Tint & Lumens ??

[Robocop]

I almost purchased a few left over Inova X1 lights at Target as they were marked down to 13 dollars however the tint stopped me from doing so. I tried at least 4 samples and all were a very brownish creamy tint and when compared to my keychain LOP it really made the X1 look dim and brown in tint.

When it comes to actual Lux readings or output figures does the luxeon tint have any effect on the numbers? I was curious when I got home and compared several lights. I have one Orb Raw that is I believe an XO tint and looks to be a crystal white almost bluish tint. When this light is compared to other brownish or creamy yellow tinted lights the Orb always looks brighter....even if a ceiling bounce test says otherwise. I have lights I know are higher in output but again lower output more whiter tinted lights always seem to "look" brighter and I wonder if a light meter could also be fooled like my eyes?? So can anyone say if a very bright tinted lower power light will show a higher lumen figure than a more powerful browner tinted light??

 

[Gunner12]

I think some Lux meters will be affected by tint.

 

[ZMZ67]

Looking at the specs Lumileds gives on thier website it seems like the cool whites are capable of producing the most light followed by neutral white then warm white.The cool white lights always appear brighter to me as well.I have a couple of Tiablo A1s,one is very warm and the other cool white.The cool white one seems significantly brighter than the warm white one.

 

[LukeA]

Tint has an effect on human perception of brightness.

Brighter emitters are typically cooler because of characteristics of the phosphor and its deposition. Irrespective of differences in die, a heavier coat of phosphor will result in a warmer tint, but will also block more light than less phosphor.

I do not know if light meters are affected by tint, but I have a very difficult time believing that that's not total BS.

 

[MrGman]

the integration sphere and meter that measure lumens doesn't care about color. It will measure total light energy. Meaning if its 16 lumens of green its 16 lumens. If its 16 lumens of red its 16 lumens. Your eyes will think the green is brighter than the red because of the difference of receptors in your eye ball, but if they were both 16 lumens to start the meter would read it correctly.

Whatever the total light output is of a LED light source, the tint doesn't change the reading to the meter. Our biased brains based on our non linear eyeballs make us believe otherwise.

"Brighter emitters are typically cooler because of characteristics of the phosphor and its deposition. Irrespective of differences in die, a heavier coat of phosphor will result in a warmer tint, but will also block more light than less phosphor."

The LED raw output is actually blue and the only "white" light you see comes from the phosphor glowing from the blue energy its receiving. Its mostly a yellow light output that combined with the blue gives the perception of white. That doesn't mean that there isn't more to the spectrum, but its "mostly" yellow". If the Phosphor wasn't absorbing most of the blue light from the LED you would just have a cheesy looking blue light output. So for the most part the phosphor isn't "blocking the light" its creating most of the "white" light that you see. But of course if they put it on too thick it would get dimmer as the blue light wouldn't make it to excite the phosphor at the front as much. Its a delicate balance but the phosphor is making the light that we see and love so much. Just needs a bit more red to make everyone happy. :naughty:

 

[AvidHiker]

I would imagine an advanced measurement setup, especially one with an integrating sphere, would certainly not be affected by color.

However, does anyone know if your basic (relatively inexpensive) lux meter has a flat response to all frequencies of light? I think this would be the requirement for making accurate comparisons of output. But, practically speaking, I suppose what's most important is how your eyes perceive the brightness. I think a cooler tint should be percieved as brighter as your eyes are more sensitive to the blue and of the spectrum in low light conditions.

 

[2xTrinity]

the integration sphere and meter that measure lumens doesn't care about color. It will measure total light energy. Meaning if its 16 lumens of green its 16 lumens. If its 16 lumens of red its 16 lumens. Your eyes will think the green is brighter than the red because of the difference of receptors in your eye ball, but if they were both 16 lumens to start the meter would read it correctly.

What you are describing is radiated power. Lumens are a meaure of radiated power weighted by how bright they appear to human eyes.

1 watt of radiated green light is defined as 680 lumens
1 watt of red light is about 240 lumens
1 watt of UV or IR light is 0 lumens

If two lights have the same number of lumens, they will appear to have the same brightness (unless talking about night vision or peripheral vision)

The black curve on the above graph is the luminosity function, used to define lumen output. The green curve shows our eyes night-vision sensitivity.

In order to get an accurate lumen measurement, a lux meter would need to take samples at just about EVERY wavelength in the visible range, and weight them by that funciton. Most only sample RGB as far as I know though, and then "estimate" what the true curve of the light source is. That is why many lux meters have settings for incandescent, fluorescent, and daylight. If they actually measured all wavelengths, there would be no need to "tell" the meter what sort of light source is being used.

For that reason, LEDs could produce highly inaccurate results for a meter expecting daylight, fluorescent, or some other light source with a completely different power distribution curve.

Brighter emitters are typically cooler because of characteristics of the phosphor and its deposition. Irrespective of differences in die, a heavier coat of phosphor will result in a warmer tint, but will also block more light than less phosphor.

cooler light is not inherently more efficient though. And as the phosphor deposition process is improved, I believe neutral-white emitters will start to become the most efficient (3500k-5000k range). Assuming they were to come up with a 100% efficient phosphor process, or emit white light directly, a white balance at around 3500k would be the most lumens/watt because our eyes have lower sensitivity to blue light, as indicated on the chart above.

So for the most part the phosphor isn't "blocking the light" its creating most of the "white" light that you see. But of course if they put it on too thick it would get dimmer as the blue light wouldn't make it to excite the phosphor at the front as much. Its a delicate balance but the phosphor is making the light that we see and love so much. Just needs a bit more red to make everyone happy. :naughty:

This is easier to understand in systems based on UV light. Without a phosphor there, lumen output is ZERO. The best way to get red light is to actually include a separate red phosphor, like fluorescents have been doing for years.

 

[MrGman]

The integration Sphere has no selection for "type of light" input. I and the optics engineer that uses it most, have put green, blue and red LEDs in it and it gives the accurate "calibrated" reading of all without having to select anything. I did learn that it does have the color curve you show below programmed into it, but no separate selection for what the wavelength that is coming in is necessary.

Thanks for the correction on what we see and how we see it.

I don't use the spot Lux Meters for anything other than reading fluorescent backlight sources (rarely). Not the main focus of my work.

I still love my Fenix T1. It is brighter than anything else I own, It would be nice if it had a little more red in it, but I am not tracking blood trails in the woods or trying to figure out if someone has an infection in their throats.

If it blinds a perp or a pitbull, I am more than happy.