"white" LED's vs. incandescent and halogen lights
me
up the asphalt roads very well. Incandescents, halogens, and sodium
lights do better. There seem to be a lot of oranges and yellows on
the illuminated asphalt surface.
My question is why does it appear this way?
I presume that the yellow-orange-red spectral emissions from the LED's
are weaker than the blues. The blues are voltage induced while the y-
o-r's are secondary from phosphors in the casing. Therefore to help
refine my question,
1. Do the stronger blues in the LED cause the weaker yellow/orange/
reds to be less perceived?
2. Are the yellows and oranges on the asphalt caused by sulfur
compounds or by dust and dirt embedded in the tarry surface?
dlzc
On Dec 4, 3:50 pm, me <dhm_at_best_dot_...@yahoo.com> wrote:
> It's obvious that the mundane "white" LED bicycle
> lights do not light up the asphalt roads very well.
Emitted watts in the fraction or single digit watts.
> Incandescents, halogens, and sodium lights
> do better.
Tens to hundreds of watts.
> There seem to be a lot of oranges and yellows on
> the illuminated asphalt surface.
>
> My question is why does it appear this way?
They are painted that way. People that are not fully color blind can
tell the difference, the paints wear well, and they do not bleach too
fast.
> I presume that the yellow-orange-red spectral
> emissions from the LED's are weaker than the
> blues.
The LEDs probably emit only blue, and have the other colors formed by
scattering. Much like the "white light" from a fluorescent light.
> The blues are voltage induced while the y-
> o-r's are secondary from phosphors in the casing.
> Therefore to help refine my question,
>
> 1. Do the stronger blues in the LED cause the
> weaker yellow/orange/reds to be less perceived?
No, I believe it is a sensitivity in the eye. Blue takes more photons
to fire. Especially for eyes that are triggering mostly rods (black
and white) rather than cones (color).
> 2. Are the yellows and oranges on the asphalt
> caused by sulfur compounds or by dust and dirt
> embedded in the tarry surface?
Probably just scattering losses. Energy is lost, which reduces the
wavelength. And the rod/cone thing.
My two cents.
David A. Smith
Nate Nagel
But if you compare an LED bicycle light to a comparable halogen bicycle
light, you'll prefer the LED. to paraphrase, "there's no substitute for
more power."
nate
(and injection is nice, but I'd rather...)
--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel
Mark Thorson
>
> The LEDs probably emit only blue, and have the other colors formed by
> scattering. Much like the "white light" from a fluorescent light.
Scattering? It's fluorescence. A UV LED excites
a set of phosphors that emit white light. That's
what a white LED is.
alie...@gmail.com
> It's obvious that the mundane "white" LED bicycle lights do not light
> up the asphalt roads very well. Incandescents, halogens, and sodium
> lights do better. There seem to be a lot of oranges and yellows on
> the illuminated asphalt surface.
>
> My question is why does it appear this way?
>
> I presume that the yellow-orange-red spectral emissions from the LED's
> are weaker than the blues. The blues are voltage induced while the y-
> o-r's are secondary from phosphors in the casing. Therefore to help
> refine my question,
>
> 1. Do the stronger blues in the LED cause the weaker yellow/orange/
> reds to be less perceived?
"White" LEDs have a strong peak in the blue and a nearly Gaussian
curve centered in the green, extending from the blue-green to the red.
They're kinda weak in the tails. Do a Google Image search for "white
led spectrum" and see for yourself.
The other lamp types you mention are stronger in the red, which the
eye is more sensitive to, particularly at night.
> 2. Are the yellows and oranges on the asphalt caused by sulfur
> compounds or by dust and dirt embedded in the tarry surface?
Asphalt may look black to the casual glance, but reflectance spectra
tell the tale:
http://www.geog.utah.edu/~chen/
Click on the various locations, check out the various surfaces.
Notice for instance "new paving, dark black asphalt, not mixed with
gravel":
http://www.geog.utah.edu/~chen/aspd2.html
is pretty flat, but "old, dirty asphalt paving":
http://www.geog.utah.edu/~chen/aspa.html
rises from the short wavelength (blue) to the long wavelength (red)
end.
...dirty asphalt just reflects red better.
Mark L. Fergerson
Bill Penrose
> 2. Are the yellows and oranges on the asphalt caused by sulfur
> compounds or by dust and dirt embedded in the tarry surface?
I don't see them. I see shades of blue-gray, which is nearly useless
when walking over dark surfaces. Even moonlight is better than white
LEDs.
DB
pm
> On Dec 4, 2:50 pm, me <dhm_at_best_dot_...@yahoo.com> wrote:
>
> > It's obvious that the mundane "white" LED bicycle lights do not light
> > up the asphalt roads very well. Incandescents, halogens, and sodium
> > lights do better. There seem to be a lot of oranges and yellows on
> > the illuminated asphalt surface.
>
> > My question is why does it appear this way?
>
> > I presume that the yellow-orange-red spectral emissions from the LED's
> > are weaker than the blues. The blues are voltage induced while the y-
> > o-r's are secondary from phosphors in the casing. Therefore to help
> > refine my question,
>
> > 1. Do the stronger blues in the LED cause the weaker yellow/orange/
> > reds to be less perceived?
>
> "White" LEDs have a strong peak in the blue and a nearly Gaussian
> curve centered in the green, extending from the blue-green to the red.
> They're kinda weak in the tails. Do a Google Image search for "white
> led spectrum" and see for yourself.
>
> The other lamp types you mention are stronger in the red, which the
> eye is more sensitive to, particularly at night.
Red map lights are used to preserve dark adaptation because rods _do
not_ respond to them. Rods are most sensitive somewhere in the blue-
green. Do a google image search on "rod sensitivity," etc. Combine
with your previous google image search and you will find that the peak
sensitivity for rods coincides with the "dip" in the typical white LED
spectrum.
-pm
Chalo
>
> It's obvious that the mundane "white" LED bicycle lights do not light
> up the asphalt roads very well. Incandescents, halogens, and sodium
> lights do better.
"Mundane" 5mm white LEDs are very low-powered-- typically .07 watts
each-- with poor color rendition. Often, these are overdriven at
around 0.2W to squeeze a bit more light out of them, but this has the
side effect of pushing their color balance farther into the blue
range.
