E-code versus Dot OEM Light

[moribundman]

Vehicle: my '96 Audi A4
Location: parking lot
Time: one hour after sunset (two different days)
Position of the car was identical on both days
Camera position and angle were identical (at least very close)
Shot on film (Fuji 800 ASA), exposure was manually set and identical
The second picture has no "cones" (cans), because it was too windy
The distance to the island with curb clearly visible straight ahead was 50 meters (164 feet).



Picture 1: OEM Bosch DOT headlights, US import version ('96 version)
- Osram H7 55 W low beam
- free form reflector (no projector) lights
- plastic lens
- integrated headlight aiming aid (bubble level), set according to specs ("level," no dip)

Picture 2: OEM Bosch e-code headlights ('96 version)
- Osram H7 55 W low beam
- free form reflector (no projector) lights
- glass fresnel lens
- aimed according to specs (1.5% dip)

I have marked curbs and a reflective traffic sign with red arrowheads.
I don't think I have to comment on the obvious differences between the beam patterns.

 

[XB70]

E-codes for everyone!

 

[G-MAN]

Quote:

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Picture 1: OEM Bosch DOT headlights, US import version ('96 version)
- Osram H7 55 W low beam
- free form reflector (no projector) lights
- plastic lens
- integrated headlight aiming aid (bubble level), set according to specs ("level," no dip)

Picture 2: OEM Bosch e-code headlights ('96 version)
- Osram H7 55 W low beam
- free form reflector (no projector) lights
- glass fresnel lens
- aimed according to specs (1.5% dip)

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You've listed a free form reflector and a "fresnel" lens. If your lens is fluted, then you've just got a normal parabolic reflector. If your lens is plain clear glass/plastic, then you've got a free form reflector.

Cibie is currently the only company that I know of that is using both lens optics together with free form reflector optics to generate the beam patter on some of their aftermarket lights.

Your illustration is great, but I would offer one note: DOT beam patterns vary widely from lamp manufacturer to lamp manufacturer. In your case, it's clear that Bosch does a better job with the E-code version of their lamp than with the DOT version. There are DOT headlamps that would throw a much better pattern than your DOT lamps (and some much worse).

 

[moribundman]

G-MAN, I call both those lights free form reflector lights, because they both have reflectors with an asymmetrical complex shape and not a simple parabolic shape. Does that make them free form reflector lights? I think it does, but I do not know. The DOT and e-code version of these lights have identical reflectors, but while the DOT light has an almost clear lens with just some fresnel lens areas, the e-code has no clear area. I have no picture of the DOT lights, which I sold a long time ago, but here is one of the e-codes:

From the outside near the blinker to the to the inside near the grill:
- the low beam reflector has an inverted "L" shape
- the fog light reflector is the smaller reflector in the middle near the bottom
- the high beam reflector has also the shape of an inverted "L"

I never said or even implied that the DOT headlights on my car were the same, better or worse than, or even representative of any other DOT headlights (I had my lawyer help me phrase that). Of course there are differences between lights. My '84 Buick's sealed beams were just as bad as those Bosch DOT headlights. Should I have gone for an apples and oranges type comparison? I only wanted to demonstrate the differences between the OEM DOT and the OEM e-code headlights for the same model year and car -- which is what I did.

 

[G-MAN]

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G-MAN, I call both those lights free form reflector lights, because they both have reflectors with an asymmetrical complex shape and not a simple parabolic shape. Does that make them free form reflector lights?

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Are you saying that each of the hi and lo reflectors isn't a smooth parabola, albeit adjusted somewhat for the rectangular overall shape of the headlamp itself? If the reflectors have multiple separate reflector surfaces, then it's free form. If it has one asymmetrical smooth reflector surface, it isn't.

Here is the Cibie light that uses both:

Unlike the free form reflector on most modern clear lens headlights, this Cibie unit has over 50,000 individual reflector points on the reflector surface. You can read more about these lights at Daniel Stern's web site.

Here is a typical OEM free form headlamp:

As for my comment about your comparison, I was only trying to point out that not everyone with DOT headlamps will see the sort of improvement you did by going to E-Code (assuming they can go to E-Code).

 

[moribundman]

The reflectors have about these shapes (outline):

Each reflector has areas that are parabolic and others that are angular, generally transitioning smoothly from curved to angular. With and without the lens, the headlight produces the same basic beam pattern, but it is less even without the lens. The lens seems to fine tune the beam.

