improving light output for 1999 T&C?

[article on Super-Lite]

It is not common. Also very difficult to mount properly in a vehicle other than a '69-'70 C-body Dodge.

Best illustrated by the article in question, which I may be able to scan tonight.

Pick your beam units carefully and you won't need an aux low beam:

DS

Not speaking for Dan, who can surely be more specific, it seems to me to just be a characteristic of the overall quality and level of design of the headlamp optics. Remember that most car companies don't build headlamp optics, its sub-contracted. Some BMWs have annoying beams, others do not. In fact I find later and current BMWs far less blinding than most others on the market, especially Honda/Acura and some Toyota/Lexus installations. One of the best on the road, to my eye, is the setup in the Cooper Mini (a BMW product). The color rendering of the burner used and the lack of chromatic aberration (blue flashes) from the optics is so good that they can easily be mistaken for non-HIDs at a glance.

My vote for the absolute WORST HID installation (as far as blinding oncoming drivers and being annoyingly blue from a lot of angles) is still the Honda S2000.

H'm. I haven't noticed any such thing. Which specific models do you find particularly offensive? All of BMW's current-production HID headlamps (and, come to think of it, all the ones they've ever used in the US market) have very good beam pattern control with a sharp cutoff. Some of the headlamp units have styling elements that can worsen glare and upward stray light, such as chrome masks, bezels or surrounds between the optic lens and the aero front cover lens. And some (current 5-series) do have a more intense visual signature than others (X5 SUV) due to the construction details of the optic lens. Also, projector lamps, due to their smaller illuminated surface, generally have more intense visual signatures than reflector lamps with larger illuminated surfaces, given the same light source. I think there's nothing special about BMWs, more likely what's at work is the inherently ~50% more glaring nature of the light from automotive HIDs and typical lack of headlamp aiming in North America.

I think the most glaring factory HIDs on the road (not counting the illegal "retrofits") are from the new full-size Range Rover.

DS

Yeah, well, Condemner Retards thinks the way to create a less-glaring low beam is to eliminate the sharp cutoff, so...

DS

(Hmm, how come that doesn't appear to be linked to from your main lighting site, or did I just never find said link?)

At any rate--I see that the complex-reflector Cibie units seem to have a hot spot that's higher than the sealed beams--wouldn't this give _greater_ distance vision? (I assume that the Philips sealed beams represent about the best of their class?)

I don't see any data for the non-complex reflector Cibie offerings--would they, using maybe the "classic" look clear lenses, still be an upgrade over DOT sealed beams?

With that, I'll save any other possible questions regarding the subject until I read the Super-Lite article.

--Aardwolf.

Because it isn't, yet. Major site revisions and an ISP change are in progress.

Yes. The closer to the headlamp axis (straight ahead of the bulb) the hot spot is placed, in both the horizontal and vertical directions, the longer will be the beam reach, for a given aim angle.

Just about. Next time I'm in Ann Arbor I need to remember to stop in at UMTRI and pick up a bunch of sealed beam scans, and I should have some scans of selected halogen sealed beams within a few months.

I have it for 7" rounds, so far. 5.75" will come later. See below.

While the answer depends on the specific situation, generally speaking, in my opinion, and I'm certainly not alone, yes.

Here are photometric ("light tunnel") data for the Cibie 7" round and the Hella 7" round H4 E-code headlamp in low beam mode. Same bulb, same power supply, same light tunnel.

If you're not familiar with isocandela diagrams, these will look like random squiggles and lines. Think of it as a topographic or "contour" map of the correctly-aimed beam pattern. Each differently-colored line represents the threshold of a particular intensity level, with the color legend located to the right of the isocandela diagram. The diagram is plotted on a chart calibrated in degrees. Straight ahead is represented by (0,0), that is, zero degrees up-down and zero degrees left-right.

To get a mental approximation of the units and amounts under discussion here:

Parking lamp: About 60 to 100 candela Front turn signal: About 500 candela Glaring high-beam Daytime Running Lamps (e.g. Saturn): About 8000 cd.

