Re: Strange problem with low energy light bulb

[Lostgallifreyan]

[email protected] (Don Klipstein) wrote in

Yes, quite true. But at full voltage most 120V incandescents 60
watts
or more are about 4.5-8% efficient at converting electricity to
radiation in the 400-700 nm range.

Is this by calculation or measurement? I was hoping you or someone else
would comment on that from experience with it. Those lower figures are so
common that they must have come from somewhere, and not all from looking
only at the strongest wavelength or omitting something in calculation. I've
never seen claims of 6 to 7% for a 100W lightbulb before, and I'm sure I
would if measurements routinely reported it.

 

[Lostgallifreyan]

[email protected] (Don Klipstein) wrote in

I have been happier with the color rendering of CFLs than that of
most
white LEDs. I have found most white LEDs to make reds and greens
appear duller. I have also seen the color-dulling effect of most
fluorescents with color rendering index outside the range of 82-86
(though high is better than low). The key here appears to be ratio of
yellow content to red and green content.

There is a sharp dip in green in the LED's. I agree it's not nice, nor is
the muted red. It's still a continuum though, and if improved will be
extremely easy to live with. Right now it's almost discontinous because the
dip is so great, but the discontinuity in CFL's seems very un-natural to
me, I notice it especially if I'm carrying something brightly coloured
between rooms. There's an almost disturbing 'filtration' effect on the
various colours. Some of my CFL's are way too heavy in red too. It's not a
pleasant colour, it's sickly, it makes normally innocous marks like pine
resin under pain on wood look like inflamation on diseased skin.

I don't think the key is any specific colour absence or presnce, but the
presence of any sharp absence. CFL discontinuities drop out like digital
bits, but those of LED's are like analog curves, and inherently easier to
compensate for.

 

[Albert Manfredi]

Have you never wondered why most prefer the colour temperature of
tungsten
for domestic lighting?

It's not tungsten we prefer, I don't think, but rather a color
temperature that's close to that of a flame. That's what the human race
used for artificial lighting for the very vast majority of its
existence. It shouldn't be surprising that we still find it more comfy
than cold lighting, at night.

My warmest CFLs are now 2700 K. Not bad, but I'd still prefer a little
warmer. The 4100 tube fluorescents we have are not in the least
attractive.

Don Pearce posted this:

Nice chart here

http://www.olympusmicro.com/primer/lightandcolor/colortemp.html

Candlelight is 2000 K
60W incadescent bulbs are about 2500 K.
100W are slightly cooler, but still well under 3000 K.
Photofloods, which seem quite cool, are around 3500 K.

Nor surprising that something up around 6000 K would be annoying.

Bert

 

[Lostgallifreyan]

[email protected] (Don Klipstein) wrote in

More like 6-7%. Each watt of tungsten radiation in the 400-700 nm
range
is around 250 lumens.


Figure around 250-300 lumens per watt of "white LED light". Looks
like
those achieve about 20%.

Watts of emitted light? I just saw a later post of yours that mentioned
"lumens per visible radiated watt". I think that's why we're discussing
such different values. I'm talking about input watts. I thought we all
were, at least Eeyore certainly was, as that's ultimately watt (haha) is
consumed no matter watt is emitted.

Cree themselves don't claim anything like 250-300 l/W for input watts, at
least not yet, though that might not be long awaiting.

So how does a 100W incandescent look in that context?

 

[Lostgallifreyan]

[email protected] (Don Pearce) wrote in

Workshops are a different thing - they aren't really a domestic
environment.

Mine is. And the variety of lights I use in it amazing, at times.
Usually incandescent though, when resting.

 

[Lostgallifreyan]

Have you never wondered why most prefer the colour temperature of
tungsten for domestic lighting?

Familiarity, and because it embodies a kind of neat simple magic, a safe
capturing of fire in an idealised form. It's a scientific form that almost
everyone can grasp. It's as iconic as the wheel, it's just not been around
as long.

I guess the truth of 'natural daylight' emulations is that they make people
feel agoraphobic if they can't withdraw from that light. Bring on LED
colour mixing. Or at least a nice emulation of firelight.