Quality high-flux LEDs like Luxeon, Cree, or Seoul Semiconductor
emitters of nominally 1W or more are not only very bright, but also
very reasonable in their color balance. DiNotte, Niterider, Light &
Motion, Cygolite, Busch & Mueller, and other reputable manufacturers
use high performance, color graded LEDs in their better lights. The
results are categorically better than incandescents (halogen, krypton,
etc.) of similar power.
Generic 5mm white LEDs cost a few cents each at the wholesale level.
They are excellent in terms of cost-effectiveness and power
efficiency. But if you want to see things rather than just be seen by
other road users, you'll need either lots of them, or else better
quality lighting.
Chalo
alie...@gmail.com
The ~430 nm rod peak (beware line wrap):
is a bit offset from the LED dip at 475 nm.
http://www.mvlc.info/images/photos/led/spectral3.jpg
Also, I should have been clearer; cones are more sensitive to red
than to blue.
IMO though WRT the OP's question the deal-breaker is the greater
reflectivity of asphalt in the red independent of light intensity;
illuminated by incandescent etc. lamps it has red-orangish highlights
as the OP says, but under LED illumination it's just black.
There's also the time factor:
http://www.phys.ufl.edu/~avery/course/3400/vision/dark_adaptation.gif
If one doesn't ride long enough to get dark-adapted, the greater
sensitivity of the rods doesn't come into play.
Anyway, isn't the point of a headlight partly to get the rider's
vision out of the scotopic and at least into the mesopic regime?
Personally I have no problem with bluish LEDs while night biking. To
me it doesn't look "wrong", just different.
Mark L. Fergerson
Brendan Gillatt
Hash: SHA1
dlzc wrote:
> Dear me:
>
> On Dec 4, 3:50 pm, me <dhm_at_best_dot_...@yahoo.com> wrote:
>> It's obvious that the mundane "white" LED bicycle
>> lights do not light up the asphalt roads very well.
>
> Emitted watts in the fraction or single digit watts.
>
>> Incandescents, halogens, and sodium lights
>> do better.
>
> Tens to hundreds of watts.
That is an unfair comparison--the _light_ power output of a halogen bulb
is much less than a modern LED for the same electrical power input.
- --
Brendan Gillatt | GPG Key: 0xBF6A0D94
brendan {a} brendangillatt (dot) co (dot) uk
http://www.brendangillatt.co.uk
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Mr. Benn
news:7dqdnRJKOqR5_ofW...@pipex.net:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> dlzc wrote:
>> Dear me:
>>
>> On Dec 4, 3:50 pm, me <dhm_at_best_dot_...@yahoo.com> wrote:
>>> It's obvious that the mundane "white" LED bicycle
>>> lights do not light up the asphalt roads very well.
>>
>> Emitted watts in the fraction or single digit watts.
>>
>>> Incandescents, halogens, and sodium lights
>>> do better.
>>
>> Tens to hundreds of watts.
>
> That is an unfair comparison--the _light_ power output of a halogen bulb
> is much less than a modern LED for the same electrical power input.
>
The latest LEDs from Cree now produce more than twice the amount of light
that a compact fluorescent tube (CFT - otherwise know as an energy-saving
lamp) produces for the same amount of electrical power. CFTs produce
around 3-4 times the light of a halogen lamp.
Androcles
"Mr. Benn" <%%@invalid.invalid> wrote in message
news:hfdslf$ghr$1...@news.eternal-september.org...
The latest fireflies from Nature now produce more than a million times the
amount
of light that a compact LED produces for even less electrical power.
dlzc
On Dec 5, 6:45 am, Brendan Gillatt
<brendanREMOVET...@brendanREMOVETHISgillatt.co.uk> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> dlzc wrote:
> > Dear me:
>
> > On Dec 4, 3:50 pm, me <dhm_at_best_dot_...@yahoo.com> wrote:
> >> It's obvious that the mundane "white" LED bicycle
> >> lights do not light up the asphalt roads very well.
>
> > Emitted watts in the fraction or single digit watts.
>
> >> Incandescents, halogens, and sodium lights
> >> do better.
>
> > Tens to hundreds of watts.
>
> That is an unfair comparison--the _light_ power
> output of a halogen bulb is much less than a modern
> LED for the same electrical power input.
How is that an *unfair* comparison? The LED energy goes nearly
straight to making light, so you can get light from smaller
batteries. The other technologies get a subset of mass to a "natural"
emission temperature, so there is significant heat storage (lost at
end-of-cycle), and heat losses while operating.
You can get more light from a halogen (etc) source, because you don't
have to construct it out of unitary cells of "fixed" output. You just
need a bigger battery...
Not unfair, just physics.
David A. Smith
Brendan Gillatt
Hash: SHA1
dlzc wrote:
> How is that an *unfair* comparison? The LED energy goes nearly
> straight to making light, so you can get light from smaller
> batteries. The other technologies get a subset of mass to a "natural"
> emission temperature, so there is significant heat storage (lost at
> end-of-cycle), and heat losses while operating.
Because you are saying that LED lights emit power in the "fraction or
single digit watts" and that "Incandescents, halogens, and sodium lights"
emit with "Tens to hundreds of watts". This is only true if you supply
the former with a smaller amount of electrical energy than the later.
Hence it is an unfair comparison.
> You can get more light from a halogen (etc) source, because you don't
> have to construct it out of unitary cells of "fixed" output. You just
> need a bigger battery...
>
Huh?
You can make an LED driver of close to 90% efficiency with inputs above
and/or below the battery voltage. There is no need for unitary cells of
fixed output.
- --
Brendan Gillatt | GPG Key: 0xBF6A0D94
brendan {a} brendangillatt (dot) co (dot) uk
http://www.brendangillatt.co.uk
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Nate Nagel
Do they come in a dynohub model? :/
nate
pm
>
> is a bit offset from the LED dip at 475 nm.
>
> http://www.mvlc.info/images/photos/led/spectral3.jpg
>
> Also, I should have been clearer; cones are more sensitive to red
> than to blue.
Maybe you were thinking cones, but still I don't buy it as an
explanation for perceived LED problems. The yellow phosphor is almost
exactly (and not by accident) where you'd want it to be to maximize
luminous efficiency (the CIE y-bar color matching function and the
yellow phosphor both peaking at about 550 nm)
>
> IMO though WRT the OP's question the deal-breaker is the greater
> reflectivity of asphalt in the red independent of light intensity;
> illuminated by incandescent etc. lamps it has red-orangish highlights
> as the OP says, but under LED illumination it's just black.
