"white" LED's vs. incandescent and halogen lights

In article ,
"Androcles" writes:

"Peter Cole" wrote in message
...
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).
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,
halogens, and sodium lights do better.

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

In article
,
" wrote:

On Dec 5, 8:26Â*pm, Michael Press wrote:
In article
,



" wrote:
On Dec 4, 2:50Â*pm, me wrote:
It's obvious that the mundane "white" LED bicycle lights do not light
up the asphalt roads very well. Â*Incandescents, halogens, and sodium
lights do better. Â*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. Â*The blues are voltage induced while the y-
o-r's are secondary from phosphors in the casing. Â*Therefore to help
refine my question,

1. Â*Do the stronger blues in the LED cause the weaker yellow/orange/
reds to be less perceived?

Â* "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.

Â* 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.

(sigh)

Read the whole thread.

I read it. The human eye is not more sensitive to red.

--
Michael Press

Androcles 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.

A whole brain gives a different impression.

"Peter Cole" wrote in message
...
Androcles 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.

A whole brain gives a different impression.

Ok, so you hallucinate that a ****y little Xmas tree light
is brighter than a sodium or mercury vapour street light.
Get your local authority to install them on lamp posts.

*plonk*

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On Sun, 6 Dec 2009 22:35:44 -0000, "Androcles"
wrote:

*plonk*

Seems that "Androcles" is a total plonker. Who'd have thought it.

Guy
--
http://www.chapmancentral.co.uk/urc
GPG public key at http://www.chapmancentral.co.uk/pgp-public-key.txt

DougC wrote:

It is easy to forget--but if you compare a LED flashlight to an
"old-fashioned" incan flashlight, you can see how far off the color
balance of the LED is (in spite of the LED appearing to be much
brighter).

What I think is, "wow, I used to consider this pitiful yellow Maglite
to be pretty badass."

Thinking back to the bad old days, I remember using very expensive
indoor photography light bulbs with lifespans measured in tens of
hours. They were overdriven in the attempt to raise their color
temperature a little bit above dull yellow. And the attempt was only
partly successful, considering that you still had to use color-biased
"Tungsten" film to get naturalistic color rendering. A continuous
spectrum is not the same thing as a good one! It has to be pretty
continuous and pretty white, too.

I use 3500-4100K compact fluorescents all over my house now, and the
occasional incandescent bulb is a living reminder of a time when
streetlights were green and house lights were miserable.

Chalo

Peter Cole 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.

That's not at all obvious to me.

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

On Dec 6, 8:32*pm, Chalo wrote:
Peter Cole 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.

That's not at all obvious to me.

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

Careful, Chalo! "Androcles" may plonk you. And I'm sure that will
bother you just as much as it bothered me! ;-)

- Frank Krygowski

Androcles wrote:
"Peter Cole" wrote in message
...
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).
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,
halogens, and sodium lights do better.


Would it be possible to have more than one LED light but with different
filters in - red and green - to pick out some of the lumpy bits?


--
Its never too late to reinvent the bicycle

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.
--
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 http://www.dundee.ac.uk/~pjclinch/