burt ragio
10-01-2010, 05:41 AM
Over time we have tried a variety of headlamp bulbs. Searching for a brighter bulb due to poor night vission I found this:
There's only a couple legal variables a conventional 55-watt automotive bulb can use to produce more lumens than another 55-watt bulb
As written, this isn't so. There are automotive headlamp bulbs with nominal 12v 55w ratings that produce 1000 lumens (nominal) at 13.2v —H4 low beam filament, for example — and there are automotive headlamp bulbs with nominal 12v 55w ratings that produce 1800 lumens (nominal) at 13.2v — H2, for example. The design decisions that go into a headlight bulb are many, and they are variable enough to create a very wide range of flux, lifespan, luminance, and other characteristics even if we disregard ancillaries like IR-reflective coatings.
I think you know this, though; I think what you meant is that each type of headlight bulb is regulated with regard to its luminous flux. Quite true. The allowable range is larger than you might suspect; for HB5 (9007) the spec is 1350/1000 lumens (high/low beam) @ 12.8v ±15%. That means the low beam filament can legally emit between 850 and 1150 lumens, a range of thirty percent. That's significantly and substantially greater than the threshold above which flux differences make material differences in seeing performance when driving by headlamp light at night.
The allowable range is different for each bulb type, but it's similarly large. So despite Sylvania's weasel behavior (citing the regulation nominal value for all their different bulb variants...pffft!), there's actually a large difference in flux and lifespan across all the major makers' product lineups for any given bulb type. (I should advise you at this point that some of what I'm posting here has been floating around this board and elsewhere on the internet for quite awhile; I've checked and confirmed enough of the data that I'm comfortable reposting it.)
Here's manufacturer data for output and lifespan at 13.2v for standard-wattage H1 bulbs. The numbers here are a composite of values applicable to the products of the big three makers (Osram-Sylvania, Philips-Narva, Tungsram-GE). Each manufacturer's product in each category is slightly different but not significantly so. I picked H1-type bulbs for this comparison, and while the absolute numbers differ with different bulb types, the relative comparison patterns hold good for whatever filament bulb type we consider (H4, 9006, 9007, whatever). Lifespan is given as Tc.
H1 (plain, standard):
1550 lumens, 650 hours
Long Life:
1460 lumens, 1200 hours
Ultra Long Life (e.g. Osram "Light@Day"):
1430 lumens, 3000 hours
Plus-30 High Efficacy (Osram Super, Sylvania Xtravision, Narva Rangepower+30, Tungsram High Output, Philips Premium or High Visibility):
1700 lumens, 350 hours
Plus-50 Ultra High Efficacy (Philips VisionPlus, Osram Silverstar, Narva Rangepower+50, Tungsram Megalicht, but not Sylvania Silver Star):
1750 lumens, 350 hours
Plus-80/90 Mega High Efficacy (Philips Xtreme Power, Osram Night Breaker):
1780 lumens, 340 hours
Blue coated 'extra white' (Osram CoolBlue, Narva Rangepower Blue, Philips BlueVision or CrystalVision, Tungsram Super Blue or EuroBlue, Sylvania Silver Star or Silver Star Ultra, Wagner TruView, also PIAA, Hoen, Nokya, Polarg, and all the rest of the blue-glass junk):
1380 lumens, 250 hours
So that's the pattern for how lifespan and flux are generally related. BUT, the lumen differences are not the extent of the performance differences. The filament changes required to make a long-life filament (larger mandrel, wider pitch) tend to reduce luminance and beam focus, which shortens seeing distance and makes the light color brownish. But lifespan is lengthened! The opposite filament changes are made to create the "Plus" (+30, +50, +80, +90) or Osram "Hyper" type bulbs: Lifespan is reduced, but the beam focus is better (smaller, tighter-pitch filament) so seeing distance is longer. Luminance is higher, so light color is whiter (literally less brown, not blue-tinted phony-white). These same changes can be rejiggered to hold flux constant with the standard-bulb baseline, but reduce power consumption (Osram and Philips are marketing such bulbs as an eco-friendly option). The takeaway message here is that even if all the filaments put out exactly the same flux, the beam photometry with the long-life bulb would still be inferior compared to the same headlamp equipped with a standard, +30, or +50, or +80/+90 bulb.