I think this is part of the problem for sure.
dlzc
On Dec 5, 10:04 am, Brendan Gillatt
<brendanREMOVET...@brendanREMOVETHISgillatt.co.uk> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> dlzcwrote:
> > How is that an *unfair* comparison? The
> > LED energy goes nearly straight to making
> > light, so you can get light from smaller
> > batteries. The other technologies get a
> > subset of mass to a "natural" emission
> > temperature, so there is significant heat
> > storage (lost at end-of-cycle), and heat
> > losses while operating.
>
> Because you are saying that LED lights emit
> power in the "fraction or single digit watts"
> and that "Incandescents, halogens, and
> sodium lights" emit with "Tens to hundreds
> of watts".
I'm talking about power *draw*.
> This is only true if you supply the former with
> a smaller amount of electrical energy than the
> later.
Which is what I was talking about, even though that was absolutely not
clear.
> Hence it is an unfair comparison.
As I wrote it, you are correct.
> > You can get more light from a halogen (etc)
> > source, because you don't have to construct
> > it out of unitary cells of "fixed" output. You just
> > need a bigger battery...
>
> Huh?
LEDs are, in the cheap ones I have seen, makes of small individual
units. Maybe they don't have to be, but they have been so far.
> You can make an LED driver of close to 90%
> efficiency with inputs above and/or below the
> battery voltage. There is no need for unitary
> cells of fixed output.
Yes, thank you. I like LEDs too, in case that was not clear.
David A. Smith
Michael Press
<997b3349-b0fc-4c6f...@g4g2000pri.googlegroups.com>,
"nu...@bid.nes" <alie...@gmail.com> wrote:
> On Dec 4, 2:50 pm, me <dhm_at_best_dot_...@yahoo.com> wrote:
> > It's obvious that the mundane "white" LED bicycle lights do not light
> > up the asphalt roads very well. Incandescents, halogens, and sodium
> > lights do better. There seem to be a lot of oranges and yellows on
> > the illuminated asphalt surface.
> >
> > My question is why does it appear this way?
> >
> > I presume that the yellow-orange-red spectral emissions from the LED's
> > are weaker than the blues. The blues are voltage induced while the y-
> > o-r's are secondary from phosphors in the casing. Therefore to help
> > refine my question,
> >
> > 1. Do the stronger blues in the LED cause the weaker yellow/orange/
> > reds to be less perceived?
>
> "White" LEDs have a strong peak in the blue and a nearly Gaussian
> curve centered in the green, extending from the blue-green to the red.
> They're kinda weak in the tails. Do a Google Image search for "white
> led spectrum" and see for yourself.
>
> The other lamp types you mention are stronger in the red, which the
> eye is more sensitive to, particularly at night.
The human eye is not more sensitive to red.
It's peak sensitivity is ~560 nm---between yellow and green.
--
Michael Press
alie...@gmail.com
> In article
> <997b3349-b0fc-4c6f-bbae-d98a3dcf7...@g4g2000pri.googlegroups.com>,
(sigh)
Read the whole thread.
Mark L. Fergerson
Peter Cole
> It's obvious that the mundane "white" LED bicycle lights do not light
> up the asphalt roads very well. Incandescents, halogens, and sodium
> lights do better.
That's not at all obvious to me.
_
> In article
> <997b3349-b0fc-4c6f...@g4g2000pri.googlegroups.com>,
> "nu...@bid.nes" <alie...@gmail.com> wrote:
>
>> On Dec 4, 2:50锟絧m, me <dhm_at_best_dot_...@yahoo.com> wrote:
>>> It's obvious that the mundane "white" LED bicycle lights do not light
>>> up the asphalt roads very well. 锟絀ncandescents, halogens, and sodium
>>> lights do better. 锟絋here seem to be a lot of oranges and yellows on
>>> the illuminated asphalt surface.
>>>
>>> My question is why does it appear this way?
>>>
>>> I presume that the yellow-orange-red spectral emissions from the LED's
>>> are weaker than the blues. 锟絋he blues are voltage induced while the y-
>>> o-r's are secondary from phosphors in the casing. 锟絋herefore to help
>>> refine my question,
>>>
>>> 1. 锟紻o the stronger blues in the LED cause the weaker yellow/orange/
>>> reds to be less perceived?
>>
>> "White" LEDs have a strong peak in the blue and a nearly Gaussian
>> curve centered in the green, extending from the blue-green to the red.
>> They're kinda weak in the tails. Do a Google Image search for "white
>> led spectrum" and see for yourself.
>>
>> The other lamp types you mention are stronger in the red, which the
>> eye is more sensitive to, particularly at night.
>
> The human eye is not more sensitive to red.
> It's peak sensitivity is ~560 nm---between yellow and green.
At low levels yes; at higher levels the blue response is a bit higher (it's
possible that anomalous trichromats have different sensitivities as well as
different peaks, but a) they are rare, and b) I doubt the differences are
great).
True night vision is colourless - matching the emitted colour to the most
sensitive portion of the eye can be a factor in that case - but of course
it is a multi-variate problem with competing factors such as luminous
efficiency, battery weight, cost, percentage of
dim-but-not-true-night-vision cycling, see versus be seen, general
construction and reliability, etctera.
Androcles
"Peter Cole" <peter...@verizon.net> wrote in message
news:hfgfrt$9f6$1...@news.eternal-september.org...
Then try it and it will be (unless you happen to be blind).
Not that LED bicycle lights were ever intended to illuminate asphalt,
they merely provide a legally required source of light for oncoming
vehicle drivers to observe. If you want to illuminate asphalt, use more
candlepower.
It's obvious (to anyone with eyes and half a brain) that the "white" LED
bicycle lights do not illuminate asphalt roads very well. Incandescents,
thirty-six
> "Peter Cole" <peter_c...@verizon.net> wrote in message
Are "white" LEDs legally white. As in, a white lamp must be fitted to
the front of the vehicle and a red lamp must (usually) be fitted to
the rear and operational during times of darkness.
