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

cetary35

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A lot of what you are saying JTR is correct
No, @jtr1962 is going back and forth on his position. First he argues that higher CCT provides better visual acuity providing a study using fluorescents and another study on HPS and MH. And using those studies he tries to argue for high CCT LED. He then supports a position that studies like that aren't relevant by supporting your comment on SPD and the UMTRI study.
 
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kerneldrop

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My city can't afford street lights.

I don't rely on governmental lighting.
My truck has 3 light bars, 2 forward facing KC lights, 2 rearward facing KC lights, and purple and green undercarriage lights.
Even my wheels have their own LED lights.
I have them hard wired with the ignition.
Send lumens are stay on the porch

'Merica
 

alpg88

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Problem is your management probably hired whatever electrician they normally use, he recommended some cheap lights he makes good margin on, used some stupid 2:1 "rule of thumb" to convert from HPS watts to LED watts, and well now you have a crap lighting system. When the original fixtures were put in for your parking lot, it is almost a given that an engineer or lighting designer did a proper analysis and picked specific fixtures, pole heights, and worked with pole spacing limitations to create a compliant lighting setup.
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I take that all back if you used to have side of wall wallpacks. They are a pain in the rear when replacing. Many jurisdictions have lighting ordinances and those old wall packs are no compliant. When you replace them, you are supposed to use full cut-off enclosures (no uplight). That again takes someone who knows what they are doing to select a proper fixture.
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Of course, I also see idiots put up wickedly bright LED fixtures, generally cheap off-shore imports, and mount them on swivel mounts and have them 30+ degrees of horizontal and the end up lighting up the neighborhood. I am currently in the process of giving someone an education about that. I suspect they are going to have to rip out $20,000 of lighting. I don't feel a bit bad though, they cut corners, and their residential neighbors are being punished for it.
That is exactly what happened, they also cut up perfectly good poles and installed crappy ones that are not as long,. Pure corruption and greasing hands. there is no other explanation.
 

JustAnOldFashionedLEDGuy

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To quote Alaric,

RP8 standards for street lighting all define lighting levels that fall by a large majority into the mesoptic range for the intended target areas, i.e. the street, and sidewalks, however, keep in mind, these averages may be as low for low pedestrian conflict local roads as 0.3 cd/m^2 with a 6:1 min/max which means getting to 0.05 real world, from target sources. Scotopic is 0.01, so you don't have to be far off the target areas to get to 0.01 especially when the goal of modern lighting is limited light trespass. On the other hand, for highways, the minimum can be as high as 1 cd/m^2, with a 3:1, which means we are pushing over 3, hence into photopic. When discussing headlights, we are photopic in close to the vehicle, stretching out to the periphery in mesoptic primarily, with some scotopic at the edges. However, whether mesoptic or scotopic, it is really meaningless as rods are active in either case and they have a different sensitivity spectrum, and as you reduce light levels, even though not technically scotopic, by definition, they are more dominant, and as you move away from the center of our vision, their relative density also increases. In fact, from an evolutionary biology standpoint, in many ways they have exactly developed to detect a poorly defined blob moving in our periphery under moon light.

In terms of blue light, no, at light, when our pupils are wide, blue light does not focus as well and does not give us high visual acuity. It does not need to. We don't have much visual acuity in our periphery anyway. It really is mainly about object detection in the periphery that we then scan our central vision towards to identify.
 

cetary35

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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.
The well researched experts like @Alaric Darconville and @-Virgil- sound quite open towards lower blue light and possibly street lights as well.
 

cetary35

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RP8 standards for street lighting all define lighting levels that fall by a large majority into the mesoptic range for the intended target areas, i.e. the street, and sidewalks, however, keep in mind, these averages may be as low for low pedestrian conflict local roads as 0.3 cd/m^2 with a 6:1 min/max which means getting to 0.05 real world, from target sources. Scotopic is 0.01, so you don't have to be far off the target areas to get to 0.01 especially when the goal of modern lighting is limited light trespass. On the other hand, for highways, the minimum can be as high as 1 cd/m^2, with a 3:1, which means we are pushing over 3, hence into photopic.
Continuously lighting highways is a poor/questionable practice, btw.
Previously the Nord-pas-de-Calais in 2007 region switched off lighting on the A16 route to Belgium but the state and local authority have yet to decide how to split the savings.

According to road monitors the DIRIF, the number of accidents dropped by 30% as a result of the change.

"Cars go slower and the drivers are more aware," said a spokesman for the DIRIF.
And Caltrans' experience with ridding themselves of continous expressway lighting.
In the 1970s, in response to an energy crisis, CalTrans decided to remove all roadway lighting from limited access freeways, except for those located at the interchange. In the 30 years since these roadway lights were taken down, CalTrans has not seen the need to reinstall roadway lighting on freeways. CalTrans has now commissioned a study, due for completion in 2008, to determine whether roadway lighting is necessary even at interchanges.
 
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desert.snake

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That's all well and good, but it seems to me that it's better to move away from human vision and use infrared machine vision. In the event that the night vision device fails, the gearbox is blocked at a maximum speed of 20 km / h

Something like this
 

JustAnOldFashionedLEDGuy

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Guess what? UMTRI conducted another study with LED! Here are their findings.

Ultimately, the same properties are at play. The more blue a light source has, the more glare it will produce. Even though that chart showed a spectrum normalized for a black body, it still is relevant. The chart you linked also illustrates that even providing perfect CRI and SPD while increasing CCT will still increase glare.

NO ONE DISPUTES THIS. And this is NOT the conclusions you jumped to from the last study that were not actually in that study.

