[faztaz]

Looking to replace the fog lights with bulbs that match my bi-xenons without having to actually install HID on my X3 MSport. Any suggestions and to which brands/color spectrum will closely match?

[romanonj]

I will be interested as well....

[The X Men]

Hoens is pretty good.

[RhoXS]

If your interested in appearance trumping good lighting then there are a number of expensive replacement bulbs out there that will approximate the appearance of HID lamps with a bluish color to them (to one degree or another). These bulbs are still based on an incandescent element. The energy output of an incandescent bulb, even higher efficiency quartz halogen bulbs, exists in all visible frequencies but is dominated by energy in the yellow region of frequencies, not blue. Since it is impossible to add more blue light to a any given incandescent bulb, the only way to make it appear bluer is to filter out much of the useful and predominant yellow energy so the blue that does exist becomes a higher percentage of the total. This is done with a so called dichroic filter and is why the quartz or glass envelope of these bulbs appears to be blue (it lets blue frequencies through but reflects/blocks some percentage of yellow frequencies). The end result is a bulb that puts out less light. Blue light is also highly reflective by water vapor whereas yellow penetrates water vapor. So, not only will you see less with these replacement HID wannabe bulbs, your visibility in mist or fog will suck. That is why fog lights are sometimes intentionally designed with yellow lenses.

HID lamps provide a spectrum of energy that is mostly uniform across the entire visible spectrum and that is why they appear so white. The little bit of blue that is sometimes seen represents a very minor fraction of the total light output.

[fjrmann]

Originally Posted by RhoXS

If your interested in appearance trumping good lighting then there are a number of expensive replacement bulbs out there that will approximate the appearance of HID lamps with a bluish color to them (to one degree or another). These bulbs are still based on an incandescent element. The energy output of an incandescent bulb, even higher efficiency quartz halogen bulbs, exists in all visible frequencies but is dominated by energy in the yellow region of frequencies, not blue. Since it is impossible to add more blue light to a any given incandescent bulb, the only way to make it appear bluer is to filter out much of the useful and predominant yellow energy so the blue that does exist becomes a higher percentage of the total. This is done with a so called dichroic filter and is why the quartz or glass envelope of these bulbs appears to be blue (it lets blue frequencies through but reflects/blocks some percentage of yellow frequencies). The end result is a bulb that puts out less light. Blue light is also highly reflective by water vapor whereas yellow penetrates water vapor. So, not only will you see less with these replacement HID wannabe bulbs, your visibility in mist or fog will suck. That is why fog lights are sometimes intentionally designed with yellow lenses.

HID lamps provide a spectrum of energy that is mostly uniform across the entire visible spectrum and that is why they appear so white. The little bit of blue that is sometimes seen represents a very minor fraction of the total light output.

Most outstanding post, sir! Thank you for taking the time to inform.