Frank Krygowski
> "Peter Cole" <peter_c...@verizon.net> wrote in message
>
> news:hfgfrt$9f6$1...@news.eternal-september.org...
>
> > me wrote:
> >> It's obvious that the mundane "white" LED bicycle lights do not light
> >> up the asphalt roads very well. Incandescents, halogens, and sodium
> >> lights do better.
>
> > That's not at all obvious to me.
>
> Then try it and it will be (unless you happen to be blind).
> they merely provide a legally required source of light for oncoming
> vehicle drivers to observe. If you want to illuminate asphalt, use more
> candlepower.
"Not that LED bicycle lights were ever intended to illuminate
asphalt"? That's thoroughly wrong. For just one example, the LED
headlight at http://www.nabendynamo.de/english/index.html is used by
people riding in all-night competitions on the road.
Read some discussion on LED headlights at http://www.peterwhitecycles.com/schmidt-headlights.asp
or at http://www.blayleys.com/articles/lights/page3.htm
It seems you're about a decade behind times ...
>
> It's obvious (to anyone with eyes and half a brain) that the "white" LED
> bicycle lights do not illuminate asphalt roads very well.
... and more than a little rude, as well.
- Frank Krygowski
Androcles
"thirty-six" <thirt...@live.co.uk> wrote in message
news:8d8e6e8b-0984-4fb8...@p30g2000vbt.googlegroups.com...
==========================================
Yes, they are. If you compare older incandescent car headlights
with later halogen lights one will appear to have a yellow tinge
whilst the other appears bluish. Both are legally white.
http://www.catdiaries.co.uk/images/photography_personal/img_1.jpg
From a legal standpoint you can use a hurricane lamp if you wish,
or even a candle with a glass wind shield. There is no legal requirement
to use an electric light, the law was made before electric lighting
became commonly available.
http://img1.photographersdirect.com/img/15262/wm/pd1068794.jpg
Legally the lights are required so that you can be seen, not for you to
see by; in Britain a high brightness red rear fog lamp is now a legal
requirement.
Androcles
"Frank Krygowski" <frkr...@gmail.com> wrote in message
news:38886938-5bb5-4147...@g1g2000vbr.googlegroups.com...
On Dec 6, 10:38 am, "Androcles" <Headmas...@Hogwarts.physics_q> wrote:
> "Peter Cole" <peter_c...@verizon.net> wrote in message
>
> news:hfgfrt$9f6$1...@news.eternal-september.org...
>
> > me wrote:
> >> It's obvious that the mundane "white" LED bicycle lights do not light
> >> up the asphalt roads very well. Incandescents, halogens, and sodium
> >> lights do better.
>
> > That's not at all obvious to me.
>
> Then try it and it will be (unless you happen to be blind).
> LED bicycle lights were ever intended to illuminate asphalt,
> they merely provide a legally required source of light for oncoming
> vehicle drivers to observe. If you want to illuminate asphalt, use more
> candlepower.
"Not that LED bicycle lights were ever intended to illuminate
asphalt"? That's thoroughly wrong. For just one example, the LED
headlight at http://www.nabendynamo.de/english/index.html is used by
people riding in all-night competitions on the road.
================================================
Listen up, dim bulb, if you want to illuminate asphalt then use more
candlepower, it's that fuckin' simple.
Read some discussion on LED headlights at
http://www.peterwhitecycles.com/schmidt-headlights.asp
or at http://www.blayleys.com/articles/lights/page3.htm
It seems you're about a decade behind times ...
>
> It's obvious (to anyone with eyes and half a brain) that the "white" LED
> bicycle lights do not illuminate asphalt roads very well.
... and more than a little rude, as well.
=============================================
As are you.
*plonk*
Do not reply to this generic message, it was automatically generated;
you have been kill-filed, either for being boringly stupid, repetitive,
unfunny, ineducable, repeatedly posting politics, religion or off-topic
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or permutation of the aforementioned reasons; any reply will go unread.
Boringly stupid is the most common cause of kill-filing, but because
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I'm fully aware that you may be so stupid as to reply, but the purpose
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I hope you find this explanation is satisfactory but even if you don't,
damnly my frank, I don't give a dear. Have a nice day and fuck off.
Just zis Guy, you know?
<Headm...@Hogwarts.physics_q> wrote:
>It's obvious (to anyone with eyes and half a brain) that the "white" LED
>bicycle lights do not illuminate asphalt roads very well. Incandescents,
>halogens, and sodium lights do better.
Ah, a citation to the International Journal of Because I Said So.
Always the most compelling of arguments, so much better than Andreas
Oehler's much more time-consuming approach of actually testing them
and posting the results.
Guy
--
http://www.chapmancentral.co.uk/urc
GPG public key at http://www.chapmancentral.co.uk/pgp-public-key.txt
Androcles
"Just zis Guy, you know?" <guy.c...@spamcop.net> wrote in message
news:s4pnh5t3nag8pfo74...@4ax.com...
> On Sun, 6 Dec 2009 15:38:24 -0000, "Androcles"
> <Headm...@Hogwarts.physics_q> wrote:
>
>>It's obvious (to anyone with eyes and half a brain) that the "white" LED
>>bicycle lights do not illuminate asphalt roads very well. Incandescents,
>>halogens, and sodium lights do better.
>
Chapman says so.
You were careful to snip
"Then try it and it will be [obvious] (unless you happen to be blind)" to
show
your bias and prejudice, weren't you, fuckhead?
Just zis Guy, you know?
<Headm...@Hogwarts.physics_q> wrote:
>You were careful to snip
>"Then try it and it will be [obvious] (unless you happen to be blind)" to
>show
>your bias and prejudice, weren't you, fuckhead?
You set followups to your home group, alt.morons. I guess that your
fellow morons must find this intrusive so I set the groups back to the
right place. No, I didn't snip anything meaningful, the appeal to
what is "obvious" seems to me to be highly questionable with the
current generation of LED headlights, which produce a bright
blue-white light which seems to light up blacktop just fine. The
yellow of sodium vapour lamps is, I believe, more about cutting
through fog and mist than about illuminating blacktop.
Tom Keats
Anything that lights-up the road surface enough to cast
shadows to create a 3-D effect so one can see well enough
to ride by is good.
Anything that casts enough of a spot on the street ahead
while announcing one's arrival into an intersection is
also good.
