Re: Strange problem with low energy light bulb

[Lostgallifreyan]

[email protected] (Don Klipstein) wrote in

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 was trying to keep the lumens out of this entirely, but I'll buy it.
It makes me wonder what the fuss is about actually. While it's better to
get more efficiency, it seems that incandescents aren't so bad we need to
consider banning them, we just need to think more about what source we use
for a given task. As for the case to ban all but halogen types, how much
might be gained? With IR reflection to make them keep the tungsten hotter
for a given input, we get more light, but even so, is there that much
difference? Enough to say that they stay and standard incandescents go?

If LED's ever get a spectral match for a small efficient low-volt halogen,
at least the choice will be easy.

 

[Albert Manfredi]

First, how can a hotter temperature be cold??

Sunlight at high noon is considered "cold" lighting, even though the
temperaure of the light is at its highest. It's just semantics.

I bet we could get used to 'cold' light plenty fast so long as we
weren't
actually cold ourselves.

I doubt anyone prefers indoor lighting at 6500 K during a summer night.
It's stark lighting regardless.

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.

Disagree. I think the bleakness Dickens refers to in this example is
unrelated to color temperature.

Bert

 

[Arfa Daily]

[email protected] (Don Klipstein) wrote in


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.

I suspect that your liking of odd colour schemes, harps back to distant
memories of your early life on Gallifrey, with its twin low luminosity suns,
and before you became 'lost' ... ;~}

Arfa

 

[Lostgallifreyan]

I suspect that your liking of odd colour schemes, harps back to
distant memories of your early life on Gallifrey, with its twin low
luminosity suns, and before you became 'lost' ... ;~}

Yes, yes that would be it. > The high council didn't build the Panopticon
for nothing, you know... All those lights in the dark, hypnotic.

 

[Lostgallifreyan]

Disagree. I think the bleakness Dickens refers to in this example is
unrelated to color temperature.

That was the point. Don't you see? That's exactly why it isn't the colour
temperature that really defines our reactions at all, it's the context.

 

[Lostgallifreyan]

Sunlight at high noon is considered "cold" lighting, even though the
temperaure of the light is at its highest. It's just semantics.

Semantics? As in the usual current usage meaning 'empty meaning, splitting
hairs'? That's only true if you ignore context. That's what gives it
meaning. No-one in their right mind would consider high noon in the outback
to be 'cold' either literally OR figuratively.

 

[Arfa Daily]

[email protected] (Don Klipstein) wrote in


I was trying to keep the lumens out of this entirely, but I'll buy it.
It makes me wonder what the fuss is about actually. While it's better to
get more efficiency, it seems that incandescents aren't so bad we need to
consider banning them, we just need to think more about what source we use
for a given task. As for the case to ban all but halogen types, how much
might be gained? With IR reflection to make them keep the tungsten hotter
for a given input, we get more light, but even so, is there that much
difference? Enough to say that they stay and standard incandescents go?

If LED's ever get a spectral match for a small efficient low-volt halogen,
at least the choice will be easy.

OK, I'm following all this - just about, I think. So let me now throw in a
slightly new set of questions. Back to LED halogen substitutes. Some
distance back up the thread, consideration was being given to losses in the
control circuitry for the LEDs. So, the first question is, just exactly how
are these things ballasted ? The reason that I ask this is that I was in an
electrical cash and carry warehouse tonight, and I picked up a couple of
LED-based GU10 replacements to have a look at. I didn't count the actual
LEDs, but I'm guessing at about 15 or so - let's say 15. Let's also say that
they are bluish types and let's guess at a forward drop of 4 volts. With
them all in series, that's going to be around 60v DC that's needed to run
them.

Now, these lamps were of exactly the same dimensions as a standard GU10
lamp, with the same 'nail head' pins, set in the identical ceramic base.
240v AC rating, stated on the packet. The glass 'cone' was exactly the same
as on a standard GU10, and it appeared, as far as I could see, that for the
most part, it was filled with the LEDs, which looked like 5mm types, and
their support plate. So that leaves very little space for any drive
electronics - certainly not a switch mode PSU, or even for a smoothing cap
on the end of a simple reccy / resistor combination. Not that there would
have been room even, for a resistor of a sufficient power rating to handle
this kind of drop.

Next question. There were two types on offer, one rated at 1 watt, and one
at 1.3 watts, both with a quoted lifetime of 50k hours. So what exactly is
being said here ? Is that 1 watt input from the mains supply, or 1 watt used
by the LEDs or 1 watt of visible luminous output power ? A website that I
looked at quoted the output of a 0.62 watt one, at 20-30 l - I'm assuming
that to be 'lumens'. If correct, and not a misprint, that seems to be a
piddling amount compared to the 950 lumens quoted for an incandescent 240v
50 watt GU10, and yet the text suggests that they are only 'slightly
dimmer'. It also says that these lamps give off almost no heat, and that
they consume only around 10% of the energy of a conventional equivalent
halogen GU10. So for a 50 watt type, that's about 5 watts, suggesting that
around 4 watts is lost in ballasting ??

