The Seven Cities of Gold, the Fountain of Youth, and Headlamp Lens Restoration

[fyrstormer]

Another engineering axiom from yours truly: "Nothing that plugs in and turns on ever goes on sale unless it's obsolete or defective." Headlights plug in and turn on, so this rule applies to headlights just as well as laptops and cellphones. Since headlights don't become obsolete until the car they're intended for has reached "antique" status, the conclusion regarding discount headlights is both obvious and accurate.

 

[bshanahan14rulz]

fyrstormer is our philosopher trapped in an engineer's mind ;-)

 

[-Virgil-]

Another engineering axiom from yours truly: "Nothing that plugs in and turns on ever goes on sale unless it's obsolete or defective." Headlights plug in and turn on, so this rule applies to headlights just as well as laptops and cellphones. Since headlights don't become obsolete until the car they're intended for has reached "antique" status, the conclusion regarding discount headlights is both obvious and accurate.

Actually, have you seen what happens to prices for headlamps that are no longer made? Sure, demand goes down as the population of the vehicle declines, but prices go way up. Some of the half-Italian/half-American cars come to mind (Cadillac Allanté, Chrysler/Maserati TC) and I'm sure there are plenty of others. I would be drawn and quartered by the styling department of every automaker in the world if they heard me, but I think there's a lot to be said for standard sizes and shapes for headlamps, so no matter what the technology of the day is, you can still get headlamps for your vehicle no matter when it was made, or where.

 

[bshanahan14rulz]

I've always thought that companies with good projectors should just use those in all their cars. I guess the savings in the higher quantities doesn't quite balance it out enough to keep their product lineup pricing where they want it. Always thought Koito did good work, but their best designs are limited to one model of car per model of projector. Just saw Kia is making a car with LED headlamps. Hmm, I should stop rambling.

 

[-Virgil-]

"Good projectors"...what do we mean by "good"? Whose definition of "good" are we using? Yours, mine, Consumer Reports'? If I'm an automaker and I'm trying to pick a projector, I will probably factor in price, Consumer Reports' test protocol, warranty matters (bulb type longevity), mounting height, benchmark vehicles, feedback from focus groups and existing customers, personal preferences of whoever is in charge of my lighting department, price, price, and price. And also warranty matters; one US automaker tried European-type low beams in their US-market cars for a short time and then reverted to American-type lamps because buyers were taking their cars back to the dealer for "wrong headlight aim" because they thought the lower/left side of the low beam cutoff was the left headlamp and the upper/right side of the cutoff was the right headlamp and the two of them weren't aligned. So now that automaker uses a straight-line cutoff with no step-up or ramp-up and the customers don't complain about "wrong headlight aim" any more.

 

[bshanahan14rulz]

Yep, I guess my last line said it all. I didn't take into account how much more work it would be to ensure that the lamps were always at the same height regardless of vehicle, and of course the big ol' bottom line. A projector with a compliant pattern at one height might be at a lower height on a different car and the pattern projected onto the road would have a skewed distribution with way too much lux up close and not enough out far, not to even mention the test points being out of bounds. I guess that's why we leave headlamp engineering to the headlamp engineers

 

[Alaric Darconville]

"Good projectors"...what do we mean by "good"? Whose definition of "good" are we using?

My definition of "good" would include "no plastic lenses"; even if the photometrics otherwise completely *ROCKED*, they'd not rock for long depending on the plastic.

 

[fyrstormer]

fyrstormer is our philosopher trapped in an engineer's mind ;-)

Yep. I even aced philosophy in college. Some professors like it when you debate them constantly.

 

[fyrstormer]

Actually, have you seen what happens to prices for headlamps that are no longer made? Sure, demand goes down as the population of the vehicle declines, but prices go way up. Some of the half-Italian/half-American cars come to mind (Cadillac Allanté, Chrysler/Maserati TC) and I'm sure there are plenty of others. I would be drawn and quartered by the styling department of every automaker in the world if they heard me, but I think there's a lot to be said for standard sizes and shapes for headlamps, so no matter what the technology of the day is, you can still get headlamps for your vehicle no matter when it was made, or where.

Hey, I never said prices on obsolete equipment were required to decrease.

Generally speaking I agree about the benefits of standards, but as a compromise to keep cars looking sleek like they do now, I'd settle for at least using headlight assemblies that never wear out under normal circumstances. Of course, that would require switching back to glass.

 

[fyrstormer]

I've always thought that companies with good projectors should just use those in all their cars.