So many riders want to totally dump the onus of care on
drivers, rather than assume responsibility for their own
conduct.
There's a big difference between /having/ some sort of
bike light, and actually /using/ it beyond just switching
it on.
Riding in the darkness of night is not an endeavour to
be undertaken by the stupid.
Or. it is, but not for long.
--
Nothing is safe from me.
I'm really at:
tkeats curlicue vcn dot bc dot ca
Michael Press
<262ae817-5c88-489b...@x5g2000prf.googlegroups.com>,
"nu...@bid.nes" <alie...@gmail.com> wrote:
I read it. The human eye is not more sensitive to red.
--
Michael Press
Peter Cole
> It's obvious (to anyone with eyes and half a brain) that the "white" LED
> bicycle lights do not illuminate asphalt roads very well. Incandescents,
> halogens, and sodium lights do better.
A whole brain gives a different impression.
Androcles
Ok, so you hallucinate that a pissy little Xmas tree light
is brighter than a sodium or mercury vapour street light.
Get your local authority to install them on lamp posts.
Just zis Guy, you know?
<Headm...@Hogwarts.physics_q> wrote:
>*plonk*
Seems that "Androcles" is a total plonker. Who'd have thought it.
Chalo
Same here. Watt for watt, there is no comparison. LEDs, even cheap
'n crappy 5mm LEDs that are overdriven and color-distorted, put out so
much more light for a given amount of juice compared to incandescents
that you might as well compare them to cigarette lighters or
glowsticks.
Chalo
Frank Krygowski
Careful, Chalo! "Androcles" may plonk you. And I'm sure that will
bother you just as much as it bothered me! ;-)
- Frank Krygowski
Keitht
filters in - red and green - to pick out some of the lumpy bits?
--
Its never too late to reinvent the bicycle
Keitht
> "thirty-six" <thirt...@live.co.uk> wrote in message
> Are "white" LEDs legally white. As in, a white lamp must be fitted to
> the front of the vehicle and a red lamp must (usually) be fitted to
> the rear and operational during times of darkness.
> ==========================================
> Yes, they are. If you compare older incandescent car headlights
> with later halogen lights one will appear to have a yellow tinge
> whilst the other appears bluish. Both are legally white.
> http://www.catdiaries.co.uk/images/photography_personal/img_1.jpg
> From a legal standpoint you can use a hurricane lamp if you wish,
> or even a candle with a glass wind shield. There is no legal requirement
> to use an electric light, the law was made before electric lighting
> became commonly available.
> http://img1.photographersdirect.com/img/15262/wm/pd1068794.jpg
> Legally the lights are required so that you can be seen, not for you to
> see by; in Britain a high brightness red rear fog lamp is now a legal
> requirement.
>
>
>
>
That was the issue all along - that it's based on power not brightness.
It's how you can have incredibly bright car headlights based on halogen
and other metals and really shite yellowish bulbs that are still bits of
coiled wire - both are perfectly legal as the power consumption is the
same.
LED's gave us the chance to 'shine', the battery life is a bonus.
Peter Clinch
> It's obvious that the mundane "white" LED bicycle lights do not light
> up the asphalt roads very well. Incandescents, halogens, and sodium
> lights do better.
Oh. Last week I had the chance to compare a well respected halogen lamp
(BuM Lumotec Oval) to a well respected LED lamp (BuM IQ Fly) on the same
(unlit, asphalt) road at the same time, both running from dynoubs on
side by side bikes, and the IQ Fly did a damn site better job of
lighting it up.
So obvious to some, perhaps, but not me.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.c...@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
Androcles
"Keitht" <KeithT> wrote in message
news:yLidnVlXK8Y6JIHW...@bt.com...
What you need is a white one on a bicycle to meet legal requirements,
and a cluster of 1 red, 1 green and one blue LED would meet that
requirement. Put one of these on your handlebars and entertain
the oncoming drivers.
http://gadgetwise.blogs.nytimes.com/2009/06/11/whats-an-led-tv/
nailer
Androcles
"Keitht" <KeithT> wrote in message
a legal definition then it should be in lumens, not watts, and wavelength,
not colour. But then, it probably is defined that way. I'm not that much
of a legal eagle to want to find out.
http://en.wikipedia.org/wiki/Luminous_efficacy
thirty-six
> Androcles wrote:
> > "thirty-six" <thirty-...@live.co.uk> wrote in message
I don't think there is any point in attempting to compete with car
headlights. If we can obtain similar brightness and size to a 24W
incandescent (not legal) reversing lamp then we have all the
visibility requirements we need. Experience shows this is way in
excess of what we need to illuminate the road effevtively. I have a
flood type car headlamp reflector of around 3" and would like to see
this with an LED driver fitted if possible.
Martin Brown
> me wrote:
>> It's obvious that the mundane "white" LED bicycle lights do not light
>> up the asphalt roads very well. Incandescents, halogens, and sodium
>> lights do better.
>
> Oh. Last week I had the chance to compare a well respected halogen lamp
> (BuM Lumotec Oval) to a well respected LED lamp (BuM IQ Fly) on the same
> (unlit, asphalt) road at the same time, both running from dynoubs on
> side by side bikes, and the IQ Fly did a damn site better job of
> lighting it up.
>
> So obvious to some, perhaps, but not me.
For the same power consumption an LED based unit should be way brighter
than an ordinary incandescent bulb and a fair bit brighter than a
halogen. Lumens per watt pretty much clinches it. The trade is that you
get better battery life and the same amount of light with the LED device
- at least if the designer knows what he is doing. It is an even better
win for the red tail light since red LEDs are pure red emitters with no
need to filter them and the package is self collimated by design.
The problem is that you don't often get single white LEDs at much beyond
1W total power dissipation so some devices are based on specsmanship.
BTW I have never seen sodium lights fitted to bicycles - do they really
do that in the USA?
Regards,
Martin Brown
Frank Krygowski
wrote:
>
>
> BTW I have never seen sodium lights fitted to bicycles - do they really
> do that in the USA?
They do that only in Androcles' mind. Or more accurately, only in his
deviant arguments. Even he doesn't really believe that.
- Frank Krygowski
Clive George
news:IauTm.3191$ha3....@newsfe19.iad...
> The problem is that you don't often get single white LEDs at much beyond
> 1W total power dissipation so some devices are based on specsmanship.
