# 4200k Vs. 6000k HID Visibiltiy



## rustlerdudr987 (Jul 31, 2012)

So i have been lurking on this forum for some time now and i was reading something about 4300k bulb temps being something like 55% brighter to the human eye than say 6000k because it mimics the sun but i don't quiet understand. Could some one please clear this up and tell me how this works and what is the brightest to our eyes.


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## Fusion_m8 (Jul 31, 2012)

http://www.candlepowerforums.com/vb...mpared-to-Magic-Scorpion-40W-and-85W-Ebay-HID

Have a look at the pictures in the above thread, you can see that the 6000K bulb makes things appear faded, colourless and washed out. The slightly yellowish beam of the 4300K bulb adds more colour, and detail as its easier for our eyes to pick up the light that is reflected back from objects that the light falls on. 

Perhaps if you are still chasing a more scientific explanation, you can speak to an eye surgeon at your local hospital.


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## blasterman (Aug 1, 2012)

I agree with the conclusions about ~4000k bulbs being superior for hand torches and night lighting in general, but the reasons are different that stated above.

HID, fluorescent, LEDs etc are not continuous light sources, so their comparison to the relative straight spectrum of the sun is simply not valid. Also, our eyes have the greatest sensitivity to blue green, around 500nm. This means that if you measure the lumen out-put of a 6000k bulb -vs- a 4000k one, and the bulbs are otherwise from the same series and wattage, the 6000k bulb will score higher because it has a stronger wavelength in the blue-green region. So, this is kind of the same photopic -vs- scotopic debate that high pressure sodium advocates have been arguing for decades. An engineer and a biologist would likely give you two different answers, with both being right.

So, our eyes are most sensitive to 500nm, and the light with more spectrum in this range will have the higher lumen count on the box. Big deal. Our best vision at night only works good if you include longer wavelengths in the mix. 6000k might get attention better than 4300k, which is why those high powered Xenon searchlights you see at night promoting events are typically around 6000-6500k. However, for best depth perception and over all color rendering practical light sources need to be lower than that. Quite simply, when you're walking around the woods with a HID flashlight, or even watching an NFL football game lit with HID lights, do you want to notice the color and intensity of the light, or concentrate on what it's illuminating? The answer under most circumstances, unless you're lighting a parking lot to keep out thieves or illuminating B-17's ,is typically the later, and the beam shots prove this.


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## rustlerdudr987 (Aug 1, 2012)

Does that mean by concept that a 5000k bulb with be the best of both worlds per say?


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## BVH (Aug 1, 2012)

5000K is the sweet spot for my eyes. 4300 is too yellow, 6000 is to blue


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## Fusion_m8 (Aug 1, 2012)

rustlerdudr987, there's your eye surgeon for you...



blasterman said:


> I agree with the conclusions about ~4000k bulbs being superior for hand torches and night lighting in general, but the reasons are different that stated above.
> 
> HID, fluorescent, LEDs etc are not continuous light sources, so their comparison to the relative straight spectrum of the sun is simply not valid. Also, our eyes have the greatest sensitivity to blue green, around 500nm. This means that if you measure the lumen out-put of a 6000k bulb -vs- a 4000k one, and the bulbs are otherwise from the same series and wattage, the 6000k bulb will score higher because it has a stronger wavelength in the blue-green region. So, this is kind of the same photopic -vs- scotopic debate that high pressure sodium advocates have been arguing for decades. An engineer and a biologist would likely give you two different answers, with both being right.
> 
> So, our eyes are most sensitive to 500nm, and the light with more spectrum in this range will have the higher lumen count on the box. Big deal. Our best vision at night only works good if you include longer wavelengths in the mix. 6000k might get attention better than 4300k, which is why those high powered Xenon searchlights you see at night promoting events are typically around 6000-6500k. However, for best depth perception and over all color rendering practical light sources need to be lower than that. Quite simply, when you're walking around the woods with a HID flashlight, or even watching an NFL football game lit with HID lights, do you want to notice the color and intensity of the light, or concentrate on what it's illuminating? The answer under most circumstances, unless you're lighting a parking lot to keep out thieves or illuminating B-17's ,is typically the later, and the beam shots prove this.


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