 

[GregS]

It's not tungsten we prefer, I don't think, but rather a color
temperature that's close to that of a flame. That's what the human race
used for artificial lighting for the very vast majority of its
existence. It shouldn't be surprising that we still find it more comfy
than cold lighting, at night.

My warmest CFLs are now 2700 K. Not bad, but I'd still prefer a little
warmer. The 4100 tube fluorescents we have are not in the least
attractive.

Most CFL's I have used are too orange for me. I have one of those bargain dollar store
blue ones, and those suck. I bought one at The home Depot many years ago.
paid $20 for a dimmable type. It ended up being the best color I have seen, in my
opinion. They quit selling dimmable lamps. I hate when stores change stocks all
the time, especially Wal Mart.

greg

 

[Lostgallifreyan]

[email protected] (Don Klipstein) wrote in

1. The spectrum is richer in wavelengths favorable to scotopic
vision, which lacks ability to see color. Higher color temperature
favors things looking grayish when illumination level is down to
several lux or less.

2. More light of wavelengths favorable to scotopic vision can make
your eye's pupil smaller than otherwise for a given illumination
level. 100 lux at 5000 K can make your pupil smaller than 100 lux at
3000 K. (The lux and other photometric units are defined in terms of
photopic vision and not scotopic vision.) That can make things appear
dimmer. This can also have an effect on color vision if illumination
level is down to a few lux or less, by depriving the color-sensing
cones of light.

3. Reds look darker at higher color temperature, and can "drop out to
black" when color temperature is high and illumination level is low
enough to start making photopic vision marginal.

All true, but balanced perfectly, whatever the explanations might be, by
the sense of utter dinginess that a dim incandescent or red-heavy CFL
makes. Whether a spectrum favours photopic or scotopic vision, it looks
dire if we have to make an effort to perceive colour and space with it. I
think that the drain on our effort is partly what causes drear. That and a
lack of contrast, which might account for the feeling even in high daylight
illumination. I like LED's better than CFL's because they allow more
natural contrasts, if shone on white paint they are like sky, if direct,
they are like sunlight (though lacking in colour balance). CFL's don't
manage either convincingly at all, I find.

 

[Don Klipstein]

[email protected] (Don Klipstein) wrote in


Is this by calculation or measurement? I was hoping you or someone else
would comment on that from experience with it. Those lower figures are so
common that they must have come from somewhere, and not all from looking
only at the strongest wavelength or omitting something in calculation. I've
never seen claims of 6 to 7% for a 100W lightbulb before, and I'm sure I
would if measurements routinely reported it.

They do lots of photometric measurements, while radiometric figures for
incandescents appear to me to be rather rare. More common than actual
measurements I see comments in the direction of "close enough to
blackbody".

http://www.uwsp.edu/cnr/WCEE/keep/Mod1/Rules/EnConversion.htm
says most incandescents are about 5% efficienct

http://www.iiasa.ac.at/Publications/Documents/IR-04-027.pdf
also gives a 5% figure

Osram says 5% here:
http://catalog.osram-os.com/catalogue/catalogue.do;jsessionid=
337BCEEB510F317E25E607F73C895CFB?act=downloadFile&favOid=
020000020003caf0000100b6

http://www.healthyhomemagazine.ca/light.html
says 4-6%, attributed to someone at Natural Resources Canada.

http://www.eia.doe.gov/kids/energyfacts/saving/efficiency/savingenergy.html
says 10%

http://oikos.com/esb/40/kitlight.html says 10%

10% I find to be a somewhat common figure, though rather optimistic.
Some of those 10% figures may be based on an alternative definition of
visible light as 380-760 nm rather than 400-700 nm.

- Don Klipstein ([email protected])

 

[Don Klipstein]

[email protected] (Don Klipstein) wrote in


Watts of emitted light? I just saw a later post of yours that mentioned
"lumens per visible radiated watt". I think that's why we're discussing
such different values. I'm talking about input watts. I thought we all
were, at least Eeyore certainly was, as that's ultimately watt (haha) is
consumed no matter watt is emitted.

