I was under the impression that most car headlights used halogen bulbs nowadays, as opposed to tungsten. Is this correct?

I own a car but I mainly ride my motorcycle. While learning to ride a motorcycle I took a Motorcycle Safety Foundation course where they advised us to drive with our main beam headlight on during the day-time to increase visiblity. The idea is to make it easier for inattentive car drivers to see you. I use dipped beam around town at night, of course, but, irrespective of ambient light levels, I'll keep my main beam on in the afternoon/evening until I see a sufficient number of cars with their headlights on.

What I really object to is people who don't use headlights when it's dark, but rely on parking lamps and fog lamps instead. Can't the police fine you for this? Why don't they?

the new bluish-white headlights of which you refer are known as high intensity discharge (aka HID) lights. they are similar in design to mercury vapor lights (bluish streetlights), high pressure sodium lights (orangy-yellowish streetlights) and metal halide lamps (similar to mercury vapor, but more versatile). they're efficent, they last forever and are durable as hell. they used to be used only in industrial applications, but new designs have allowed them to be put into cars for our collective annoyance.

i find myself staring at these types of headlights because they're really pretty, much in the same way i can't help but stare at the beautiful blue light of arc or tig welding. i'm not usually attracted to shiny objects, but these just seem to hyptonize me every time.

NOTICE TO CONSUMER: Most lamps we sale are intended for use solely as auxiliary lighting. All lamps are not intended to be used for headlight purposes, nor are they certified for headlight usage. Lighting laws vary from state to state. Next Collection makes no representation or warranty, either expressed or implied, as to the legality of its products for street use on any vehicle or in any location. Most lamps & light bulbs are designed to improve visibility during nighttime motoring and inclement weather conditions. However, irresponsible use of any auxiliary light can be dangerous and illegal.

Disclaimer from http://www.eautoworks.com/ on a "Blue Ion Headlight Film" described as "After you put this blue ion headlight film onto your car, when you turn on your headlight, the light come out with have a little blue tinted color."

Many high end cars today have a high intensity discharge light as headlights. These are often in the form of fog lights, though not always. While these may look cool or have a wider area of coverage the thing to realize here is that they are not safe and blue bulbs are illegal for several reasons.

Not Safe?

Well, you, the driver behind the wheel are more visible to others (painfully so) and have a wider area of coverage, this is often not a good thing.

Adding a blue film or filter over the bulb drastically reduces the amount of light (photographers talk in stops - the filters often cut the amount of light in half or more). When this filter is placed on a halogen lamp (which is already rather poor in blue light) very little light gets out and that is dangerous for you the driver - both in terms of visibility to others and what you can see.

On the flip side, the blue light scatters more than the yellow that is classically seen in headlamps. This has a twofold effect - first less light gets to the ground, and more light gets to the eyes of the other drivers. In bad weather conditions such as rain, fog, and snow this scatters even more.

What is likely the most annoying part of blue lights is that when you look at them the color is registered as more intense. This is partly because our eyes are more sensitive to blue light than yellow. Blue light furthermore does not trigger the pupil to close as fast as yellow or white light - so more light gets into the eyes and effectively blinds the person for a short time. This is known as over stimulation of Retinal Purple.

Illegal?

Yes - blue bulbs are illegal. It says so quite spelled out in the requirements. The only colors permitted are white and yellow for headlights. For example, from the Canadian Vehicle Safety Standard #108 and #108.1 clearly state that "all light issuing from the front of a motor vehicle for illumination purposes must be WHITE, WHITE-TO-YELLOW, or YELLOW". The document for the United States is FMVSS108.

Realize, that true HID lights are legal (but still just as annoying to other drivers) because they emit a very powerful white spectrum which has a noticeable blue component (and certainly more blue than the halogen lights of the other cars - our brain is notoriously bad about perfect color recognition).

Having red or blue lights on the front of a moving vehicle that is not an emergency vehicle is also quite illegal. No matter how strong people push and complain this is not likely to change.

State laws may also vary. Furthermore realize that none of this applies to off road situations... but then you're not the idiot driving down 101 at dusk with bright blue bulbs.

Europe (where many of these high end cars are made) has a number of regulations on the books about the light from headlamps. France, for example, required headlamps to produce less blue in the lights (while HID are strong in blue) for the specific purpose of reducing glare. European regulators state that a car with HID lamps must have a system to dynamicly level the headlights (so when driving up or down an incline the lights remain pointed at the ground, likewise when carrying a significant weight the car front doesn't point up). This increases the weight and the cost of the headlamps.


http://www.possi.com/bluebulb.htm
http://lighting.mbz.org/faq/

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