Ignoring for a moment the subjectiveness of "good", I have to say my new car has HID projector lowbeams and they're so good I almost never use the highbeams. The beam pattern is flawless and the brightness is so good I can see well in any weather. The only time I ever use my highbeams anymore is when I'm driving in the woods and I need to see the path the road is taking through the trees.

 

[-Virgil-]

my new car has HID projector lowbeams and they're so good I almost never use the highbeams.

That is an unfortunate and dangerous (and common) error. Use your high beams whenever there is no vehicle in front of you; no matter how good you feel your low beams are, they are still geometrically limited in their distance range.

 

[fyrstormer]

That is an unfortunate and dangerous (and common) error. Use your high beams whenever there is no vehicle in front of you; no matter how good you feel your low beams are, they are still geometrically limited in their distance range.

I can't agree with that rule.

I know perfectly well that the lowbeams are limited in range; that's the point of their existence. They are nice and bright, and they have a sharp cutoff so I know exactly how far in front of me I can see. That means there is no guessing about whether I'm overdriving my headlights. If I'm uncomfortable with how far I can see with only my lowbeams, I turn my highbeams on. However, the highbeams on my car are ONLY good for distance, and barely touch the road at all, so unless I NEED to see far in front of me, there is no benefit to using the highbeams.

Where I live the highways are largely lit by overhead lights, and the back roads often don't have long-enough straightaways for the highbeams to be of any use. On an overhead-lit highway, I can already see as far as I want, and on a twisty back road, turning on my highbeams does nothing except ruin my night vision and instantly blind other drivers coming around corners.

 

[Alaric Darconville]

That is an unfortunate and dangerous (and common) error. Use your high beams whenever there is no vehicle in front of you; no matter how good you feel your low beams are, they are still geometrically limited in their distance range.

I can't agree with that rule.

I know perfectly well that the lowbeams are limited in range; that's the point of their existence. They are nice and bright, and they have a sharp cutoff so I know exactly how far in front of me I can see. That means there is no guessing about whether I'm overdriving my headlights. If I'm uncomfortable with how far I can see with only my lowbeams, I turn my highbeams on.

You might be 'feeling comfortable' with how far you can see with only your low beams long after you've overdriven them. Low beams are good for 45mph, maybe a bit faster, but not much faster. You're tricking yourself with how good your low beams seem to be to you (even if they are objectively excellent).

However, the highbeams on my car are ONLY good for distance, and barely touch the road at all, so unless I NEED to see far in front of me, there is no benefit to using the highbeams.

But there is. At 60mph, you're going 88fps, and you need more than two seconds' seeing distance in front of you. The low beams aren't going to do that for you.

on a twisty back road, turning on my highbeams does nothing except ruin my night vision and instantly blind other drivers coming around corners.

They won't ruin your night vision, because they're not saturating the foreground with light. Also: You can see other drivers' headlamp beams before you see their cars; dim your lights before you see their cars. (Another trick I use is to dim my lights when I see the clearance lights of a semi appear over the hill, as those appear just before the windshield does. Passenger cars aren't so lucky.)

 

[NFT5]

You might be 'feeling comfortable' with how far you can see with only your low beams long after you've overdriven them. Low beams are good for 45mph, maybe a bit faster, but not much faster. You're tricking yourself with how good your low beams seem to be to you (even if they are objectively excellent).


But there is. At 60mph, you're going 88fps, and you need more than two seconds' seeing distance in front of you. The low beams aren't going to do that for you.

My headlights are 1.08m from ground to centre of light. They're declined at the factory specified setting of 1.2% giving me about 83m to the point where the horizontal part of the cutoff touches the ground on level road. 88fps is about 27m/s so, in theory I have a shade over 3 seconds light on the road at around 100km/h. In fact, there's more than this because they're ECE spec lights and the slope on the left (passenger) side extends visibility further (at least to the left of the centre of the road). The lights do produce some output above the cutoff line so it's not completely black, and there is some reflection as well.

This vehicle is a 4 wheel drive but on other vehicles I've had I've always set the aim for about the same distance.

I would have thought that if your lights are only giving 2 seconds distance then they're probably set a little too low.

 

[fyrstormer]

You might be 'feeling comfortable' with how far you can see with only your low beams long after you've overdriven them. Low beams are good for 45mph, maybe a bit faster, but not much faster. You're tricking yourself with how good your low beams seem to be to you (even if they are objectively excellent).