Things to notice about these two diagrams:

(1) The Cibie produces a much wider beam pattern than the Hella. The 1000 candela line of the Cibie's beam pattern extends from 25 degrees Left to

25 degrees right, while the 1000 candela line of the Hella extends from 18 degrees Left to 20 degrees Right. At a distance of 50 feet from the car, this means the 1000 candela-and-brighter portion of the Hella's beam is 10.5 feet narrower than that of the Cibie. The 300 cd contour of the Cibie's pattern is *far* wider, extending from 43 degrees Left to 50 degrees Right, compared to 26 Left to 25 Right for the Hella. This means the overall useful width of the beam pattern at 25 feet from the car, as perceived by the driver, will be 40.7 feet for the Cibie and 22.3 feet for the Hella.

2) The total luminous flux (overall amount of light) within the beam pattern is 695 lumens for the Cibie, 463 lumens for the Hella - the Cibie is 50.1% more efficient. (the TLF data is listed as "Luminous Flux" in the readings up above the isocandela diagram)

The high beams for these two lamps (isocandela diagrams not yet scanned in) are very similar in overall performance and amount of light -- the critical difference is that the Cibie's high beam hot spot is located closer to (0,0) and closer to its low beam hot spot. The Hella's high beam and low beam hot spots are separated by a fairly large vertical amount, such that setting the lows where they belong results in most of the high beam light going up in the trees, but pulling the high beams down so they send light straight ahead puts the low beams 10 feet in front of the car.

As always, I welcome whatever lighting questions anyone might have. I answer 'em with facts and data, though, not with hype and pseudoscience, so folks who are looking for reassurance that their new Hyper Zenon Arc Xtreme Stupidwhite Bloo-Wite Silvermax Plazma Kewl Diamond 5000K MetalGlow lights are really good...aren't gonna get it.

DS

Factory info poster on the '69-'70 Dodge Super-Lite, which is better than the article I was going to scan in, is here:

DS

Well that would explain things.

Jeez, well that shuts me up! Real, extensively detailed data. On newsgroups even. (Sounds like one mother of a site overhaul.)

Thanks for the the explanation. I'm however not familiar with the difference between isocandela, candela, candlepower, and lumens.

I see now why you prefer the Cibie offerings and don't have that high an opinion of the Hellas--it ain't just the sharpness of the cutoff. Chalk one up to the French, I guess.

That sounds quite subpar--and they must still meet the relevant codes. Don't people, like, _notice_?

Well as someone who is involved with the sciences myself, I quite appreciate that, anywhere I find it. I've archived quite a few of your replies to various posts--I know you've told people to ask a lot of questions, but at least I'll not be asking the same ones more than once. I am curently juggling a few expenses and trying to plan exactly what to do regarding lighting upgrades that I've mooted at some length over this newsgroup, I should have it decided rather soon; I certainly find your input on the matter helpful. And rational. Which is kind of the same thing in my book.

Oh yeah--if you don't mind a couple other questions,

--What is an R2 bulb exactly? (They seem to have been used in old Hella and Bosch/Eisman warning lights.)

--Are H1 low beams generally a better use for 5.75" rounds than H4 high/low, what with reflector size?

--How come there don't seem to be any H2 low beams, are they somehow better suited to driving light pencil/flood beams?

--What do the optics look like on Cibie's H4 combination fog/driving lights--is the narrow center "slit" in the lens/reflector for the driving light or fog beam?

--What is the deal with Lucas Flamethrowers, performance/bulb wise--and do you know offhand when they were introduced?

OKAY, that just about scrapes the bottom of the barrel for historical/esoteric lighting questions that I have at this time.

As I said before, for anything else (if necessary) I'll wait for the article.

--Aardwolf.

An iso diagram is just a plot of degree. A topo map of a mountain is an isoelevation diagram; each isoline indicates a particular elevation. In an isodepth diagram of the ocean, each isoline indicates a particular depth. In an isocandela diagram of a headlamp beam, each isoline indicates a particular level of intensity.

Steradian (sr): Solid angle subtending on the surface of a sphere an area equal to the square of the sphere radius "r". The surface has total area

4(pi)r, or 12.57r, and the sphere contains 12.57 steradians.

Candela (cd): Non-metric unit of luminous intensity equal to one lumen per steradian. In North America, headlamp beam performance is expressed in candela.

Lux (lx): unit of illuminance. One lux is one lumen per square centimeter. In Europe, headlamp beam performance is expressed in lux.

Lumen (lm): The luminous flux from a uniform point source in a solid angle of one steradian. Used to express the output of light sources ("bulbs") outside North America. To get lumens from MSCP, multiply MSCP by 12.57.

