Headlight HID lamp comparison.

Corned

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If you're interested...

I did a comparison between some different colour temperature lamps in my HID projecstrs earlier this week. Bit of a boring subject, but I thought the results were quite interesting.

I recently tried some 6000K lamps, just to see how they performed after my tired 7-year-old 4300Ks.

Initially, the change looked quite impressive. The light output was noticeably better, and the way they picked out reflective road signs, particularly on open motorways, was very good. However the way they lit the road surface was not so impressive, and although it was better than the old 4300s I felt it was still a little lacking.

So I got hold of a set of 5000Ks and set up a little experiment. I waitined until night time and set up a light meter about 4 metres in front of one of the headlights. With the 6000Ks still in, I fired them up and gave them 10 minutes to get fully up to working order. Then I took the reading.

Next, I put back in the old 4300s, and again took the reading after letting them warm up properly.

Finally I put in the new 5000Ks and let them burn in for an hour before taking a reading. The results are as follows:

4300K - 635 lux.
6000K - 786 lux.
5000K - 1024 lux.

I was aware there would be a difference, but the level of difference was quite surprising.

The moral of the story? There are two:

1. Blue might look 'cool', but it's ****** useless for lighting your way! :rolleyes:
2. Old HIDs really drop off in performance over time.
 
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television

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That was nice to know, thank you :D Certainly an interesting subject, How old were the 4300k in the test.
 
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That was nice to know, thank you :D Certainly an interesting subject, How old were the 4300k in the test.

As stated above - 7 years old. ;)

I have no reason to think they are not the OEM originals supplied with the car when new.
 

television

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As stated above - 7 years old. ;)

I have no reason to think they are not the OEM originals supplied with the car when new.

Thank you, that is quite a drop off in light output and all the more important to replace say 4years old bulbs in pairs

Thank you
 
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^ Agreed!
 

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Do the bulbs age with time? (maybe through gas pressure reduction), or only through use?
 

television

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Do the bulbs age with time? (maybe through gas pressure reduction), or only through use?

There is always an erosion of the elements in all lamps, some have a better life than others
 

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Thanks for doing this test. £50 buys a couple of D2S bulbs so I may give mine a swap and see the difference.

Has anyone changed an R230 offside bulb without removing the bumper? (to remove the headlight unit). I've practiced on the nearside and the procedure is simple.

Is it just a case of squeeze your hand in and have the plasters ready?
 

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How much does the sensitivity of the light meter vary with colour temperature?

If the Lux is a logarithmic scale like the Bel & decibel then the change between 635 and 1024 Lux will only just be perceptible.

The fact that the difference appears quite distinct is partly because the eye can determine the colour difference very clearly

The only test that counts is which one is best for night driving?

Nick Froome
 
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I'm a lighting engineer by trade, so I could bore you all to death with such rivetting topics as photopic and scotopic sensitivity, light wavelengths, lumens and pupil lumens. But I won't...

I'll let you know how the night driving fares after the weekend! A late-night return trip from the outlaws down the M1 is the acid test.
 

television

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I'll let you know how the night driving fares after the weekend! A late-night return trip from the outlaws down the M1 is the acid test.

Do you dislike them that much :rolleyes:, but if you see the light you will get to heaven so they say;)
 

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But there is more to this than just the LUX of each bulb type/colour. Our eyes can identify objects better with certain wavelenghts
 
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^ But I just made a promise that I wouldn't bore you all to death about that stuff... :rolleyes:


:D
 
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Miffy

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I made a promise that I wouldn't bore you all to death about that stuff... :rolleyes:


:D

please do. I am sure a good few of us would be interested on your take of HID / Filament /Colour Temp / Eye Sight
 

television

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I am very interested in these subjects :D:D
 

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Ok it's got me hooked !

I have been thinking about changing the HIDs in my SL as I've heard they deteriorate with time
 

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Please, help us to see the light.
 
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Here is an excerpt from a paper which we devised for use by my business, which is in the industrial/commercial lighting sector. Please forgive the industry-specific terminology and occasional product references.

But it will give you an idea of why Miffy is right to question light meter readings whern the capability of the meter is not known.

"Scotopic and Photopic Ratio Technical Data Sheet July 2009

Many people, who see Induction lights, comment on how bright they appear and on what they feel is a higher quality of light being emitted from the fixtures. However, when individuals compare Induction light to a conventional lamp with a light meter, the Induction lamp is generally measured as producing less light than the conventional lamp. This has led some people to question the installation of these fixtures - even though they use 50% less energy – as they expect that the areas lit by them will not be bright enough when compared to conventional lighting. All this, even though their eyes are telling them they are the same if not brighter.

The issue is not with the Induction technology or the ability to produce acceptable light. Today’s standards for light meters are calibrated using outdated methods. They have not evolved with advancing technology in the lighting arena. This standard used to set the sensitivity curve for light meters does not take into account the contribution of Scotopic vision (night vision) to the sensitivity of the eye. Scientific studies have shown the eye is more sensitive to blue wavelengths than the measurement curve of the light meter. Blue light, acting on human night vision (Scotopic vision) is largely responsible for “visual acuity” or sharpness of vision. Simply put, light meters by which they measure light are wrong. Consumers are therefore paying for products with yesterday’s lighting quality while not taking advantage of today’s products, such as Induction lighting that offer reduced costs and a better quality of light.

The human retina contains some 125million rod cells and some 6 million cone cells. These respond to different frequencies (colours/ wavelengths) of light in different ways. Cone cells are adapted to detect colours and function well in bright light, while rods cell are more sensitive but do not detect colour well as they are adapted to low light.

Photopic Vision is the scientific term for human colour vision under normal conditions during the day (i.e. human perception of red, green and blue that the brain integrates to form full colour images of the world around us.)
Scotopic Vision is the scientific term for human visual perception in low light (night vision).

Mesopic Vision is the scientific term for the combination between Photopic and Scotopic vision taking into account the total sensitivity of the rod cells in the eye for the blue range, with the colour perception of the cone cells.
The ratio of Photopic light vs. Scotopic light in a lamp is called the S/P ratio. This ratio determines the apparent visual brightness of a light source. This is why an Induction 200w lamp will appear as bright or brighter to the human eye than a sodium vapour or metal halide of twice the wattage.

Here’s how it actually works:
Light is measured in Lumens (Lux). The S/P ratio of a lamp is important as it provides a number that can be used to multiply the output reading of a lamp using the outdated standard conventional meter to determine how much light, which is useful to the human eye, a lamp produces. These are known as Visually Effective Lumens (VEL).

Using a conventional light meter, the light is measured to determine the photopic vision sensitivity curve. Using the same light source with a light meter calibrated to the scotopic, the scotopic sensitivity curve is determined. The resulting readings form an S/P ratio that can be expressed as a single number."

The meter I used is one which would 'fail' the test above. However ones which measure a fuller mesopic range are available, if cripplingly expensive.
 
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Corned

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I also found this little nugget:

d2slumen.jpg
 
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