You assume I'm tricking myself with how good my low beams are. I take driving very seriously; when I drive, there are no distractions -- I don't even turn on the radio unless I'm on an Interstate. When passengers talk to me, my responses are slow and halting, because I'm "distracted" from the conversation by my focus on driving. Where I live, deer (and immigrant workers) casually walk across the road at their convenience; I know quite well that I need to see them before I can avoid them.

They won't ruin your night vision, because they're not saturating the foreground with light. Also: You can see other drivers' headlamp beams before you see their cars; dim your lights before you see their cars. (Another trick I use is to dim my lights when I see the clearance lights of a semi appear over the hill, as those appear just before the windshield does. Passenger cars aren't so lucky.)

I wasn't referring to coming over a hill and encountering oncoming traffic, I was referring to coming around a blind curve and encountering oncoming traffic. I would never see the other car's headlights in that scenario because the forward-scatter from their headlights would be washed out by my highbeams. I know this from experience.

I live on the east coast, where the back roads are twisty and the suburbs are often heavily wooded. (even in densely-populated areas there are main roads that cut through the woods between developed areas.) Yes, there are plenty of times when I have to turn off my highbeams because the backscatter off the trees is hurting my eyes and making it harder to see far away.

Fun fact: several optometrists have confirmed that they didn't need to dilate my pupils to examine my retinas properly, because my pupils are naturally larger than normal.

 

[-Virgil-]

My headlights are 1.08m from ground to centre of light. They're declined at the factory specified setting of 1.2%

What kind of vehicle is this, and where are you finding that 1.2% spec? That's a pretty high headlamp height.

giving me about 83m to the point where the horizontal part of the cutoff touches the ground on level road

My math comes up with just shy of 90m. That's a very long low beam distance, relatively speaking, for an ECE type low beam. However, low beams -- however good they are -- do not substitute for high beams.

You assume I'm tricking myself with how good my low beams are.

It's not really a matter of tricking or fooling yourself. It's that the human seeing system isn't a very accurate judge of its real performance. You feel you can see adequately, but in fact you really can't under the driving conditions you describe.

 

[NFT5]

What kind of vehicle is this, and where are you finding that 1.2% spec? That's a pretty high headlamp height.


My math comes up with just shy of 90m. That's a very long low beam distance, relatively speaking, for an ECE type low beam. However, low beams -- however good they are -- do not substitute for high beams.

This:

Mitsubishi Triton, seen here with the little wheels and tyres.

There is a low beam symbol and "1.2%" moulded into one of the attachment arms on the top of the headlight.

No, I wasn't suggesting that low beams substitute for highs. I use highs, and more, whenever conditions/traffic allow. When approaching vehicles can be seen at 5km it's courteous to drop to low beam and that means a long time before passing. Having good low beams is critical, as is having them aimed as high as is permitted. Generally I find that I can comfortably see out to the limit of the lit area but 90m is no substitute for 900m and being able to light up both sides of the road.

In a standard sedan/wagon I still like to have the low beams out to a similar distance. It's not easy to aim them at that distance but I have a headlight aimer in the shop so no problem to get them accurate. The ECE standard does allow 1.0-1.5% declination in initial aiming and a limit as low as 0.5% with the horizontal part of the beam on the road between 50m and 100m so I'm towards the outer limit but still within the standard. A nice, comfortable place to be, IMO.

I'd be very concerned driving a vehicle which had, as Alaric suggested, lights which gave only 2 seconds range and an effective speed limit of around 70km/h. Is there not room within the DOT/SAE aiming standards to wind them up a little more?

Oh, and your maths :laughing::laughing: is correct. It was 1.30am when I typed that last post.

 

[Alaric Darconville]

No, I wasn't suggesting that low beams substitute for highs. I use highs, and more, whenever conditions/traffic allow. When approaching vehicles can be seen at 5km it's courteous to drop to low beam and that means a long time before passing.

You dip your beams when oncoming traffic is 5 kilometers away? That's about 25x sooner than you really need to by law; but I can certainly grant dipping them a little sooner.

Having good low beams is critical, as is having them aimed as high as is permitted. Generally I find that I can comfortably see out to the limit of the lit area but 90m is no substitute for 900m and being able to light up both sides of the road.

Having enough light to see that well nearly a kilometer away possibly means too much foreground light. Yes, we all like to see farther at night, but nighttime driving calls for different tactics from just having flamethrowers on the front. As you undoubtably know, many animals travel at night as in desert areas it's much cooler. I know that on my car there can never be enough light after a certain speed, because of the braking performance of the vehicle, reaction time, and such.

I'm not sure how accurate website "Car Stopping Distance Calculators" are, but I found one that was interesting.