LEDs bigger than that are well into the mainstream now. B+M's LEDs are 3-4W
single white, and the MTB lights will be bigger than that - some use
multiple LEDs, but they're still quite powerful. ISTR 3W luxeons coming
along several years ago, and the industry has been moving very quickly since
then.
The streetlights mentioned in that test are 167W units with 60 LEDs in
each - and I'd expect them to be quite conservative about lifetime in that
application (they're aiming for 50,000 hours plus at a guess).
Just zis Guy, you know?
<frkr...@gmail.com> wrote:
>> BTW I have never seen sodium lights fitted to bicycles - do they really
>> do that in the USA?
>They do that only in Androcles' mind. Or more accurately, only in his
>deviant arguments. Even he doesn't really believe that.
I wonder if he's channeling Steven Scharf?
Ron Peterson
> The latest fireflies from Nature now produce more than a million times the
> amount
> of light that a compact LED produces for even less electrical power.
White LEDs can have an efficiency of 22% currently compared to a
maximum possible efficiency for white light of 37%, fireflies are only
96% efficient.
--
Ron
Androcles
"Ron Peterson" <r...@shell.core.com> wrote in message
news:f7a06a7e-b97c-47bd...@m16g2000yqc.googlegroups.com...
They'd better change their Duracells over to Energizer Bunny cells, then.
Dirk Bruere at NeoPax
Latest record is around 190 lm/W
http://en.wikipedia.org/wiki/Luminous_efficacy
--
Dirk
http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.blogtalkradio.com/onetribe - Occult Talk Show
Androcles
"Dirk Bruere at NeoPax" <dirk....@gmail.com> wrote in message
news:7obgcuF...@mid.individual.net...
> Ron Peterson wrote:
>> On Dec 5, 9:19 am, "Androcles" <Headmas...@Hogwarts.physics_q> wrote:
>>
>>> The latest fireflies from Nature now produce more than a million times
>>> the
>>> amount
>>> of light that a compact LED produces for even less electrical power.
>>
>> White LEDs can have an efficiency of 22% currently compared to a
>> maximum possible efficiency for white light of 37%, fireflies are only
>> 96% efficient.
>
> Latest record is around 190 lm/W
> http://en.wikipedia.org/wiki/Luminous_efficacy
>
> --
> Dirk
How many watts does a firefly use, then?
Dirk Bruere at NeoPax
No idea, but it is far higher efficiency than any current LED
Androcles
> Androcles wrote:
>> "Dirk Bruere at NeoPax" <dirk....@gmail.com> wrote in message
>> news:7obgcuF...@mid.individual.net...
>>> Ron Peterson wrote:
>>>> On Dec 5, 9:19 am, "Androcles" <Headmas...@Hogwarts.physics_q> wrote:
>>>>
>>>>> The latest fireflies from Nature now produce more than a million times
>>>>> the
>>>>> amount
>>>>> of light that a compact LED produces for even less electrical power.
>>>> White LEDs can have an efficiency of 22% currently compared to a
>>>> maximum possible efficiency for white light of 37%, fireflies are only
>>>> 96% efficient.
>>> Latest record is around 190 lm/W
>>> http://en.wikipedia.org/wiki/Luminous_efficacy
>>>
>>> --
>>> Dirk
>>
>> How many watts does a firefly use, then?
>
> No idea, but it is far higher efficiency than any current LED
>
idea what "none" is.
Peter Cole
According to this:
http://www.nature.com/nphoton/journal/v2/n1/full/nphoton.2007.251.html
and this:
http://www.bioluminescentbeetles.com/introduction.html
New measurements put quantum efficiency of firefly bioluminescence at 41
+/- 7.4%.
"Initially predicted to be around 88% efficient the firefly
bioluminescent quantum yield has recently been accurately identified to
be 41.0 � 7.4% which is still higher than those found in other forms of
bioluminescence, i.e. aequorin (17%), cypridina (28%) and bacteria (30%)
[4]."
me
> me wrote:
> > It's obvious that the mundane "white" LED bicycle lights do not light
> > up the asphalt roads very well. Incandescents, halogens, and sodium
> > lights do better.
>
> Oh. Last week I had the chance to compare a well respected halogen lamp
> (BuM Lumotec Oval) to a well respected LED lamp (BuM IQ Fly) on the same
> (unlit, asphalt) road at the same time, both running from dynoubs on
> side by side bikes, and the IQ Fly did a damn site better job of
> lighting it up.
>
> So obvious to some, perhaps, but not me.
>
> Pete.
> --
ok,
So it looks like I'll have to to some unbiased testing. It will take
a while. Lifestyle hardships get in the way. Just a homeless bum,
you know.
There are issues involving
1. Spectral distribution from the emitting sources of light
2. Spectral reflectance from whatever the light hits
3. Reflective intensity of the individual colors
4. Spectral perception of the individual
5. Calibration of the reflected colors from a camera device and the
display device
6. Mathematical dealings with superposition issues
I have the 'digital color utility' on my aging mac and an older
digital camcorder that I use for stills. I don't have a high quality
LED lamp which costs too much for me to buy so maybe I'll be able to
borrow one to test. I have an ancient 35mm camera with a light meter
that I will have to calibrate and buy a battery for. I'll have to buy
a few LED's and potentiometers from a parts store. I'll try to mount
them on a dissected cateye opticube. I'll use my cheap digital
voltmeter to get the relation between power and illumination. I have
a diffraction grating that might reveal something. I'll mount it on a
toilet paper roll with a slit on the other end, and attach it to the
camera. I'll use my set of oil crayons for color reference that I
previously used to make a panhandling sign.
I figure I'll eventually shoot around 50 still pix. I might add a set
of fluorescent light pix. I suppose I'll web it up eventually.
errata -
1. many asphalt streets I've seen have varying amounts of small
exposed stones (limestone?) embedded on the surface that will reflect
yellows better than blues. Trees and foliage have a lot of yellow
reflectance.
2. Older people may experience yellowing of the lens in their eyes,
causing less sensitivity to blues. Recently I recommended a 2 front-
light setup for a 60-something biker - one small blue-light flasher,
and a larger halogen with adjustable focus mounted on a flashlight
holder. If you use the halogen only occasionally, the batteries
should last a long time :)
thirty-six
You'll also want a reference grey card (shirt card) and a tape
measure..