Cree themselves don't claim anything like 250-300 l/W for input watts, at
least not yet, though that might not be long awaiting.

So how does a 100W incandescent look in that context?

I am saying that a watt of white light is about 250 lumens, not the 683
some use as the lumen/watt figure for a 100% efficient light source. A
100% efficient white light source would achieve about 250-300 or so
lumens/watt, depending on what they call "white".

Most of those generating figures of incandescents being 1-2% efficient
are assuming that they would achieve 683 lumens/watt if they were 100%
efficient.

- Don Klipstein ([email protected])

 

[Dave Plowman (News)]

It's not tungsten we prefer, I don't think, but rather a color
temperature that's close to that of a flame.

Err, isn't that what I wrote? It's the colour temperature that matters
rather than the source.

 

[Lostgallifreyan]

[email protected] (Don Klipstein) wrote in

I am saying that a watt of white light is about 250 lumens, not the
683
some use as the lumen/watt figure for a 100% efficient light source.
A 100% efficient white light source would achieve about 250-300 or so
lumens/watt, depending on what they call "white".

Most of those generating figures of incandescents being 1-2%
efficient
are assuming that they would achieve 683 lumens/watt if they were 100%
efficient.

- Don Klipstein ([email protected])

Ok, I see that lumens depend on the spectrum, not just the actual visible
watts emitted, but given that there is convection in an incandescent lamp
that makes some of its power emit in the IR, does enough leave that way to
bring the lumens per input watts down to levels that can account for stated
line-power-to-light efficiences of 3% and lower?

I think when Cree talk of lumens per watt, they're talking of lumens for
each watt of electrical input, and that's how I want to make the
comparison.

 

[Don Klipstein]

[email protected] (Don Klipstein) wrote in


Ok, I see that lumens depend on the spectrum, not just the actual visible
watts emitted, but given that there is convection in an incandescent lamp
that makes some of its power emit in the IR, does enough leave that way to
bring the lumens per input watts down to levels that can account for stated
line-power-to-light efficiences of 3% and lower?

Most of the output of an incandescent is IR.

I think when Cree talk of lumens per watt, they're talking of lumens for
each watt of electrical input, and that's how I want to make the
comparison.

I was only mentioning figures of lumens per watt of visible light output
to explain that an incandescent achieving 17.1 lumens per input watt is
nearly 7% efficient.

Put 100 watts into an incandescent that chieves 17.1 lpw. You get 1710
lumens. Each lumen is about 1/250 watt of "white light", not the 1/683
watt assumed by those claiming incandescents are only 1-2% efficient.

- Don Klipstein ([email protected])

 

[David Harmon]

On Wed, 11 Jul 2007 15:10:28 +0000 (UTC) in sci.electronics.basics,
[email protected] (Don Klipstein) wrote,

Personally, I like more like 3500K at most brighter indoor lighting
levels, closer to 3,000 for dimmer indoor lighting.

Higher color temperature often appears "dreary" unless illumination
level is very high.

Do you put orange gels on your windows?

 

[Albert Manfredi]

Err, isn't that what I wrote? It's the colour temperature that matters
rather than the source.

Well, you wrote may things, including this:

"Lighting which is used to replace daylight - like that most of us have
at home for use when daylight fades - ideally shouldn't give such a
sudden change in temperature that it is noticeable. In the same way as
lighting used to supplement daylight - like in say an office - should
also be an approximate match to that daylight. It's common sense,
really."

I do agree that if we are supplementing daylight, e.g. in work spaces
with large windows during the day, rather than providing lighting at
night, a cooler light (hotter temp) is probably preferable. But for
night time lighting, I think what we are looking for is the color of
flame.

I'm saying, it's not that we are conditioned to the color of tungsen,
it's that we are looking for something close to 2000 K at night. Much
cooler cooler light than that (higher temp) is stark and generally
unpleasant.

By the way, this also applies to xenon headlights in some cars. They are
superbly obnoxious at night, to other drivers. Even if they aren't
brighter than halogens, the bluish color is very distracting.
Fortnunately, there seem to be fewer of the really annoying ones around
these days. Maybe the auto makers got too many complaints.