From 80km/h (50mph):
Thinking distance: 15 meters (49 feet). Braking distance: 38 meters (123 feet). Total stopping distance: 53 meters (172 feet).
From 90km/h: 17, 48, 64. (56mph: 55, 156, 211)
From 100km/h: 19, 59, 77. (62mph: 61, 193, 254)
From 110km/h: 21, 71, 92. (68mph: 67, 233, 301)
From 120km/h: 22, 85, 107 (75mph: 73, 278, 351)

The reaction time is linear; the actual braking distance is proportional to the square of the speed.

In a standard sedan/wagon I still like to have the low beams out to a similar distance. It's not easy to aim them at that distance but I have a headlight aimer in the shop so no problem to get them accurate. The ECE standard does allow 1.0-1.5% declination in initial aiming and a limit as low as 0.5% with the horizontal part of the beam on the road between 50m and 100m so I'm towards the outer limit but still within the standard. A nice, comfortable place to be, IMO.

The range of declination below the optical axis is based on the headlamp height, under ADR (if I'm reading this correctly. Yes, I know that's for the Northern Territory; I've been looking for a similar thing in the ACT, but haven't, yet).

I'd be very concerned driving a vehicle which had, as Alaric suggested, lights which gave only 2 seconds range and an effective speed limit of around 70km/h. Is there not room within the DOT/SAE aiming standards to wind them up a little more?

One can only aim them up so high until glare becomes a problem for other traffic.

Pretty sharp-looking vehicle. I see you've got an intake snorkel-- did you also snorkel the exhaust? My brother told me about a guy showing off his Suburban's new snorkel by driving in deep water, and the water pressure plugged the exhaust. Oops

Also, not to pick on you about your Lightfarce lamps, but you do plan on replacing them with something better eventually, right?

 

[-Virgil-]

Whoah...it's not correct to drop from high to low beam as soon as you can see an oncoming car 5km away. Laws vary by jurisdiction (state, province, territory, etc.); here is the situation in North America:

The US National Highway Traffic Safety Administration (Federal DOT) and its Canadian equivalent Transport Canada, can alter headlamp technical specifications but cannot alter state/provincial use-of-lights regulations, nor can those national agencies compell state/provincial lawmakers to change the rules regarding dimming distances. Every US state and every Canadian province has its own laws regarding when you must dim to low beams in terms of distance to a leading or oncoming vehicle. These were set before the maximum allowable high beam intensity (regulated at the Federal/national level) was doubled in 1978. When that happened, the dimming distances to prevent dazzling oncoming and leading motorists should have been increased. Most states have 500 foot/152m (oncoming car), 200 foot/61m (leading car) dimming distances specified in their laws. Because the illumination at the eye is proportional to the lamp's intensity and inversely proportional to the square of the distance, a solid estimate can be made for how dimming laws should have been changed. If 500/200 feet were deemed to be acceptable for the pre-1978 headlamps, then for the strongest 1978-up headlamps the dimming distances should have been changed to 700/280 feet (213/85m), and for today's highest-intensity ECE high beams the dipping distances should be 970/390 feet (296/119m).

So by all means look up your local dimming law, but it's a fairly safe bet the Australian state requirements are roughly comparable to the US and Canadian regional requirements, so even if you take a super-cautious approach and dim at 300m for an oncoming vehicle or 120m for a leading vehicle, you will be well within the law and much, much safer than your current practice.

 

[Alaric Darconville]

Whoah...it's not correct to drop from high to low beam as soon as you can see an oncoming car 5km away. Laws vary by jurisdiction (state, province, territory, etc.)

So by all means look up your local dimming law, but it's a fairly safe bet the Australian state requirements are roughly comparable to the US and Canadian regional requirements, so even if you take a super-cautious approach and dim at 300m for an oncoming vehicle or 120m for a leading vehicle, you will be well within the law and much, much safer than your current practice.

From ACT Road Rules Handbook:
Points for night driving:
• You can use high beam on any road or street, however, when using high beam you must dip your lights for oncoming
vehicles as soon as possible and at least 200 metres away.

Of course, 5Km is *at least* 200m away, but that's not within the (from a legal standpoint, fictitious) "Spirit of the Law". 200m? Fine. 250m or 300m? Probably still fine. 600m? Most likely waaaay too soon, endangering yourself.

And, yes, the "inverse square law" comes into play when determining beam dimming distances- but it also comes to play in terms of how much excessive foreground light you'll get from a low beam that is able to hit the road surface as far out as you want it to with the intensity you want.