Stern is becoming mainstream in his old age. Back in the day, he got kicked off just about every automotive list on the Net for abusing anyone who dared question him on anything. Beyond lighting, he is quite an authority on Iacocca-ero Mopars and vintage Volvos.
If you dare lock horns with him, besides knowing your stuff you had better have a rhino-thick skin and an extensive and highly colorful vocabulary. My instinct is that Stu will duck this one, as he has in the past proven he has neither. Mac on 12/6/06 10:45 PM, [EMAIL PROTECTED] at [EMAIL PROTECTED] wrote: > Here's a post from the Ritter list taking His Eminence to task. Question is, > will it be Ritter or VanCleef that kicks the poster off? > > << > Message: 10 > Date: Wed, 6 Dec 2006 12:29:30 -0600 > From: "Gerry Visel" <[EMAIL PROTECTED]> > Subject: [MB] Automotive Lighting Query > > I received the following from Daniel Stern after asking him about > the recent lighting questions on the list here. For what it's worth, > I'd rather see a few sparks fly here than on the road! > > Gerry > > ---------- Forwarded message ---------- > From: Daniel Stern Lighting <[EMAIL PROTECTED]> > Date: Dec 6, 2006 11:54 AM > Subject: Re: Fwd: [Fwd: Re: Automotive Lighting Query] > To: Gerry Visel <[EMAIL PROTECTED]> > > > Hi, GV. > > Numerous times in the past, Stu has advocated wiring up H4 headlamps such > that the high and low beam filaments can be burned at the same time. See > for example http://www.mbca.org/pages/Star/articles/w124.htm . If I am not > mistaken, this same advice is contained in his W124 "bible", and he > has repeated it widely in various discussion forums. > > It is bad and improper advice for the following reason: > > Two-filament headlight bulbs are pressurized to over 12 atmospheres *when > cold*. Basic laws of chemistry (PV=nRT) tell us that with no escape, the > gas pressure inside the bulb will skyrocket with increasing temperature. > These bulbs are not designed to handle the heat, or the current load on > the common filament support lead, of running both filaments at the same > time for more than very brief periods during beam changeover or headlight > flashing. Doing so carries the very real risk of the bulb grenading inside > the headlamp, destroying the lens and reflector with hot, sharp shrapnel. > Some people who think they're clever wire it up this way anyhow, and the > "Brite Box" people have made a business out of this "clever" (not) > modification. > > Running the lows with the highs can only be done safely if the two > functions are produced by separate single-filament bulbs. Very > occasionally, even a reputable maker will produce a bulb with a defect in > its glass or quartz envelope, and such bulbs can explode at random while > in service. Or, if significant liquid water enters the headlamp (as for > example via a faulty seal or cracked lens), and splashes on the hot bulb, > the bulb glass can and often will shatter. But, wiring up the low + high > filament to run at the same time in a 2-filament bulb of any wattage > rating is begging for bulb explosions. This has been explained to Stu > often; each time he has dismissed the explanation, insisted there's no > problem, and carried on refusing to make the connection between his > improper wiring and his bulb-explosion problem. > > There is another very good reason not to run the lows and/or fogs together > with the highs in an H4 system: It doesn't help you see better. The low > beam and fog beam direct their light primarily downward (fog lamps) or > downward/rightward (low beams in right-traffic countries). High beams > direct their light primarily straight ahead. The brighter the foreground > light, the more the driver's pupils constrict, with a resultant > significant decrease in distance vision. There are headlamp systems > (w/multiple single-function beams, not 2-filament) that *rely* on the low > beam being lit when the high beam is on; in these systems the low beam > provides the width and fill, while the high beam produces the distance > reach. But, there are also headlamp systems in which the high beams are > designed to produce the width, fill, and reach all by themselves, and > increasing foreground illumination by means of the low and/or fog beams > just spoils distance vision as described above and at > http://www.danielsternlighting.com/tech/lights/fog_lamps/fog_lamps.html . > Indiscriminately adding more and more and more light by miswiring the > various forward illumination functions usually does not genuinely improve > the safety performance of the lights or the driver's real ability to see > what he needs to see. > > The same goes for just picking the highest-wattage bulbs available. It's > not necessarily the way to optimize lighting performance. As wattage > increases, the size of the filament necessarily increases, both in length > and in diameter. This has a strongly negative effect on beam focus -- the > more closely the filament approximates a point source of light, the better > the beam focus, and the greater the size of the filament the poorer the > beam focus. Effective seeing distance plummets. At the same time, > foreground light goes to nuclear levels, which does two things at the same > time: > > 1) It fools you into thinking you've got "excellent" lighting. We humans > are very poor subjective judges of our visual performance; it's very easy > to create situations in which we think/feel we can see much better (or > much worse) than we actually can. And the number-one way to cause a > subjective impression of "good" lighting is to increase the foreground > light. Of course, some foreground light is necessary so you can keep the > car in-lane, avoid potholes, and see road contours. But, as far as > obstacle avoidance, what you need is *distance* light. Foreground light > doesn't substitute for distance light, and lighting up what's 50 feet in > front of the car is more or less pointless at road speeds much above 30 > mph; you're going to hit it! > > 2) It absolutely kills your distance vision, see above. The brightly-lit > foreground causes your pupils to constrict, with the result that you can > meaningfully see all the irrelevant stuff going on within 50 feet of the > car, and beyond that, you're effectively blind. > > As far as bulbs dying due to finger-touches, that advice is almost but not > completely obsolete. When bulbs' envelopes (the "glass" part of the > burner) were made out of fused quartz, body oil would cause the quartz to > devitrify when it heated up. The result was an opaque blister on the > quartz, which concentrated heat and caused the envelope to blow up like a > balloon or (more commonly) simply shatter. Nowtimes, the vast majority of > automotive halogen bulbs are made out of hardglass, not fused quartz. > Hardglass is impervious to body oil; it does not devitrify if heated up > after having been exposed thereto. But, it's still a good idea not to > touch the envelope (or to wipe it down with alcohol after doing so), for > when the bulb heats up, the oil will be burnt, and the resultant smoke > will condense on the lens and reflector, fogging them. > > If nothing else, the info in this e-mail should keep the sparks flying on > the forums and mailing lists for awhile. > > DS > _______________________________________ > http://www.okiebenz.com > For new parts see official list sponsor: http://www.buymbparts.com/ > For used parts email [EMAIL PROTECTED] > > To Unsubscribe or change delivery options go to: > http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