Bert

 

[Lostgallifreyan]

[email protected] (Don Klipstein) wrote in

Most of the output of an incandescent is IR.

What I meant was, might more heat be carried away by the convection in the
argon fill, and be either conducted or radiated away at far longer
wavelengths? I mentioned convection specifically to be clear I'm not
talking about directly radiated energy.

I was only mentioning figures of lumens per watt of visible light
output
to explain that an incandescent achieving 17.1 lumens per input watt
is nearly 7% efficient.

Put 100 watts into an incandescent that chieves 17.1 lpw. You get
1710
lumens. Each lumen is about 1/250 watt of "white light", not the
1/683 watt assumed by those claiming incandescents are only 1-2%
efficient.

I've managed unintentionally to get you to say that three times now.

I'm not always quick on the uptake, but I try... what I'm getting at, is
can any other evaluation result in that lower figure? I'm not convinced
that taking only the lumens at 555 nm accounts for this. Lumens seem
slippery enough if they depend on spectra and photopic sensitivity anyway.

Wikipedia again:
"In photometry, luminous flux or luminous power is the measure of the
perceived power of light. It differs from radiant flux, the measure of the
total power of light emitted, in that luminous flux is adjusted to reflect
the varying sensitivity of the human eye to different wavelengths of
light."

I guess that much can be relied on. So try it this way:

Take a 100W incandescent, and a large ellipsoidal mirror to gather as much
of its radiant flux as you can, throwing it to the other focus of the
ellipse where a black painted thermopile awaits. The incoming light is
passed through a dichroic filter at 700 nm to send the IR elsewhere and
pass only the visible light to the thermopile. Assuming you get close to
ideal light gathering for the visible wavelengths (and IR rejection), how
many watts will be read from the thermopile?

I understand that photometric measurements abount, and radiometric ones are
rarer, but that's what I want to look at, as without that grounding the
rest seems most insecure.

 

[Don Klipstein]

On Wed, 11 Jul 2007 15:10:28 +0000 (UTC) in sci.electronics.basics,
[email protected] (Don Klipstein) wrote,

Do you put orange gels on your windows?

No, I don't.

But if the light level is neither in kilolux nevels nor a recent uptick
from something lower, I find daylight to usually have no warmth or "cheer".

If the ceiling is dark but the windows are bright, then things can look
cheerful - sometimes - for some reason.

- Don Klipstein ([email protected])

 

[Lostgallifreyan]

I'm saying, it's not that we are conditioned to the color of tungsen,
it's that we are looking for something close to 2000 K at night. Much
cooler cooler light than that (higher temp) is stark and generally
unpleasant.

It is conditioning, but it's worth thinking about what the conditioning is.

First, how can a hotter temperature be cold?? The only way to account for
that is to look at the environment. Blue sky accepts radiant heat from the
earth so nights chill faster on clear evenings, pale light from the moon or
stars accompanies those same conditions within hours, and those sources are
so pale that we have scotopic vision to cope with them.

The whole thing is based on comfort. There is one exception to the usual
perception of cool faint lights. The whole midsummer night's dream idyll is
based on this, the almost magical inversion that allows a warm night to
make perception of these 'cold' lights seem something other than
threatening to our health.

I bet we could get used to 'cold' light plenty fast so long as we weren't
actually cold ourselves. Conversely, Dickens and many others have commented
on the bleakness of a small flame when there isn't enough heat to warm the
people who need it. It really has to do with our ambient conditions, not
direct colour perceptions at all.

 

[Don Klipstein]

[email protected] (Don Klipstein) wrote in


What I meant was, might more heat be carried away by the convection in the
argon fill, and be either conducted or radiated away at far longer
wavelengths? I mentioned convection specifically to be clear I'm not
talking about directly radiated energy.

As far as I understand what goes on there, around 10-15 watts is
convected from the filament in a 100 watt "USA-usual" "standard" A19.

I've managed unintentionally to get you to say that three times now.

