Some people do seem to think that they are rain lights. In particular there was a bloke who was trapped in the middle lane on the M1 on Saturday night, hehad his front and rear fog lights on and went as fast as he could without leaving the middle lane. After overtaking him four or five times, the next time he passed me I sat behind and flashed my lights until he finally got the message.

Yes it was dark, yes it was raining but you could see for bloody miles!

Then two minutes later there was another one on the M69 grrrrrr.

After a quick trundle through Wikipedia, only to fail to find the human factors data I needed...Fog lights are designed to produce a broad, flat, short beam, whereas headlights produce a narrower, taller, and much longer beam. You can verify this for yourself by stopping on a quiet unlit road tonight, and dropping onto sidelights. Now turn the dipped headlights back on, and note the furthest point you can see reflecting the headlights. Now drop back onto sidelights, and turn the fogs on. See just how much shorter the reflective range is? That's why fos work to reduce reflective glare in dense fog. Now turn the dipped beam back on again, and look for the furthest you can actually see a reflection from again. Is it honestly even as far as when you were on dipped headlights alone? I'll be surprised if it is.

Dont fogs also kick upwards? Hence the dazzle, as fog is almost non existant next to the ground.

Most of the light from fogs goes down or straight, not up; it's a question of lens design.

When I'm driving on unlit roads I usually put the front fogs on. They don't dazzle anyone and I want as much light as possible on the road ahead!

OH YES THEY DO!!! which is why they are only legal when visibility is reduced to less than 100 metres BY FOG OR FALLING SNOW.One reason for the confusion is that when I was a lad fog lights were designed to provide a low spread of light just in front of the car because even dipped headlamps ion those days reflected back off the fog at you.Now with improved dipped headlight cutoffs, front foglights are simply high intensity lights so other drivers can see you easier in thick fog just like the rears.A couple of years ago our local police were stopping drivers to tell them to turn them off but I think they've stopped now.

I could add the stupid LED lights that a lot of German cars are using now, they're very dazzling as soon as the light levels go down,.

Edited 25 November, 200916 yr by Calomax
Typos

I disagree Calomax. I've never been dazzled by someone else front fogs. If I had, I wouldn't use mine. I have been dazzled by these relatively new, projector style lights though. Whether xenon or halogen they do seem exceptionally bright.

I partially disagree with Calomax too, but because my front fogs don't have the range my dipped heads do, and cause much less reflection in night-time fog.

Fog lights do tend to dazzle though I have to allow that some do not. It probably a question of adjustment and poor lens design. I agree with the post above that mentions that headlamps have improved with less unintentional stray light above the beam cut off while on dipped beam. Some light is deliberately allowed over the cut off however even on the very best headlamp dipped beams to facilitate sign post reading and a greater degree proprioception with better spacial awareness. While the general intention of fog lights is for a flat broad span of light with a sharp flat cut off, the majority of fog lights are cheap small units that that do not achieve the tightest of beam control and so allow unintentional light scatter above the beam cut off. This coupled with he the flimsy under bumper mountings which are far too low for every day use allows the aim of the beam to point above the horizon causing dazzle. Correctly adjusted fog lights mounted at under bonnet hight should not allow the cut off to project very far, its a matter of geometry but because may fog lamps mounted so low they are usually incorrectly aimed to achieve greater throw, the cut off projects further and above the horizontal and causes dazzle.

The best fog lamps are large expensive rally type units Cibie' & Hella possibly Bosh also. They have quality lenses and reflectors with a much more intentional beam with closer tolerances. The light output is incredible. The best position for them to be used for dipped beam assist, is ideally above bumper, with the cut off aimed just below the horizontal. These specialist units mounted in this way cause minimal light scatter but are still illegal to use outside of the stated conditions.

Lighting regulations are not just found in GB but agreements exist throughout the EU. Their are other reasons why fog lights are not considered legal for use outside of the conditions of fog and falling snow and that is to do with vehicle recognition.

Vehicles are not permitted to display more than two lights of certain luminosity when on dipped beam and this has been the case for about a hundred years. Police have initiatives every now and then, they have purges, all of a sudden car drivers are targeted who inappropriately use fog lights and their are spates of prosecutions up and down the country every year.

Agreed that some foglights don't dazzle as much as others but most do. I think it's purely down to the intensity of the bulb. I had a mark one Fiat Punto and didn't realise I shouldn't use them so i did, and i was constantly being flashed and eventually a driver in front at traffic signals told me in no uncertain terms what effect I was having in his mirrors.

Some of the worst are the huge ones on some Subarus and many of their drivers are amongst the worst offenders.

I'll continue to flash the ones I'm dazzled by and I know I shouldn't.

The intensity of the bulb is more or less the same with most Fog lamps or any other auxiliary lamp come to that all being 55W unless it is of advanced design and using a 35W HID Xenon. That is the same as a dipped beam bulb but no one here is saying that they are too bright, though some are of these are aimed in a very poor way. It might some times be possible to find E' marked 100W bulbs but I very much doubt that the majority of fog light users fit them. It is down to the design of the reflector the lenses and accuracy of aim. If all 3 of these are up to scratch then their would be less of a problem with glare but still a problem with legality. On empty roads their is less of a problem with glare obviously. If people do use them they should turn them off when approaching other road users just like they would with main beam or other auxiliary lights because of the danger of dazzle and discomfort to other road users. I can only presume that it is partly due to ignorance, laziness or in some way selfishness that people do not do this. If anyone is using them because they cannot see the road well enough when in the vicinity of other vehicles, then a suggestion might be to slow down to a safer speed or have their headlamps changed for new ones. Headlamps do deteriorate with age and new ones do make a difference. If anyone was using fog lights at the time of an accident and their was no legal reason for ding so then this cold be used against them in any litigation, aside from any prosecution that he police might possibly bring.

Its about bloody time manufacturers invented auto-fogs that detected when visibility was poor. Making them so you cant overide them would be good too. When are people going to realise they don't look cool with fogs on, they just annoy the hell out of people.

My Mazda has auto lights (which work brilliantly), and fogs can be selected in auto just fine

Its about bloody time manufacturers invented auto-fogs that detected when visibility was poor. Making them so you cant overide them would be good too. When are people going to realise they don't look cool with fogs on, they just annoy the hell out of people.

My Mazda has auto lights (which work brilliantly), and fogs can be selected in auto just fine

I would never buy a car that took light control away from me.

Just because people think fogs and sides are bad, doesn't mean there are not times when that is the best to drive with. It''s very rare and only in very thick fog, but if you take my control of the lighting from em, I don't buy your car. End of.

If people do use them they should turn them off when approaching other road users just like they would with main beam or other auxiliary lights because of the danger of dazzle and discomfort to other road users. I can only presume that it is partly due to ignorance, laziness or in some way selfishness that people do not do this.

Over here I think a lot of people use them because they are there and the think they look good. Also maybe they want to show that they've bought an "Up-Market" car.

Incidentally, someone has started another thread on the same subject.

Over here I think a lot of people use them because they are there and the think they look good. Also maybe they want to show that they've bought an "Up-Market" car.Incidentally, someone has started another thread on the same subject.

OTOH I see them and think the message is "look at me; I am so stupid I can't use a light switch properly!"