Reply With QuoteWell, for one, you don't show any influence of the ellipsoid lens on the light pattern. Your diagram implies the reflector is solely responsible for the direction of light. In other words, you've accounted for reflection but not refraction.
Major Contributor
Some more thoughts on headlights
There's been a lot of talk lately about headlight modifications and so I wanted to share some thoughts with you guys. I work with lighting and lenses a lot, but I am by no means an engineer, so feel free to prove me wrong.
Our cars were designed to run with 9006 bulbs for a reason. I suspect the opaque tip serves some specific and crucial function for directing the light rays to where they are supposed to go (the road) and away from where they aren't supposed to go (people's eyes).
I made this crude diagram to illustrate my hunch.
This is based on my observations of how the light shoots out of the projector lens on our cars. (For those of you with out projectors, this doesn't really apply.) So if the tip is removed, I wonder if more of that light gets directed toward the wrong places. I probably have the reflector shape wrong and there may be another lens that I haven't accounted for, but I think the question is still valid. So, please, let me know your thoughts. All in all, I still plan to upgrade to HID as soon as I get the extra cash.
BennyM
Major Contributor
Well, for one, you don't show any influence of the ellipsoid lens on the light pattern. Your diagram implies the reflector is solely responsible for the direction of light. In other words, you've accounted for reflection but not refraction.
Major Contributor
yea what he said.....Originally Posted by BMWCCA1
Major Contributor
Well, I guess that's my main question
What is it that creates the cutoff at the top of the light pattern? Is it the reflector combined with the painted tip or is it the lens(es)? Does anyone have a picture of the light pattern after a 9005 conversion?
BennyM
3 Grand Master
the cut off is not dependent on the bulb...euro cars have H1 bulbs,which dont have a painted tip....I dont see the point of your post Benny...at first i thought you were going to say our cars shouldnt have hids....but then you say you are going to get them anyway?
Last edited by Paul in NZ; 12-03-2008 at 02:24 AM.
Gone but not forgotten
2 Grand Master
One of my pet peeves: Poorly directed headlights.
Ralph Mendoza Jr. - Long Beach, CA
5-10 Grand Master
i don't think all that much light comes from the tip of the bulb as that is the small end of the filiment, and what does make it through gets handled by a decent lens, i think the painted tip if more for the shitty plastic 90s lights with pretty much no containment, like my truck, the lights on it blow ass
all america wants is cold beer warm cat and a place to take a poop with a door on it
Big, Big Time Poster
the ellipsoid cutoff is done with a piece of metal just behind the projector lens. i'll try and get a pic of one that I have disassembled at home.
2 Grand Master
Exactly. The black tip does not impact the light pattern much, if at all. I noticed this when I did the 9005 bulb conversion. BTW, HIDs work great with ellipsoids (duh). One of the best mods I have done.
Thanks,
1995 525i Auto, M50TU 2.5L, EAT chip, 1/95 build, USA, 205/65/15 tires, ASC+T, HID, lumbar, EC Mirror, BMW Alpine 5 radio with BMW-Pioneer CD Changer, abt 236k miles, Oxford Green/Parchment
Major Contributor
It's the outer lamp lens, at least with our lights. That's why RHD cars traveling in Europe use a stick-on mask to kill the glare to oncoming drivers. There's also a metal "shield" as part of the ellipsoid lens holder that some people modify to improve the light pattern, as mentioned above. The reflector is pretty much parabolic and symmetrical.
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