"R" bin luxIII beats "U" bin flat out in brightness.

IsaacHayes

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Yes that's right. I compared both my Cyan and my white U-bin lights. Both regulated. The cyan measured at ~970ma (dual bb500's) and the white measured at ~930ma (wizard2 917ma) at the leds. My personal cyan has a flux of R bin, but the white is a flux of U(X1J).

The Cyan walks ALL OVER the white. This is outside, at night, with the lights on, with the lights off, it doesn't matter. The cyan totally imposes it's self over the white beam. I have a ~60lumen lux1 r/o on low alkalines so it's probably not up to snuff at the moment, and the white walks over it...

Doing a ceiling bounce test the outcome is the same. The Cyan seems 2x or maybe even 2.5 times brighter. You can have both on, then turn one on/off, notice the change, then do the same to the other, and notice less change.

All lights are using the mag C/D reflector BTW.

Is it really just your eyes more sensitive to this color? This is a real cyan colored not a greenie. I've noticed royal blue as being redicolously bright like this as well...(eyes aren't supposed to be that sensitive to it) Or is the stuff they use to measure white/colored light not as acurrate for one or the other??

Pretty amazing the cyan 2C light I have, but puts my nice white light to shame!!
 

xpitxbullx

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Light meter wont lie to you. I think you can just see the 'odd' color more easily but that doesn't make it brighter.

Jeff
 
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IsaacHayes said:
Yes that's right. I compared both my Cyan and my white U-bin lights. Both regulated. The cyan measured at ~970ma (dual bb500's) and the white measured at ~930ma (wizard2 917ma) at the leds. My personal cyan has a flux of R bin, but the white is a flux of U(X1J).

The Cyan walks ALL OVER the white. This is outside, at night, with the lights on, with the lights off, it doesn't matter. The cyan totally imposes it's self over the white beam. I have a ~60lumen lux1 r/o on low alkalines so it's probably not up to snuff at the moment, and the white walks over it...

Doing a ceiling bounce test the outcome is the same. The Cyan seems 2x or maybe even 2.5 times brighter. You can have both on, then turn one on/off, notice the change, then do the same to the other, and notice less change.

All lights are using the mag C/D reflector BTW.

Is it really just your eyes more sensitive to this color? This is a real cyan colored not a greenie. I've noticed royal blue as being redicolously bright like this as well...(eyes aren't supposed to be that sensitive to it) Or is the stuff they use to measure white/colored light not as acurrate for one or the other??

Pretty amazing the cyan 2C light I have, but puts my nice white light to shame!!

Searching t3h Google for keywords scotopic and photopic lumens might bring you a lot of ideas.
 

nerdgineer

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chevrofreak said:
..we saw massive differences between meters in how they read certain colors of light...
Agree. Matching spectral response of sensors is normally lab stuff way outside any normal application of light meters, but all the different types of sensors, selenium, silicon, CdS, etc. respond to colors differently. I think the human eye is particularly sensitive to green.
 

UnknownVT

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1watt LEDs - Blue vs. White -

FenixL1PB_Civic2Udesat.jpg


The photo was colored originally and the and it was DEsaturated of the color - ie: hopefully all I did was to get rid of the color leaving only the luminance information.

please see this thread -

Fenix L1P with Color LEDs

and a more detailed explanation of the beamshot "desaturation" of color -
please see Post #309 - Inova X1 Spot Blue - which got merged/buried in the long thread New Inova X1?
 
Last edited:

IsaacHayes

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pitbull, I wish I had one, I'm curious to see what it "sees".

Even if our eyes see cyan (mine is ~488nm argon laser blue) better, that is still cool, and wow what a HUGE difference. Didn't realize it until I compared it against white directly.

U-VT: You stated that red/blue look bright with green not as much. But the camera seems to see green as the brightest. Cameras see differently than our eyes obviously! BUT green should be to our eyes the brightest over red/blue... odd!!
 

UnknownVT

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IsaacHayes wrote: "You stated that red/blue look bright with green not as much. But the camera seems to see green as the brightest. Cameras see differently than our eyes obviously! BUT green should be to our eyes the brightest over red/blue... odd!!"

I'm kind of confused by what you're asking/saying.

In my Colored Fenix review the Green was simply not as bright as either the Red or Blue - and by DEsaturating the colors from the photo it does seem that way.

