One Xenon Bulb turns to purple/pink

[Billias]

Hey all,

I think it is time for my Megane II (2006) to replace my xenon bulbs. It has factory fitted Xenon.

What is the type of Bulb I need? are there choices? or just one bulb?

[Billias]

My Megane II phase2 does it use D2S or D1S?

[MilosB]

you should have d1s bulbs,
I recommend doing the change ASAP and to do it in a pair as the other is very likely to fail very soon,
you have few options,
OEM at 4300K

Philips http://www.powerbulbs.com/eu/product/xenon-vision-d1s-85415-single or
Osram http://www.powerbulbs.com/eu/product/osram-xenarc-d1s-xenon-hid-bulb-single

Uprated 4300K Osram *my recommendation* http://www.powerbulbs.com/eu/product/osram-night-breaker-unlimited-d1s-single

and for styling (pure white, not recommended for bad weather areas)
Philips 4800K http://www.powerbulbs.com/eu/product/xenon-x-tremevision-d1s-85415-single or
Osram CBI at 5000K http://www.powerbulbs.com/eu/product/xenarc-cool-blue-intense-d1s-single

Be avare of fakes as they are a lot of them, ones linked come from a reputable seller

[AlexB]

Choose the lowest colour temperature because our eyes respond better by pupil dilation/contraction to yellow light, which is safer. Just remember how uncomfortably hazy neon blue lights look...


It's quite simple, actually. We have two types photoreceptors in the eye retina, whose sensitivity is shown in the following diagram.

The second left bell curve is for the "rods", i.e. b/w low light vision (centred around blue-green), two right curves are for the day-time vision "cones", the leftmost curve is for what we see as blue. Unfortunately, our eyes better adapt to the light registered by the "cones" on the right. So, blue headlights are more likely to dazzle, and they kill our rod-base night vision. Older people suffer of this more due to naturally diminished adaptation ability.

This is the reason selective yellow filters were used in France in the past. At some point they were abandoned due to an erroneous study, which showed no advantage of yellow filters, possibly because the bulb power was not increased to compensate for the losses in the filter, plus there was not much of blue in the spectrum of halogen bulbs anyway. Perhaps, it was impractical in 1976 to demand introduction of a more powerful bulb, which would have led to modifications to the headlamp thermal design and doubling the alternator power. With HID and LED technology these considerations are gone, there is plenty of blue for the "rods" in the low-temperature HID, so just choose the lowest available colour temperature (which is still white) and the maximum light output within legal limits.

Besides the reason there also exists aesthetics, i.e. subjective preference. As we are pretty much used to cognitive dissonance due to the nature of the modern society, blue lights may be perceived as excitingly disturbing. This is how they are sold...

[MilosB]

very nice write up Alex

most powerful and warmest color teperature is 4000K 4000lm Koito bulbs, but they are only sold in Japan. next to them is Osram NBU at 4300K and 3200lm,

[AlexB]

Both should be OK. Our eyes recognise different colour temperatures as neutral white depending on the ambient illumination. In bright sunlight 6500K is white and at night 3400K.

This is why we are adjusting the colour temperature and brightness of the computer displays throughout the day.