A Question on CRI

[TNBaer]

I'm currently designing some outdoor softball field lighting for a municipality. I'm using DHID from Accendo Electronics. Accendo pairs their ballasts with lamps from EYE, Venture, or Sylvania. In the 575 Watt lamp size Venture makes a lamp with 90+ CRI. However, the 575 watt lamp just doesn't have the punch needed for this lighting design. In order to get the sheer amount of lumens I need to use a 750 or 1,000 watt lamp. In doing so my CRI drops to below 70. I love high CRIs (even though the rest of world barely notices), especially in an outdoor sports application where uniform colors are important.

It's my understanding that the reason why is the color rendering is poor is because the higher wattage lamps lack the color spectrum to render specific colors. So it would seem that if I add merely one lamp of a high CRI the spectrum would become available and colors would render well.

Of course, that seems to run counter to common sense. If I have eight poor rendering lamps and one lamp of less light output but good CRI, I'd think I'd still get a bad CRI.

So which is it, can one lamp provide the necessary spectrum or not?

 

[PetrosA]

Will these games be televised? If so, you'll want to check the lighting guidelines for parks and stadiums with broadcast lighting installed (minumum footcandles at field level, lamp types etc.) As far as I remember, stadiums don't necessarily need a certain CRI for cameras since the white balance can take care of a lot of it and many colors are lost in the RGB gamut of the cameras anyway, but I think most have MH installed. If you're not gearing this for television cameras, I guess you could mix the lights, but I'm not sure what the effect will be. I think my first call would be to the manufacturer to ask whether they can offer any advice.

 

[G._S._Ohm]

Try

http://www.fullspectrumsolutions.com/cri_explained.htm


http://www.lowel.com/edu/color_temperature_and_rendering_demystified.html

but it still may come down to mat'l cost + labor cost vs. perceived customer satisfaction.
Plotting price vs. performance you may find a breakpoint that makes this decision for you.

BTW, 10% of the males are red-green colorblind so you only have to keep 90% of the males (and 99% of the females) happy.

 

[G._S._Ohm]

If I have eight poor rendering lamps and one lamp of less light output but good CRI, I'd think I'd still get a bad CRI.

So which is it, can one lamp provide the necessary spectrum or not?

You'd have the power of eight spectrums adding in some way that give poor color, and one weak spectrum that gives good color.
Sounds like bad CRI, almost independent of the frequency response of the human eye.

Try it: get a fluorescent and an incandescent and vary their distances from a multicolor subject to give an 8:1 intensity ratio and get a female or several people (a jury) to say what it looks like. Try one source, then the other, then both.

 

[Electric-Light]

I'm currently designing some outdoor softball field lighting for a municipality. I'm using DHID from Accendo Electronics. Accendo pairs their ballasts with lamps from EYE, Venture, or Sylvania. In the 575 Watt lamp size Venture makes a lamp with 90+ CRI. However, the 575 watt lamp just doesn't have the punch needed for this lighting design. In order to get the sheer amount of lumens I need to use a 750 or 1,000 watt lamp. In doing so my CRI drops to below 70. I love high CRIs (even though the rest of world barely notices), especially in an outdoor sports application where uniform colors are important.

It's my understanding that the reason why is the color rendering is poor is because the higher wattage lamps lack the color spectrum to render specific colors. So it would seem that if I add merely one lamp of a high CRI the spectrum would become available and colors would render well.

Of course, that seems to run counter to common sense. If I have eight poor rendering lamps and one lamp of less light output but good CRI, I'd think I'd still get a bad CRI.

So which is it, can one lamp provide the necessary spectrum or not?

CRI has little to do with aesthetically pleasing anyways and its only for comparing similar CCT lamps There are two types of CRI, but unless specifically noted, the one we use is Ra8, which is the average rendition percent of eight color samples. Another system is called Ra14. Ra8 ignores R9 to R14. Of those, R9 is of deep red. The typically presented Ra8 or "CRI" completely hides R9 rendering ability anyways (flesh, blood, red meat, tomatoes, etc)

RE850 have an Ra8 of 86 while Chroma 50 is only 90, but the latter has R9 value of something two figures while R9 on RE80 is about zero. The RE850 accentuates some colors and make them look vivid while the latter tend to look more "flatter".

The Reveal light bulb is something like 70 CRI while regular incandescent is 100. The idea of Reveal is to raise contrast by "hiding" some and "accentuating" the rest for psychologically pleasing appearance (subjective speaking..).

 

[Electric-Light]

And yes you can supplement the spectrum with additional sources. An example of this is the Philips L Prize LED lamp which raises the R9 to >50 which is the requirement for the L prize. It uses blue LEDs to excite phosphor blend in the shell and red LEDs to blend into the light to supplement R9 component.

 

[weressl]

I'm currently designing some outdoor softball field lighting for a municipality. I'm using DHID from Accendo Electronics. Accendo pairs their ballasts with lamps from EYE, Venture, or Sylvania. In the 575 Watt lamp size Venture makes a lamp with 90+ CRI. However, the 575 watt lamp just doesn't have the punch needed for this lighting design. In order to get the sheer amount of lumens I need to use a 750 or 1,000 watt lamp. In doing so my CRI drops to below 70. I love high CRIs (even though the rest of world barely notices), especially in an outdoor sports application where uniform colors are important.

It's my understanding that the reason why is the color rendering is poor is because the higher wattage lamps lack the color spectrum to render specific colors. So it would seem that if I add merely one lamp of a high CRI the spectrum would become available and colors would render well.

Of course, that seems to run counter to common sense. If I have eight poor rendering lamps and one lamp of less light output but good CRI, I'd think I'd still get a bad CRI.

So which is it, can one lamp provide the necessary spectrum or not?

Lighting design rule number 2 or 3; do not, under any cirumstances, mix different wattages or types of lights. When purchasing MH lamps, read carefuly the manufacturers claim, or lack thereof, the color or CRI uniformity and stability of production batches. Always group relamp.

 

[steve066]

Of course, that seems to run counter to common sense. If I have eight poor rendering lamps and one lamp of less light output but good CRI, I'd think I'd still get a bad CRI.

So which is it, can one lamp provide the necessary spectrum or not?

Adding one lamp with a high CRI won't provide enough lumens in the frequencies that the other lamps are lacking. The overall lighting levels and color rendering will still be largely determined by the other lights.

So if most people don't notice good or bad color rendering in the first place, they sure won't notice the difference that one lower wattage high CRI fixture makes.

 

[Derek Hou]

So,what's your final decision?Have you found a proper way to balance the lumens and CRI?

Actually,our induction lamp face the same dilemma,we have to make the decision for the customers who donnot pay mauch attention to the differences.CRI above 80 is our regular data.