Citroen XM Forum

Found this an interesting read, and echoes my own experience...
http://www.mynewsdesk.com/uk/rac/pressr ... essrelease

Many post-halogen headlights seem to work more as floodlights than properly profiled and focussed beams, with little control of scatter, and sometimes a real difficulty in telling main from dip.

The tendency towards blue light only makes this worse, since blue (shorter wavelength) light scatters more than the (longer wavelength) red-yellow-green end of the spectrum. It's the reason why sunsets look red; the blue light from the sun is scattered into the atmosphere and space, leaving the red-end to punch through.

As John and others have often pointed out, unapproved HID/blue conversions can be amongst the worst for scatter and dazzle, especially in headlight units not designed for them.

I think that modern headlamps tend to be too bright. Over the past few years I've had to do a lot of night driving for work and was always flashing on-coming cars thinking that they had full beam on only to get a massive blast of light back in reply. You would think that these drivers would get sick of getting flashed and perhaps start to wonder why.

I started wearing those supposedly "anti dazzle" glasses and have to say that I do think they helped.

Also, overly bright headlamps make it harder to see past them and to pick out other vehicles that may not have such bright lights.

Still, overly bright headlamps not such a problem for us XMers, eh?

I would concur, its sometimes difficult to distinguish dipped lights from main beam but I think a lot of the problem is misalignment although headlights in general seem to vary from car to car. I was looking at the approaching traffic on the M5 the other night and you often see rows of cars with an acceptable light pattern and then the odd one or two that blind you.

Relatively modern headlights are certainly brighter, I think my 406 head lights are the brightest I have ever had in 60+ years of motoring and they are very white indicating they have almost full battery voltage. The XM headlights were abysmal on dip.

Peter

It's not always related to new type of headlamps. I'm on the road (work) every night and quite often get dazzled by other vehicles, due to inappropriate installation of light bulb. So even on dipped mode the beam from headlight goes up towards the sky (unfortunately some lorry drivers have a problem with replacing and fitting a light bulb in right way too).
And from the other side. Just wondering how is possible that these 'yellowish bulbs' are legal to use ? I saw few vehicles with 'warm white' lights and must admit that impressed that they can drive in the night time with such a poor visibility

Probably no accounting for tastes [emoji9] but I had yellow bulbs in all my Citroëns, except for the Xm (and not just slightly yellowish tint but the real, strong one). And I really liked them. No complaints about poor visibility at all. I wouldn't hesitate for a single moment now if any of the major vendors provided their usual ultra bright bulbs we all use in yellow.

Hi Prem

Yellow and white are the permitted colours for headlights.
The requirement is that individual pairs of lights must be the same colour. not that they must be white.
The XM when introduced in May 1989 was supplied with yellow headlight bulbs.

In practice strong Blue light is more than twice as irritating to the eye as strong yellow light.
Yellowish light is far better than bright white in fog or mist.

As you point out bulb aim is critical to controlling dazzle.
Effects of dazzle are directly related to light intensity and volume of blue component in the light.
Bulbs we see as pure white contain a significant blue component.

Headlight intensity is a separate problem.
In the UK intensity was controlled by permitted bulb type and wattage.
Then HID bulbs came along with nearly five times the light intensity for the permitted wattage.
Even the low wattage version HID's give three times the light intensity.
There were steps in the UK to restrict the use of HID's but they obtained EU approval.
Retro fit HID's with Halogen reflectors are not legal for road use in the UK.
The market is flooded with retro kits and control of incorrect use virtually impossible.

From what I have seen recently the rapid advances with LED lighting will overtake both Halogen and HID.
The LED motorcycle headlamp bulb output already outstrips Halogen and matches HID.
Car LED bulbs are now reaching the market.
They are already available in both single and dual beam format.
I expect them to progress quickly to triple format (Main/Dip/DLR).
The dual beam format uses a single reflector with separately positioned light chips for Main and for Dip.
Power consumption of these LED bulbs is around one fifth that needed to run a Halogen bulb.

John

At the opposite end of the spectrum in my experience blue bulbs are useless.

Peter

Anyone swapped hid for led and can review the differences.

Anyone swapped hid for led and can review the differences.