2200K to 6500K with CRIs of 90 or better. CRI 95 is starting to become semi-common now.

Yes, I was able to find them for required applications as well, they are just not as widely available. When it comes to flashlights in particular, there are almost none available - but I do have a couple of Xeno flashlights that I bought years back with neutral white XML.

In which case sometimes you won't see that object regardless of light source.

Yes, but it seems the OP is fixated on high CCT lights are evil incarnate, regardless of how they're applied. In cities with their typical cooler/neutral pallet higher CCT streetlighting seems to work better. Out in the country where you might have lots of organic matter maybe 3500K or less might offer a slight advantage. One interesting idea I just thought of might be adjustable CCT headlights. You would need a computer to calculate contrast of a scene, and continually adjust the headlights to maximize that.

One thing I'm puzzled over though is the OP's link to a city that put in LEDs which are virtually indistinguishable from HPS. Almost to a person, everyone will agree HPS is just awful. Why even try to emulate it?

To say that warm white LEDs emulate HPS is disingenuous. HPS has a very narrow spectrum, its probably the worst quality light except for LPS, even worse than MV. With LEDs, there are plenty of scenarios where one color temp can have a legit advantage over the other.

I don't want to speak for the OP, but I think he is simply upset about JW Speaker giving into the modern blue headlight trend. But they almost have no choice but to, if you look at the photo of my motorcycle, the much superior JW Speaker headlight looks almost yellow compared to the cheap passing lights, and most clueless consumers will probably perceive the bluer lamps to be superior - much like they were during the HID retrofit craze.

 

[jtr1962]

~4000K LEDs are probably the most common LED made as that is by far the most common commercial indoor followed by 3500K. Asia has mainly 5000K commercial indoor and even residential. Really, you can get any CCT in absolutely any volume you want today. 0 restrictions. w.r.t. CCT, it makes little sense to go above 80CCT (or lower), for street lights, and even if you reduce blue, there is no need to worry about CCT. You are better off converting blue to near green and having a low CCT but high lumens. You do want some blue though. CCT is somewhat meaningful for residential and some urban areas for aesthetics. For many areas is is rather meaningless.

Don't you mean CRI, not CCT? In many urban areas, since the streetlights are also lighting the sidewalks and businesses, high CRI might be desirable as you said. On an open highway in the middle of nowhere, probably not.

To me 5000K always made sense as its closest to sunlight. Many CCT preferences are cultural though.

 

[JustAnOldFashionedLEDGuy]

These are the relative spectrums in the UMTRI study. To assign any relevance between this study and what would occur with vastly different LED spectrums which may be tailored either indicates total lack of understanding of this topic, or not having read this in enough detail to realize the conclusions being made in this thread w.r.t. the UMTRI study are deeply flawed.