I'm not always quick on the uptake, but I try... what I'm getting at, is
can any other evaluation result in that lower figure? I'm not convinced
that taking only the lumens at 555 nm accounts for this. Lumens seem
slippery enough if they depend on spectra and photopic sensitivity anyway.

Wikipedia again:
"In photometry, luminous flux or luminous power is the measure of the
perceived power of light. It differs from radiant flux, the measure of the
total power of light emitted, in that luminous flux is adjusted to reflect
the varying sensitivity of the human eye to different wavelengths of
light."

I believe some who are not aware that the lumen is a unit of luminous
and not radiant flux, or not aware of visible wavelengths other than 555
nm having less than 683 lumens per watt, divided a lumen/watt efficacy
figure by 683 to come up with incandescents being only 1-2% or 2.6%
efficient.

I guess that much can be relied on. So try it this way:

Take a 100W incandescent, and a large ellipsoidal mirror to gather as much
of its radiant flux as you can, throwing it to the other focus of the
ellipse where a black painted thermopile awaits. The incoming light is
passed through a dichroic filter at 700 nm to send the IR elsewhere and
pass only the visible light to the thermopile. Assuming you get close to
ideal light gathering for the visible wavelengths (and IR rejection), how
many watts will be read from the thermopile?

I expect about 6.7 watts in the case of a 1710 lumen 100W incandescent,
if the ellipsoidal mirror is a whole ellipsoid and 100% reflective and the
dichroic filter passes all 400-700 nm light.

As for the rest, approximately or "educated guesses":

UV passing through the glass: .12%
UV absorbed by the glass: .02%

Heat conducted/convected from the filament: ~13%

IR passing through the glass: ~60%
IR absorbed by the glass: ~20.16% ("rounded oddly" to make figures add to
100%)

I understand that photometric measurements abount, and radiometric ones are
rarer, but that's what I want to look at, as without that grounding the
rest seems most insecure.

- Don Klipstein ([email protected])

 

[Lostgallifreyan]

[email protected] (Don Klipstein) wrote in

But if the light level is neither in kilolux nevels nor a recent
uptick
from something lower, I find daylight to usually have no warmth or
"cheer".

If the ceiling is dark but the windows are bright, then things can
look
cheerful - sometimes - for some reason.

I mentioned contrast earlier, and I wonder if it might be this. I have an
odd colour scheme on my monitor, a kind of inversion of usual practise. I
call it 'panel lights'. It has black window objects, white and orange text
on them, the text backgound is a blue-biased mid grey, text black. Desktop
is deep blue with a pattern like dark water seen from a boat at twilight,
but saturated strongly, icon text there is like blue flame. Title bars are
green like plastic backlit by fluorescent light with red text. I like
programs with buttons that use colours well and illuminate like lights on
the black toolbars. Menus are yellow on a grey brown background. When
working on a full-screen text edit, it looks like a monochrome TV framed by
illuminated panels.

What I'm getting at is that this thing has both kinds of colour, 'hot' and
'cold', and most of all, strong contrasts. Some would find it as garish as
a fairground. I find it comforting the same way I find firelight
comforting. It keeps me calm yet aware for long periods while working.
Similar lighting tricks keep air pilots awake on night flights. (That's
partly the basis of the name I give that scheme).

Most colour schemes I see on computers are varieties of dark text on pale
backgrounds. I don't care if they're warm flamelike backgrounds or cool
fern greens and icy blues, I find them ALL distracting, stressful, and the
executive class adlanders white pages and thin grey text and pastel shades
are the very worst.

Ok, so I'm weird, but that's still a natural take on lighting. It shows
that there's a lot more to this than colour temperature. Contrast is
important too, as is the ratio of light to dark, and of object to space,
and suggestion plays a big part. It's very hard to be scientific about such
things, so maybe we shouldn't be trying too hard.

I'm still having a hard time adjusting to the fact that an SI unit, the
Lumen, is based on a statistical consensus, yet is placed alongside
hallowed units like the amp and the volt and the watt which seem as
immutable as 2+2 equalling four. Trying to get objective about what colours
are 'right' for us to accept and discussing it as if it is a hard science
is more weird to me than suggesting that the lightbulb is a form of magic.