To a point, increasing CRI, assuming a black body or even traditional LED spectrum will reduce discomfort glare because it reduces the blue LED pump peak at 440-450nm, which is where the blue cones are most sensitive. That is one specific glare response to a rapid light level change in the blue rods. The IPRGC are also create a "bright light" response and are slower. Think continuous oncoming bright headlights. That happens predominantly up to 525 nm and overlaps rod response which adds complexity to the considerations.
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We can tailor light sources to reduce deepish blue (the pump color), while still providing significant rod response, and by virtue of how CCT is calculated, it will still have a relatively high CCT, but will not produce as much discomfort glare response from blue cone stimulus, but will be perceived as bright due to IPRGC stimulus. The issue, though, is available phosphors. Phosphors to accomplish this are relatively new, and at this point, wider than preferred, though the result is still better than the blue pump.
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Throwing out random papers and isolated facts without understanding their full meaning and implications is doing little to move the conversation forward.
 

JustAnOldFashionedLEDGuy

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But hey, @jtr1962, now that we're throwing out any study since it wasn't done with LEDs, I assume we're also going to be throwing out the two studies you linked in the beginning with high CCT fluorescents?

We threw out the study because you made a conclusion that was not at all supported by the data in the study. However, there have been specific studies done, even pre-LED, that looked at the relationship of rod / cone stimulation as the tested stimulus, and evaluated at specific lighting levels (which by definition are photopic), and measured object detection speed. That information has transportable relevancy no matter the light source.
 

alpg88

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That's all well and good, but it seems to me that it's better to move away from human vision and use infrared machine vision. In the event that the night vision device fails, the gearbox is blocked at a maximum speed of 20 km / h

Something like this

This has been on a market for close to 10 years, it is around 5k to buy, we have installed few of those in our shop, great unit, but it has one major flaw, there is a delay, so it is only good as auxiliary unit, it is fine to spot a deer 100 or so yards ahead, but if it jumps 10 feet in front of you, you'll hit it before you'll see it.
 

JustAnOldFashionedLEDGuy

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That's all well and good, but it seems to me that it's better to move away from human vision and use infrared machine vision. In the event that the night vision device fails, the gearbox is blocked at a maximum speed of 20 km / h

Something like this


See my post above where I said shortly it will be all moot because cars will be self driving and use non-visible wavelengths and LIDAR :)
 

cetary35

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And this is NOT the conclusions you jumped to from the last study that were not actually in that study.
What are you talking about? Both UMTRI studies showed more blue light producing more glare.
We can tailor light sources to reduce deepish blue (the pump color), while still providing significant rod response, and by virtue of how CCT is calculated, it will still have a relatively high CCT, but will not produce as much discomfort glare response from blue cone stimulus, but will be perceived as bright due to IPRGC stimulus.
Guess what you can also do? You can also cut down CCT while further cutting down blue. Any sort of improvements of cutting down the blue spike could be applied to lower CCT products to bring their blue light content even lower, e.g. the voilet pump Sunlike.

Throwing out random papers and isolated facts without understanding their full meaning and implications is doing little to move the conversation forward.
Making claims without any links to peer reviewed studies, like what your commentary has been, doesn't move the conversation forward.
 

JustAnOldFashionedLEDGuy

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No, @jtr1962 is going back and forth on his position. First he argues that higher CCT provides better visual acuity providing a study using fluorescents and another study on HPS and MH. And using those studies he tries to argue for high CCT LED. He then supports a position that studies like that aren't relevant by supporting your comment on SPD and the UMTRI study.

I don't perceive he has at all. However, I do see you putting out papers and drawing conclusions that are either not supported by the data in the paper and/or are irrelevant to the discussion. JTR may be lacking the experience and knowledge to understand the subtleties of what he is perceiving and what the papers reveal versus how that can be more effectively implemented in the real world to achieve more goals.
 

cetary35

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I don't perceive he has at all. However, I do see you putting out papers and drawing conclusions that are either not supported by the data in the paper and/or are irrelevant to the discussion.
This comment right here.


1664890617946.png

You argue that studies that don't use an LED's spectral power aren't relevant here. @jtr1962's commentary specifically quoted the use of fluoresecnt lights, a light source with an SPD totally different from LED and therfore not relevant to the topic according to your logic. So, then what is it @jtr1962? The studies that you linked are not relevant here? Or are they relevant as long as it supports your feelings? Sure looks like going back and forth on your stance.
1664890942764.png
 

JustAnOldFashionedLEDGuy

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What are you talking about? Both UMTRI studies showed more blue light producing more glare.

Guess what you can also do? You can also cut down CCT while further cutting down blue. Any sort of improvements of cutting down the blue spike could be applied to lower CCT products to bring their blue light content even lower, e.g. the voilet pump Sunlike.


Making claims without any links to peer reviewed studies, like what your commentary has been, doesn't move the conversation forward.

Feel free to get an education, and a few years of experience, and then you will be able to find and research the papers that validate everything I say and actually understand what I am saying. Till then, I have wasted enough time on you.
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Violet pumped LEDs were going to be the next great thing! The inventor of the blue-LED said so in 2015. Unfortunately, we need to deal with the reality of today. Several things happened/didn't happen. Blue LED WPE continued to get better than the 50-60% in 2015 and can almost reach the efficiencies of GaN on Gan purple. The currently available phosphors achieve much much better QE with the blue pump. Blue LED die has become almost free.
 

cetary35

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I do see you putting out papers and drawing conclusions that are either not supported by the data in the paper and/or are irrelevant to the discussion.
I have consistently followed and carefully quoted the results of the linked studies. You haven't provided anything other then commentary.
 

cetary35

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Feel free to get an education, and a few years of experience, and then you will be able to find and research the papers that validate everything I say and actually understand what I am saying. Till then, I have wasted enough time on you.
Yes, I'm sure I too will rise to the standard of random internet person making un-researched/un-verifiraible claims on the internet.
 
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