H4 Ford Fiesta Bulb Change

[harro]

Hi; For anyone that's interested. I've just swapped out the standard 60/55 H4 no-name halogens, in my wife's 2006 Fiesta, for a set of Phillips Extreme vision Plus 100's . The numbers are an average of both sides, engine running and ambient light less than 100 lux. Low ( dipped ) beam only measured at the brightest part of the beam, measured @ 1M. High ( full ) beam not measured. No name 60/55w averaged 12500 lux. Phillips Extreme vision Plus 100's 60/55w averaged 21300 lux. To my naked eye, the difference was hardly noticible, but that's what I measured, and it'll be interesting to see in darkness, the difference. :thumbsup:

 

[Alaric Darconville]

H No name 60/55w averaged 12500 lux. Phillips Extreme vision Plus 100's 60/55w averaged 21300 lux. To my naked eye, the difference was hardly noticible, but that's what I measured, and it'll be interesting to see in darkness, the difference.

I tried finding just how much it takes to make light look twice as bright-- I think it's something like 4x the actual intensity before it looks like twice the light. We also know of the "inverse square law", but it's really that we're only seeing maybe 1/12th, not 1/4, of the light reflected back to us from an object that is twice as far away as another, due to all the atmospheric scattering and such.

Your own window glass, even if clean as can be and absolutely untinted, is blocking some light.

Still, with your lamps aimed properly, you'll be thanking yourself for upgrading the bulbs. The beam focus will be much better with the Philips bulbs, so other drivers may thank you, too.

 

[harro]

After having taken the vehicle for a night drive, the difference is readily apparent. The ' extremity ' of the low beams seem to be better filled out ( for want of a better analogy ). The low cutoff seems to be sharper or more defined. As well as light down the road, low appears to put more light onto the road shoulders. High is just a better light. Easier to see and a bit more distance. Remember this is only a personal perspective and in no way measured. I think the better light is an acceptable trade for a reduced bulb lifespan, although it would be interesting to hear what sort of lifespan other members are getting from their Phillips extreme 100's.

 

[Alaric Darconville]

After having taken the vehicle for a night drive, the difference is readily apparent. The ' extremity ' of the low beams seem to be better filled out ( for want of a better analogy ). The low cutoff seems to be sharper or more defined. As well as light down the road, low appears to put more light onto the road shoulders. High is just a better light. Easier to see and a bit more distance. Remember this is only a personal perspective and in no way measured.

That's what beam focus will do for you.

I think the better light is an acceptable trade for a reduced bulb lifespan, although it would be interesting to hear what sort of lifespan other members are getting from their Phillips extreme 100's.

How old were the old bulbs? They may have outlasted their useful lifespan, still emitting light but having filaments so horribly degraded from dendritic 'growth' (the bits of filament that flew off when burning and then got redeposited in weird places) that beam focus suffered as a result. One thing about the +100 bulbs is they will fail long before their lumen maintenance and focus becomes much of a problem at all. (Keep spares!)

 

[harro]

That's what beam focus will do for you.

How old were the old bulbs? They may have outlasted their useful lifespan, still emitting light but having filaments so horribly degraded from dendritic 'growth' (the bits of filament that flew off when burning and then got redeposited in weird places) that beam focus suffered as a result. One thing about the +100 bulbs is they will fail long before their lumen maintenance and focus becomes much of a problem at all. (Keep spares!)

Quite old. I actually took the time to have a bit of a look at them under a 4x magnifying glass, and as you've stated, they were suffering noticibly from dendritic growth. The low fillaments ( naturally ) were worse than the high ones. Spares on hand is a wise and sagely piece of advise. Cheers... Mike.

 

[-Virgil-]

I tried finding just how much it takes to make light look twice as bright

The answer is hugely variable, because "brightness" is a subjective impression highly dependent on many situational factors.

 

[Alaric Darconville]

The answer is hugely variable, because "brightness" is a subjective impression highly dependent on many situational factors.

Could explain why I couldn't find it! I've heard 4x as a "rule of thumb" but even our thumbs can vary in width :)

It's also probably on some sort of logarithmic function, too. 10 lumens vs 5 lumens may look "twice as bright" in a dark room to some, but it may require 50 lumens to look twice as bright as 10-- but 3600lm vs 1800lm be noticeable but hard to really assess. 128,000lm vs 64,000 may be nearly indistinguishable. It's the whole "absolute threshold" and "sensory threshold" thing. (Seriously, I need to reread some books-- but I guess it's good that I know I need to know instead of not knowing it's a thing to be known.)