Frank Krygowski
Alternately, you could ride your bike and look. That's worked for
many of us.
It's a simple plan, but we like it.
- Frank Krygowski
N8N
> me wrote:
> > It's obvious that the mundane "white" LED bicycle lights do not light
> > up the asphalt roads very well. Incandescents, halogens, and sodium
> > lights do better.
>
> Oh. Last week I had the chance to compare a well respected halogen lamp
> (BuM Lumotec Oval) to a well respected LED lamp (BuM IQ Fly) on the same
> (unlit, asphalt) road at the same time, both running from dynoubs on
> side by side bikes, and the IQ Fly did a damn site better job of
> lighting it up.
>
> So obvious to some, perhaps, but not me.
Odd, I recently replaced a standard Lumotec with an IQ Cyo and the
difference to me was astonishing - in favor of the IQ Cyo.
nate
Chalo
>
> Buy a light. If it's not bright enough for you, buy something else.
> With the time you save from NOT doing the tests you outlined, study
> investments. You'll make much more money than you'll ever spend on
> lights.
Oy! If only it were so!
thirty-six
I've already sorted that. In conditions were road lighting could be
better and I need projection on the road, by current blue tint LED
mixes well with the available yellow sodium. Under better road
lighting then the blueness is more noticeable to other road users.
With no road lighting, the level of illumination is relatively poor
and is best supplemented with an incandescent of normal 2-3W levels.
it would be nice to see specifically what defects are and are not
shown up by the LED without risking riding unlit roads.at speed.
Ron Peterson
> I've already sorted that. In conditions were road lighting could be
> better and I need projection on the road, by current blue tint LED
> mixes well with the available yellow sodium. Under better road
> lighting then the blueness is more noticeable to other road users.
> With no road lighting, the level of illumination is relatively poor
> and is best supplemented with an incandescent of normal 2-3W levels.
> it would be nice to see specifically what defects are and are not
> shown up by the LED without risking riding unlit roads.at speed.
The rods of the eye are most sensitive to blue light.
--
Ron
Tom Keats
There seems to be a mindset that that is indeed what
bike riders need to do, either in terms of o/p wattage
or brightness. In city traffic, blinking lights + speed
difference + positioning on the street does the trick
nicely -- as long as the batteries don't fade.
On lightly-driven country highways at night, just about
any kind of light sticks out like a sore thumb.
> If we can obtain similar brightness and size to a 24W
> incandescent (not legal) reversing lamp then we have all the
> visibility requirements we need. Experience shows this is way in
> excess of what we need to illuminate the road effevtively. I have a
> flood type car headlamp reflector of around 3" and would like to see
> this with an LED driver fitted if possible.
It's very nice to be able to cast a luminous spot on the
city streets at night when approaching intersections in order
to announce one's approach to any possible cross traffic;
epecially at blind intersections, which should be dealt
with gingerly anyways. 'Cuz chances are, any cross-traffic
drivers there won't be alert to the approach of car
headlights, let alone bike lights. So we have to be
alert for them.
I guess just having lights on is no excuse for having
one's guard down.
cheers,
Tom
--
Nothing is safe from me.
I'm really at:
tkeats curlicue vcn dot bc dot ca
Just zis Guy, you know?
And the people who actually know about lighting are audax riders, who
ride in all kinds of lighting conditions right down to pitch black and
in all kinds of weathers.
I'd also suggest that anyone who judges LED lights without having
tried the most recent offerings from B&M and others, is probably not
going to be in possession of all the facts. They have improved
dramatically in recent times. A D-Lumotec might justly be
characterised as thirty-six described, but the IQ Cyo definitely
can't.
LEDs have definitely moved from the being-seen into the seeing-by
category.
Androcles
"Tom Keats" <tkeat...@hotmail.com> wrote in message
news:jpevfh...@news.eternal-september.org...
The weight won't affect your speed, just your acceleration,
and when you get tired pedalling you can run a motor from
it. Electrically propelled bicycles have been around for a while
now.
Anyway, bikes are faster than cars in city traffic which is why
couriers use them.
Helmut Wabnig
LEDs containing Arsen (galliumarsenide) will cause the
NHS "Napoleon St. Helena Syndrome" by As-poisoning.
Symptoms are: senility.
Side note:
Napoleon's green As-contaminated wallpapers were made
by a German manufacturer. Justice at last.
(Napoleon died of stomach cancer).
w.
Clive George
news:b1482fc0-b516-42fa...@b15g2000yqd.googlegroups.com...
I think you'll find you're agreeing with Pete :-)
Tim McNamara
<126f2384-ca8d-4230...@f18g2000prf.googlegroups.com>,
me <dhm_at_be...@yahoo.com> wrote:
> On Dec 7, 1:30�am, Peter Clinch <p.j.cli...@dundee.ac.uk> wrote:
>
> > me wrote:
> > > It's obvious that the mundane "white" LED bicycle lights do not
> > > light up the asphalt roads very well. �Incandescents, halogens,
> > > and sodium lights do better.
> >
> > Oh. �Last week I had the chance to compare a well respected halogen
> > lamp (BuM Lumotec Oval) to a well respected LED lamp (BuM IQ Fly)
> > on the same (unlit, asphalt) road at the same time, both running
> > from dynoubs on side by side bikes, and the IQ Fly did a damn site
> > better job of lighting it up.
> >
> > So obvious to some, perhaps, but not me.
> >
> > Pete. --
>
> ok,
>
> So it looks like I'll have to to some unbiased testing. It will take
> a while. <snip>
>
> I figure I'll eventually shoot around 50 still pix. I might add a
> set of fluorescent light pix. I suppose I'll web it up eventually.
Most of this has been done already. Why try to reinvent the wheel?
Comparing LEDs with halogens for bike lights, the current LEDS have
already surpassed halogens and will continue to improve. Halogens are a
mature technology and unlikely to improve significantly in this
application.
The photos are on the Web already. Google around. Start with Peter
White Cycles; Peter has posted quite a few comparison photos.
Tim McNamara
<829bdc28-9a18-4173...@j19g2000yqk.googlegroups.com>,
Ron Peterson <r...@shell.core.com> wrote:
507 nm for rods, 555 nm for cones. Blue is 475 nm, green is 500 nm and
yellow is 575 nm. Rods are most sensitive to green light.
