Hella 90mm: LED vs Xenon?
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Your info is out of date; you're looking at the old-generation Bi-LED projector. New modules are in this Hella PDF and this one. Also, no, the (older) Bi-LED does not "clearly blow out the foreground", and there's no way from these images to be "sure the reflection off the signs would be blinding". There is not enough info in these pics to make that kind of a judgment. You can't just look at a false-color isoplot and go "Whoah, red, that means there's way too much light"; that's not how this works.
No, I'm aware of the 2nd generation (since 2016) L 5570 bi-LED low-beam and high-beam headlamp. It requires a 120mm wide mount, and thus is incompatible with standard mounting applications.
That wasn't my post; user Mr. Merk replied "Wow, from the images I feel like I would much rather drive with the bixenon. From my uneducated point of view, the LED appears to have a glare spot in the middle, and I'm sure the reflection off the signs would be blinding." It appears you may have accidentally appended it to my post by accident.
However, I would tend to agree with Mr. Merk. Although I would prefer independent third-party testing, this is the best data that I could find, and we can certainly draw valid objective conclusions from it. Admittedly, I used terminology from my photography background, but I stand by my description that the bi-LED appears to produce an over-illuminated patch in the immediate foreground. To use an analogy from photography, "blown out", such that either highlight detail in that area has been lost, or shadow detail elsewhere has been compromised. Further, there is no disagreement that excessive foreground illumination causes a loss in night-adapted vision and thus vision range -- exactly why you helpfully stress the importance of properly-aimed headlights, the harm of blue-tint bulbs, illegal HID bulbs, driving with fog lights on, etc.
Rather than focusing on our errors or reduction to "bi-xenon pwns all", I would be much more helpful to learn your testing and interpretation rationale and collaborating on your data.
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Well, yes, they do have a wider mounting pattern than the other 90mm modules. I suppose this didn't register as a dealbreaker to me because no application was specified and these modules are intended for use wherever you might want to put them (and have the space).
My mistake -- I was probably distracted by irritation at having to clean up after a necro-posting of basically the same question on three old threads.
That's available, and the costs are relatively low for a module like this that mounts to a vertical surface (vs specific-model headlamp assemblies that require complex mounting bucks).
We can compare the various depicted lamps in a relative way -- like this one has longer beam reach, that one has wider foreground, etc. But beyond that, what objective conclusions do you feel can be drawn from these images?
The pictures do not give us enough information to make a valid claim that the foreground is "over-illuminated". That's a judgment call you appear to be making based on...???
OK, so you guess the amount of foreground light produced by the lamp in question would have this effect on a driver's vision. Again, what do you base this guess on?
Also keep in mind that there are UN (ECE) and SAE versions of most of the modules we're talking about here, and their light distributions are going to differ in accordance with the requirements of those two regs...yet there's only one beam (probably the UN beam) depicted for each kind of module.
Yes, and the magnitude of this effect, in practical terms, is pretty complex: how wide and deep is the foreground illumination? What's the ratio of foreground light to distance light? And other factors like that.
When I can share data, I do. Unfortunately, a lot of the data I have access to cannot be published; it's not mine to share. I do my best to strike the appropriate balance of sharing what I can (often by describing what's in front of me) without getting too close to a boundary I cannot cross.
If we can compare beam reach and foreground width, certainly we can compare relative intensity and relative distribution.
Over-illuminated is indeed a comparative judgement call based on the data presented. Note that I'm not claiming they don't meet SAE standards or DOT regulations -- I'm making a narrow judgement that compared to the bi-xenon, the bi-LED has an over-illuminated foreground, and shorter throw and unfavorable beam profile on low.
If you have an alternative judgement, I'd be curious to hear it.
Since you mentioned the 2nd generation bi-LED, I'm you're aware that Hella corrected that excessive foreground illumination. Unfortunately, my application requires the standard mount.
Night vision is hardly complex -- we experience it nightly, and it's covered in any introductory physiology course: intensity and area. We can judge both, as well as foreground to distance ratio, by comparing the data presented.
Rather than arguing over minutiae, I'll ask again for your constructive input.
Over-illuminated is indeed a comparative judgement call based on the data presented. Note that I'm not claiming they don't meet SAE standards or DOT regulations -- I'm making a narrow judgement that compared to the bi-xenon, the bi-LED has an over-illuminated foreground, and shorter throw and unfavorable beam profile on low.
If you have an alternative judgement, I'd be curious to hear it.
Since you mentioned the 2nd generation bi-LED, I'm you're aware that Hella corrected that excessive foreground illumination. Unfortunately, my application requires the standard mount.
Night vision is hardly complex -- we experience it nightly, and it's covered in any introductory physiology course: intensity and area. We can judge both, as well as foreground to distance ratio, by comparing the data presented.
Rather than arguing over minutiae, I'll ask again for your constructive input.
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Yes, we can compare relative intensity at particular locations; we can say lamp A provides more (or less) light than lamp B at location X. We can't say either lamp provides too much light at location X, though. Not without more data that we don't have here.
No, it's not. There is nothing in the images you've posted that can support your guess that the foreground is over-illuminated. You're trying to make sangria with nothing but two grapes and an ice cube -- that's not enough ingredients to wind up with what you want.
Say it five times, say it seventy-five times, say it three hundred and five times...it's still a guess that is not supportable by the images you've posted. It just isn't.
Now this is the kind of thing we can realistically get out of the images you've posted!
What do you see that you consider unfavorable?
The newer headlamp has a different light distribution than the older one, and yes, the newer one gives less foreground light. But "reduced foreground illumination" is not the same as "corrected excessive foreground illumination". The first is an objective statement of fact; the second is an opinion.
Oh, wow...if you think that's right, you are profoundly unequipped to be discussing headlight performance at any scale. Or, alternatively, you know everything there is to know and have nothing to gain by asking questions.
Mesopic vision -- that's the night-driving mode -- is in fact the most complex of the three main visual modes.
Indeed we do. That doesn't make it "not at all complex". You seem to have an affinity for non-sequiturs.
Oh, dear me! OK, this link should be your next stop. And then some better texts on human vision, especially in context of driving -- books like this and this and this. Then, if you want to make a detailed analysis of the various modules you might decide to use, purchase one of each and send them for photometric testing. Then you'll have data usable for reality-based judgments of the lamps' real performance.
Or, alternatively, you could just realize that you're agonizing, probably unnecessarily unless it's the kind of thing that turns you on, over which of the highest-performing 90mm headlamps to buy. If you don't like the light distribution of one versus the other...buy the other, then the problem -- no matter how real or imaginary it might be -- is solved.
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Yes.
And you've apparently already made up your mind and are looking for not guidance but affirmation and argument, so I will leave you to it.
Stay safe out there!
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