 

[G-MAN]

Quote:

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The reflectors have about these shapes (outline):

Each reflector has areas that are parabolic and others that are angular, generally transitioning smoothly from curved to angular. With and without the lens, the headlight produces the same basic beam pattern, but it is less even without the lens. The lens seems to fine tune the beam.

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Thanks for taking the time to illustrate your headlamps in that drawing. Since each individual lamp has its own reflector inside the overall housing, and these reflectors are more or less parabolic in nature, I wouldn't characterize your lamps as free form.

 

[moribundman]

I see elements of a free form and of a parabolic reflector. My manual does not state the type light beyond "Dreifachscheinwerfer" (triple headlight=low/high beam with integrated fog light).

By the way, the first car to have free form reflector headlights with clear lenses was the VW Passat 35i (B3 platform) in 1988.

 

[Jonny Z]

Wow!

The ECE had better spread in the foreground - and better down the road vision - something the DOT is supposed to excel in.

 

[G-MAN]

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Wow!

The ECE had better spread in the foreground - and better down the road vision - something the DOT is supposed to excel in.

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I don't think the DOT beam pattern is "supposed" to excel at anything.

Seriously, an E-code beam pattern is a well-defined pattern and is pretty much uniform from one lamp maker to the other. The same cannot be said for DOT compliant lamps. When it comes to DOT headlamps, you may get a fairly well-defined cutoff, good throw, and good lateral spread on one car (like with my 300M's std halogen lamps), or you may get a pattern that is actually worse than what we used to get with sealed beams (like my Olds minivan).

 

[moribundman]

By the way, my above pictures are from late 1996. To be frank, my Audi's e-codes are not any better than those of my 1989 VW Scirocco. Only the bulbs got better.

Current adaptive e-code lighting developments can be seen on this page: http://www.physik-am-auto.de/straopt/strahlenoptik_z2.htm
Sorry, it's in German, but if you look at the pictures you can glimpse what current developments are about to end up as standard features in production vehicles:

(3a) city light (extra wide)

(3b) turn light (extra wide in direction of turn, blinker-activated)

(3c) curve light (steering activated)

(3d) Autobahn light (1/3 more brightness and slightly increased range at speeds above 100 km/h)

(3e) bad weather light (modified beam to reduce glare and flare, wider beam, activated by use of wiper and/or rain sensor)

 

[Jonny Z]

Good luck getting this approved by DOT

Why are we always behind?

 

[Jonny Z]

Quote:

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...an E-code beam pattern is a well-defined pattern and is pretty much uniform from one lamp maker to the other.

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Isn't this the point of having a standard the first place?

 

[moribundman]

A low standard is also a standard.

 

[XB70]

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Here is the Cibie light that uses both:

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CSRs!

If I still had a car with 5.75" headlights, a set of CSRs would be on it.

CSR conversion on a 1985 BMW M635CSi

No CSRs, but how many airborne M1s have you seen?

 

[G-MAN]

The thing that intrigues me about the Cibie CSR lamps is that unlike with H4 lamps, the portion of the lens that generates the right hand flare isn't distinguishable. Here is the 165mm Cibie H4 lamp that I used in my 78 Olds. The fluting on the right side of the lens (looking straight at the lens) that dips down is what causes the right hand flare up (remember the light reflected from the parabolic reflector gets inverted so the "flare" part of the lens is upside down and on the wrong side).

If you look at the fluting in the CSR lens you don't see a similar part that generates the flare, but from the picture of the guy's BMW conversion these lamps have a clearly defined right hand flare just like the H4 lamps. Interesting.

 

[Jonny Z]

Okay. Someone please lobby Congress to change DOT code to ECE

 

[moribundman]

G-MAN, feel free to examine my headlight lens (driver side). Note the lack of the "flare" in the fresnel. The red arrowheads point at the three crosshairs that mark the center points of each lamp. These marks are used in conjunction with the proper optical beam setting device (if available

).

For those who would like to see how an ECE marking on the lens looks:

 

[G-MAN]

Mori, are you getting a sharp cutoff on low beam with a well-defined right hand flare? If so, then I may have to concede that your lights are utilizing hybrid optics similar to the Cibie lights.

 

[moribundman]

G-MAN, I will take a picture of the cutoff for you at the first opportunity. The cutoff is fairly crisp with well defined "ramps" on the right hand side. The left and right headlamps produce 100% identical beam patterns.