Tom Keats
I'm quite happy w/ my old-school generator + Union headlight,
supplemented a little with flashlight battery lights.
It is enough. A lead/acid murdercycle battery would
be overkill in terms of power o/p, let alone environmental
concerns when the damned thing is ready to be discarded.
The venerable Union headlight still works well because of
its intelligently designed Fresnel(ish) lens + reflector,
and the broad disc of light it emits.
New technology isn't always better technology. A lot
of times, predecessors have already figured things out
for us, that continue to work quite well. In that vein,
I guess posterity needs us contemporaries to figure out
how to make LEDs work best for 'em -- if indeed It Is
Written that posterity will only have LEDs at their avail.
Frankly, when riding at night, I don't even want to
turn night into day. That's not what bicycles are for.
Adaptation requires artfulness & finesse, not the
Brute Force & Ignorance impinged by the ongoing quest
for "better/stronger/brighter," and for technologies
that do our brainwork for us.
Ron Peterson
> Ron Peterson <r...@shell.core.com> wrote:
> > The rods of the eye are most sensitive to blue light.
> 507 nm for rods, 555 nm for cones. Blue is 475 nm, green is 500 nm and
> yellow is 575 nm. Rods are most sensitive to green light.
Thanks for the correction. I should have said that rods are sensitive
to shorter wavelengths than the cones.
--
Ron
Androcles
Then what the heck are you whining about blinking lights, speed
difference, positioning on the street and fading batteries for in
a sci newsgroup, Mr. Oh-so-happy? You are all set, get on your
bike and ride outa here on the horse you rode in on.
Autymn D. C.
> "Mr. Benn" <%...@invalid.invalid> wrote in message
> news:hfdslf$ghr$1...@news.eternal-september.org...
> > Brendan Gillatt <brendanREMOVET...@brendanREMOVETHISgillatt.co.uk> wrote
> > in
> >news:7dqdnRJKOqR5_ofW...@pipex.net:
> >> That is an unfair comparison--the _light_ power output of a halogen bulb
> >> is much less than a modern LED for the same electrical power input.
>
> > The latest LEDs from Cree now produce more than twice the amount of light
> > that a compact fluorescent tube (CFT - otherwise know as an energy-saving
> > lamp) produces for the same amount of electrical power. CFTs produce
> > around 3-4 times the light of a halogen lamp.
>
> The latest fireflies from Nature now produce more than a million times the
> amount
> of light that a compact LED produces for even less electrical power.
Their elèctrical power is what?
datakoll
lamp, of different manufacture, mounted low on the forks.
Dave Larrington
Tim McNamara <tim...@bitstream.net> tweaked the Babbage-Engine to tell us:
> Most of this has been done already. Why try to reinvent the wheel?
> Comparing LEDs with halogens for bike lights, the current LEDS have
> already surpassed halogens and will continue to improve. Halogens
> are a mature technology and unlikely to improve significantly in this
> application.
>
> The photos are on the Web already. Google around. Start with Peter
> White Cycles; Peter has posted quite a few comparison photos.
See also:
http://picasaweb.google.co.uk/grahamglen0/LightTesting#
--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
A complimentary biro(tm) is /not/ to be sniffed at.
Autymn D. C.
> "Tom Keats" <tkeats2...@hotmail.com> wrote in message
> news:jpevfh...@news.eternal-september.org...
> > There seems to be a mindset that that is indeed what
> > bike riders need to do, either in terms of o/p wattage
> > or brightness. In city traffic, blinking lights + speed
> > difference + positioning on the street does the trick
> > nicely -- as long as the batteries don't fade.
Post at nesci.physics instead then.
> So get a lead-acid battery from a motor-cycle.
> The weight won't affect your speed, just your acceleration,
> and when you get tired pedalling you can run a motor from
> it. Electrically propelled bicycles have been around for a while
> now.
> Anyway, bikes are faster than cars in city traffic which is why
> couriers use them.
Weiht affects both, and bikes are freer than cars, not faster.
Autymn D. C.
> LEDs containing Arsen (galliumarsenide) will cause the
> NHS "Napoleon St. Helena Syndrome" by As-poisoning.
>
> Symptoms are: senility.
>
> Side note:
> Napoleon's green As-contaminated wallpapers were made
> by a German manufacturer. Justice at last.
> (Napoleon died of stomach cancer).
Any way you say thet, arse-poisoning or ass-poisoning, is freaken
funny.
Autymn D. C.
> In article
> <829bdc28-9a18-4173-ad3a-72574d550...@j19g2000yqk.googlegroups.com>,
dissenty? {{cn}}
Tom Keats
"Autymn D. C." <lysd...@sbcglobal.net> writes:
> On Dec 12, 3:43�am, "Androcles" <Headmas...@Hogwarts.physics_q> wrote:
>> "Tom Keats" <tkeats2...@hotmail.com> wrote in message
>> news:jpevfh...@news.eternal-september.org...
>> > There seems to be a mindset that that is indeed what
>> > bike riders need to do, either in terms of o/p wattage
>> > or brightness. �In city traffic, blinking lights + speed
>> > difference + positioning on the street does the trick
>> > nicely -- as long as the batteries don't fade.
> Post at nesci.physics instead then.
I'm posting at rec.bicycles.misc. If you don't like r.b.m
perhaps you should filter it in your newsreader.
The crossposting inflicted by the original post is neither
my fault nor my responsibility to rectify, so long as folks
from crossposted newsgroups (such as yourself) decide
to respond.
>> So get a lead-acid battery from a motor-cycle.
>> The weight won't affect your speed, just your acceleration,
>> and when you get tired pedalling you can run a motor from
>> it. Electrically propelled bicycles have been around for a while
>> now.
>> Anyway, bikes are faster than cars in city traffic which is why
>> couriers use them.
> Weiht affects both, and bikes are freer than cars, not faster.
So you indeed /are/ interested in r.b.m topics.
And FYI, bikes often are faster than cars in city traffic.
Androcles
to respond to one of my posts.
Tom Sherman °_°
> [...]
> I plonked that silly bitch years ago, it's still stupid enough
> to respond to one of my posts.
>
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Tom Sherman - 42.435731,-83.985007
I am a vehicular cyclist.