Our eyes are most sensitive to green - but if another color is physically brighter - it normally should appear brighter - that's why I desaturated the colors from the beamshots - just to show the luminance/brightness component of the lights (without the color) so that one could compare the brightness directly without being distracted by the color.
 

IsaacHayes

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Hmm on my monitor the green looked brighter in the desat pics. :shrug: The green likely had a higher Vf than the others.
 

UnknownVT

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IsaacHayes wrote: "on my monitor the green looked brighter in the desat pics. :shrug: The green likely had a higher Vf than the others."

OK I think I see what you're getting at -

I'm looking at the side-spill - the Blue and Red obviously have a LOT more than the Green.

However I do see that the Green seems to have a brighter hotspot.

Perhaps there's where we have our wires crossed.

FenixL1P_RBGdesat.jpg
 

easilyled

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I can't quite work out why the light meter is always regarded as the bible.

Doesn't it only measure lumens at any one given point (ie. hotspot) rather
than overall output?

So only an integrating sphere would give a true value of relative output - short of that a ceiling bounce test with the eyes is more valuable than a lightmeter for total output IMHO.
 

CroMAGnet

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easilyled said:
I can't quite work out why the light meter is always regarded as the bible.

Doesn't it only measure lumens at any one given point (ie. hotspot) rather
than overall output?

So only an integrating sphere would give a true value of relative output - short of that a ceiling bounce test with the eyes is more valuable than a lightmeter for total output IMHO.
Regarding this very good point and relative value.

I use my light meter to measure lux just like you are saying here but I also use it to measure relative output.

I simply place the whole head on the sensor so it gets saturated will all of the output of the flashlight. When doing this method to compare both lights to each other separately I get a relative output copmarison. I think this is a good way to tell the (once again) relative output of two white lights. (That aren't too bright to go off the scale on the light meter) :)
 

IsaacHayes

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VT: hmm I'm thinking that perhaps the blue isn't as focused as well as the green in the reflector, as it's got more sidespill and less hotspot. It could be physically up/down in the reflector, or the wavelength of light is reflected differenlty as that is true also.

An IS can read different for different colors too, though.
 

wasBlinded

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A typical light meter has very poor accuracy when measuring colored LEDs, and will be extremely misleading if you are trying to compare the luminous flux of different colored LEDs. For more info, see the Lightmeter benchmarking thread in the Batteries & Electronics section of CPF.
 

easilyled

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Thanks CroMagnet for clarifying that for me.

So many here say the lightmetre is the only accurate way of comparing
the relative brightness between 2 similar lights or the same light
with leds swapped, but I always wondered how you could compare total
output without an integrating sphere.

Not having or seeing how a lightmetre works I didn't realise that
by saturating the sensor, one could compare total output.

I'm still not 100% sure that this is completely scientific though unless the
lightmeter is specifically designed for this. For instance the sensor may still
measure the most concentrated part of the light even when the sensor has
the light up against it - or am I mistaken?
 

CroMAGnet

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easilyled said:
I'm still not 100% sure that this is completely scientific though unless the lightmeter is specifically designed for this. For instance the sensor may still measure the most concentrated part of the light even when the sensor has the light up against it - or am I mistaken?

Yes very good observation. And what people do to get around this is they tape the LUX meter inside a milk carton and flood the inside of the carton with light from the flashlight through a bezel diameter hole. This evens out the light similar to an integrating sphere. Again, it's not scientific, not necessarily optimal for accuracty but you get a good relative idea of the output differences.

Another thing we do is... get a large white pail, like the orange painter's buckets at Home Depot, only white. The sureface area is approximately 1 square foot. Then we take a 1-meter long ruler and tape it to the outside, starting from the bottom on the pail. We then place a LUX meter at the end of the ruler and shine the light into the bucket/pail from the same area, 1-meter away from the bottom of the pail. The reading that you get on the LUX meter is actually the number or LUMENS of output. This is probably not accurate but it is definately a good releative indicator and close in accuracy to the accual lumens :)
 

xpitxbullx

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The cyan Lux-I LED is rated 'R' at what current? And you are pumping 970ma into it? Perhaps it's brighter if the rated current is 350ma and you are tripling it. If thats the case, the LED won't last for long.

Jeff
 

Planterz

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That was my though too. You can overdrive anything to make it brighter/faster/stronger, even beyond what the supposed cutting edge technology is, but chances are you're going to burn it out. I remember being seriously impressed with a minimag bulb when I stuck it on a 9V battery, until it fried.
 
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