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PostPosted: Tue Jun 14, 2016 10:23 am 
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In the BC Interior DOT(CVSE) and RCMpolice are now targetting LED "light bars"

they are permitted only if they are covered. You can get a huge fine for an uncovered "LED light bar"

A recent Facebook post showing a DOT (or as they call thenselves CVSE) vehicle with an uncovered lightbar at a roadcheck caused a $#!+ of extrodinary proportions amongst log truck drivers . Off road truckers use the LED lightbars for low speed off road use.....but are subject to fines when travelling the highway portion of their route, even with the lights off, if they are not covered.

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PostPosted: Tue Jun 14, 2016 10:41 am 
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The "driving light" term is an unfortunate holdover from the early days of night driving, when you almost never met another car on the road. Most night driving was therefore done with the "driving" (high) beam, and only on the rare occasion you met another car did you dip down to the "passing" (low) beam. Now we mostly use low beam because there's constant traffic everywhere, but that "driving light" name makes it sound like "Well, I'm driving, so I'll turn on my driving lights!".

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PostPosted: Tue Jun 14, 2016 2:21 pm 
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SlantSixDan wrote:
jcc wrote:
SlantSixDan wrote:
jcc wrote:
I recently installed in one of my OTR trucks a set of Grote common large reactangle LED units. They are amazing


They are acceptable, but not great. That's a PFR (purchase-for-resale) product Grote brings in from what is diplomatically called "a low-cost country


We must talking about two different items


No, I'm talking about those very same lights you bought. Follow the links I posted for same-size better lights that cost less and are made in America (or don't...your choice!)

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Where they are made is unknown to me.


You want I should repeat myself louder this time, or...? :shrug:

Quote:
The two Summit reviews also say basically the same thing.


What we feel like we're seeing isn't what we're actually seeing. The human visual system is a lousy judge of how well it's doing. "I know what I can see!" seems reasonable, but it doesn't square up with reality because we humans are just not well equipped to accurately evaluate how well or poorly we can see (or how well a headlamp works). Our subjective impressions tend to be very far out of line with objective, real measurements of how well we can (or can't) see. The primary factor that drives subjective ratings of headlamps is foreground light, that is light on the road surface close to the vehicle...which is almost irrelevant; it barely even makes it onto the _bottom_ of the list of factors that determine a headlamp's actual safety performance. A moderate amount of foreground light is necessary so we can use our peripheral vision to keep track of the lane lines and keep our focus up the road where it should be, but too much foreground light works against us: it draws our gaze downward even if we consciously try to keep looking far ahead, and the bright pool of light causes our pupils to constrict, which destroys our distance vision. All of this while creating the feeling that we've got "good" lights. It's not because we're lying to ourselves or fooling ourselves or anything like that, it's because our visual systems just don't work the way it feels like they work.

The upshot of this is that most internet "reviews" of a headlamp are useless at best -- and that would be the case even if we ignore the bogus criteria people often use when "reviewing" headlamps: sharp cutoff on low beam! (also very low on the list of factors that determine a headlamp's actual safety performance, but it looks nifty on the garage wall), "H4" (there are at least as many bad H4 headlamps as good ones), "E-code" (irrelevant; both the US and the UN/"E-code" headlamp standards have lots of room for good and bad headlamps) "High color temperature" (irrelevant at best)...and so on.


Well I guess we are talking about the same fixture, and my professional lighting experience with countless TV shows, concerts, and sporting events must have been just subjective enough to keep me in constant demand for over 4 decades. "Cut off" is extremely important when driving in any inclement weather, fog, or dusty conditions. Color temp is also important ( that doesn't imply higher is always better), stating "reviews are useless" applies only when they cannot be taken with a grain of salt. I mainly drive by what I see, and I see we differ on almost all points.


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PostPosted: Tue Jun 14, 2016 2:56 pm 
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jcc wrote:
"Cut off" is extremely important when driving in any inclement weather, fog, or dusty conditions


No, sir. That's a common misunderstanding. What's important when driving in bad weather is upward stray light. That's light directed between 10° and 60° above horizontal. That's the light that causes backscatter in rain, fog, snow, and dust — whether the headlamp has a sharp cutoff or not. It's two separate issues. There are headlamps with a soft low-beam cutoff that produce little or no upward stray light (and therefore little or no backscatter in bad weather) and there are headlamps with a sharp low-beam cutoff that produce a lot of upward stray light (and are therefore very unpleasant/unsafe to drive with in bad weather because of high levels of backscatter).

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Color temp is also important ( that doesn't imply higher is always better)


Correct -- higher is not necessarily better, and in fact higher CCT (bluer light) has some significant disadvantages in terms of seeing and glare with headlamp light. But marketers love high-CCT headlamps, because it gives them a visual differentiation from "ordinary" headlamps and fuels their babble about how the light is "closer to natural daylight", which it certainly is not -- I'm sure you know as well as I do why everybody talks about CCT but nobody talks about SPD, the spectral power distribution of the light.

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I mainly drive by what I see


No, you don't. None of us does, it just feels like we do. More detailed explanation is in my previous post in this thread.

Quote:
Well I guess we are talking about the same fixture


Yes, we are. Your experience certainly makes you more knowledgeable than those who know nothing about lighting at all, but vehicle lighting is very substantially different than lighting for TV shows, concerts, and sporting events. My professional field is vehicle lighting, and I'm well credentialled and internationally recognised as an expert in it. People pay me consulting fees for the kind of lighting knowledge I dispense here on the forum for free.

You can certainly disagree with me all you like, though.

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Last edited by SlantSixDan on Wed Jun 15, 2016 9:12 am, edited 1 time in total.

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PostPosted: Tue Jun 14, 2016 7:00 pm 
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Careful, folks. Arguing/disagreeing in this manner rarely settles an argument.

Lou

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