[Mean Spherical] Candlepower (mscp): The luminous flux from a uniform point source emitted in all directions (spherically). To get MSCP from lumens, divide lumens by 12.57. MSCP is used to express the output of light sources ("bulbs") in North America.

Lumens Per Watt (lpw): The measure of light source efficacy. How much light comes out (lumens) for each unit of electricity (watt) put in?

Cheese, wine and headlamps make strange bedfellows, but this is the shortlist of things the French do well.

They do.

Some people notice right away. Some people have to be told what the problem is before they'll say "Oh yeah...I knew there was something wrong, just couldn't quite place it".

This vertical separation actually has a use. Headlamps like this work well in high-mount situations. ECE low beams' aim is mount height dependent; the higher the headlamps are mounted the lower they're aimed.

It is a tungsten (non-halogen) dual-filament headlamp high/low beam bulb having a 165-degree geometric arc's worth of shielding under the low beam filament to create a cutoff as required by the European low beam pattern spec, introduced in 1955. The bottom 40 percent of the reflector area is not used on low beam, its "view" of the low beam filament being blocked by this shield. The filament geometry and placement is identical to the later, higher-output halogen H4 introduced in 1971, though the base is different. Therefore, H4 burners on R2 bases work perfectly in any lamp designed for an R2. Several of the major makers no longer make tungsten R2s, having switched to a halogen 45/40W burner on the R2 base.

It totally depends on the type of optic in use. There are many H1 low beams that have a 165-degree arc's worth of mechanical filament shielding built into the headlamp. In this case, the bottom 40% of the reflector is still not used, just as with H4. H1 does produce more light than the H4 low beam filament (1500 lumens vs. 1000 lumens, nominal), but overall beam robustness ("HOw much light is in the beam?") and formation ("...and where's that light sent?") are more important factors than the bulb type in what is "better". Then again, there are lamps like the Cibie CSR or the Hella BiFocus that reduce (BiFocus) or eliminate (CSR) the occlusion-type shielding and use more (BiFocus) or all (CSR) of the reflector area. These are considerably more efficient. Given amount of light available from the light source, greater active reflector area means more light collected, therefore available for the beam. BiFocus and CSR beams are more efficient

*and* more effective than H4 or shielded-H1 designs, but more efficient headlamps are not necessarily better ones. All DOT sealed beams use the whole reflector area for low and high beam, for instance...

H2 is a very high efficacy bulb. 55 Watts, 1820 lumens. However, it is a tricky bulb to work with from a mechanical standpoint. You have to have a special "bulb holder" to adapt the bulb to the optic unit, and these are expensive to make and a nuisance to assemble and service. Also, its lifespan is comparatively short. For that reason, it is no longer widely used and has in fact been withdrawn from ECE R37 (i.e., no longer on the list of approved light sources for new lamp designs). Other similarly-performing bulbs with longer life and less bitchy mechanical requirements are now preferred.

Not sure what kind of answer you're looking for here. Buy a set and see for yourself! ;^{)}

Doesn't make sense to me, show me a picture of what you're asking about. Upper 60 percent of lens is for fog beam and is also used for drive beam, lower 40 percent is exclusively for drive beam. This lamp is basically a modified high/low beam H4 headlamp. Instead of producing a low beam with a hot spot, upstep or upsweep to the right (Or left, for LH-traffic countries), the "low beam" is a symmetrical, wide bar of light with a straight-across cutoff. High beam = Drive beam.

It's very easy to make a driving beam (=high beam) or spot beam (=tight high beam) or flood beam (=wide high beam), because no particular beam control is necessary. Stick a filament at the focal point of a parabolic reflector, and you're done. Therefore, even the Prince of Darkness could do it with some success. Nowtimes, there are *much* better lamps, though perhaps none with so cool a name.

Articles seldom get written until there's a demand for them, so pipe up.

DS

That's what I meant by "wait for the article". I hadn't looked for it yet but I will now.

Re: Isocandela--that's what I get for reading stuff so late at night--of course it refers to the diagram--as would isotherm, isochron, isobar, etc. Should have realized that.

--Aardwolf.

Cibie CSRs are the best headlamps I've ever used. Period.

I was thinking about those things the other day. Where was the switch located? I thought possibly where the wagon rear window switch went, but I do remember looking at Dodge wagons that had them that year. (but I do not remember where the switch was)

Thanks.