There's only a couple legal variables a conventional 55-watt automotive bulb can use to produce more lumens than another 55-watt bulb
As written, this isn't so. There are automotive headlamp bulbs with nominal 12v 55w ratings that produce 1000 lumens (nominal) at 13.2v —H4 low beam filament, for example — and there are automotive headlamp bulbs with nominal 12v 55w ratings that produce 1800 lumens (nominal) at 13.2v — H2, for example. The design decisions that go into a headlight bulb are many, and they are variable enough to create a very wide range of flux, lifespan, luminance, and other characteristics even if we disregard ancillaries like IR-reflective coatings.
I think you know this, though; I think what you meant is that each type of headlight bulb is regulated with regard to its luminous flux. Quite true. The allowable range is larger than you might suspect; for HB5 (9007) the spec is 1350/1000 lumens (high/low beam) @ 12.8v ±15%. That means the low beam filament can legally emit between 850 and 1150 lumens, a range of thirty percent. That's significantly and substantially greater than the threshold above which flux differences make material differences in seeing performance when driving by headlamp light at night.
The allowable range is different for each bulb type, but it's similarly large. So despite Sylvania's weasel behavior (citing the regulation nominal value for all their different bulb variants...pffft!), there's actually a large difference in flux and lifespan across all the major makers' product lineups for any given bulb type. (I should advise you at this point that some of what I'm posting here has been floating around this board and elsewhere on the internet for quite awhile; I've checked and confirmed enough of the data that I'm comfortable reposting it.)
Here's manufacturer data for output and lifespan at 13.2v for standard-wattage H1 bulbs. The numbers here are a composite of values applicable to the products of the big three makers (Osram-Sylvania, Philips-Narva, Tungsram-GE). Each manufacturer's product in each category is slightly different but not significantly so. I picked H1-type bulbs for this comparison, and while the absolute numbers differ with different bulb types, the relative comparison patterns hold good for whatever filament bulb type we consider (H4, 9006, 9007, whatever). Lifespan is given as Tc.
H1 (plain, standard):
1550 lumens, 650 hours
Long Life:
1460 lumens, 1200 hours
Ultra Long Life (e.g. Osram "Light@Day"):
1430 lumens, 3000 hours
Plus-30 High Efficacy (Osram Super, Sylvania Xtravision, Narva Rangepower+30, Tungsram High Output, Philips Premium or High Visibility):
1700 lumens, 350 hours
Plus-50 Ultra High Efficacy (Philips VisionPlus, Osram Silverstar, Narva Rangepower+50, Tungsram Megalicht, but not Sylvania Silver Star):
1750 lumens, 350 hours
Plus-80/90 Mega High Efficacy (Philips Xtreme Power, Osram Night Breaker):
1780 lumens, 340 hours
Blue coated 'extra white' (Osram CoolBlue, Narva Rangepower Blue, Philips BlueVision or CrystalVision, Tungsram Super Blue or EuroBlue, Sylvania Silver Star or Silver Star Ultra, Wagner TruView, also PIAA, Hoen, Nokya, Polarg, and all the rest of the blue-glass junk):
1380 lumens, 250 hours
So that's the pattern for how lifespan and flux are generally related. BUT, the lumen differences are not the extent of the performance differences. The filament changes required to make a long-life filament (larger mandrel, wider pitch) tend to reduce luminance and beam focus, which shortens seeing distance and makes the light color brownish. But lifespan is lengthened! The opposite filament changes are made to create the "Plus" (+30, +50, +80, +90) or Osram "Hyper" type bulbs: Lifespan is reduced, but the beam focus is better (smaller, tighter-pitch filament) so seeing distance is longer. Luminance is higher, so light color is whiter (literally less brown, not blue-tinted phony-white). These same changes can be rejiggered to hold flux constant with the standard-bulb baseline, but reduce power consumption (Osram and Philips are marketing such bulbs as an eco-friendly option). The takeaway message here is that even if all the filaments put out exactly the same flux, the beam photometry with the long-life bulb would still be inferior compared to the same headlamp equipped with a standard, +30, or +50, or +80/+90 bulb.