Setting aside the issues of colour temperature and CRI, which I am sure will
shortly be overcome, it seems to me that these halogen replacement lamps are
even now on their way to bettering CFLs in that they are already exactly the
same pattern as the lamps that they are replacing, so must have sorted the
ballasting problem. And yet there are no plans to phase out the incandescent
version. This flies directly in the face of the proposals to ban standard
incandescents, when the advocated replacement technology (CFLs) is far from
being a satisfactory replacement, on several counts.

Arfa

 

[Arfa Daily]

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

Don'cha just hate the way they swing from blue through stark white to green,
when they come round a bend in front or behind you ... Also, having sat
behind some, the perceived ability to light the road, does not seem to be
any better than halogens, which may again come down to colour temperature
and the human vision comfort zone.

Arfa

 

[Mr.T]

In which way are they 'inaccurate'? They will look wrong to the eye on a
'cut' but as with real life if all shots are matched the eye will
accommodate.

Not so. They ARE wrong. The relative densities of the individual film layers
will be quite innacurate when exposed with the wrong light.

The monitor you're reading this on is unlikely to match
*exactly* another one in colour temperature but will look ok to the
individual. The eye compensates, as I said, as it must do given that
daylight changes. Unless it has a reference to match to.

Which is everything else within your field of view. Only if *everything*
changes will the *brain* correctly compensate.

Err, yes. That's what I said. But it doesn't react instantly. Hence it
notices a sudden change in colour temperature. Like switching on 4500K
lights in a house when it gets dark.;-)

So a couple of minutes readjustment is abhorent to you?
Doesn't bother me too much.

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

No, as I already stated it was simply conditioning from fires, candles, oil
lamps and tungsten filament globes.
Have you ever wondered why people aren't bothered by the change from
daylight, or in fact are able to wear coloured sun glasses, but can readily
pick an off balance color photo?

MrT.

 

[Mr.T]

Moonlight's color temperature at its highest is about 4000.

I haven't seen a reference for this, but even assuming it is so, it's still
higher than many people here prefer it would seem.

Meanwhile, at illumination level so low that color vision does not work
well, color temperature matters less. At illumination levels an order of
magnitude or two or three above that of moonlight, most people like it
warm (lower color temperature).

Which is my point. People simply prefer something, then try to introduce
pseudo scientific rationalisation to claim anybody who disagrees with them
is wrong.

MrT.

 

[Don Klipstein]

Not so. They ARE wrong. The relative densities of the individual film layers
will be quite innacurate when exposed with the wrong light.


Which is everything else within your field of view. Only if *everything*
changes will the *brain* correctly compensate.


So a couple of minutes readjustment is abhorent to you?
Doesn't bother me too much.


No, as I already stated it was simply conditioning from fires, candles, oil
lamps and tungsten filament globes.
Have you ever wondered why people aren't bothered by the change from
daylight, or in fact are able to wear coloured sun glasses, but can readily
pick an off balance color photo?

An off-balance color photo has its surroundings as a color reference.
It would be like having colored sunglasses coloring only a small portion
of your field of vision.

- Don Klipstein ([email protected])

 

[Mr.T]

An off-balance color photo has its surroundings as a color reference.

Which is what I said already. That was my point.

MrT.

 

[Lostgallifreyan]

I haven't seen a reference for this, but even assuming it is so, it's
still higher than many people here prefer it would seem.

Nice way to test: Take a camera and tripod, do a long exposure shot of a
moonlit scene. Then view the phtot on a monitor in a context you know. I
haven't done this but I think it will bear out the claim that the moon's
light is brownish, as it looks when you look directly at it. The blue comes
from a combination of scattered light and scotopic sensitivity to the blue
part of its spectrum.

 

[Laurence Payne]

Nice way to test: Take a camera and tripod, do a long exposure shot of a
moonlit scene. Then view the phtot on a monitor in a context you know. I
haven't done this but I think it will bear out the claim that the moon's
light is brownish, as it looks when you look directly at it. The blue comes
from a combination of scattered light and scotopic sensitivity to the blue
part of its spectrum.

You may well be right. But I wouldn't rely too heavily on the colour
accuracy of a long exposure

 

[Arny Krueger]

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

There many kinds of preferences. One is the preference for that which is
traditional and familiar, and another is the preference for that which is
most effective for the purpose at hand.

I've found that if the goal is reading accurately with limited light, then
higher temperatures even 5000 degrees and up, can be preferable. I've read
far into many a dark fall or winter evening in a tent, using a pretty blue
LED headlamp.

I did some tests of people reading Bibles and hymnals which tend to small
print, in a congregational setting with fairly high light levels, and found
that my readers were most comfortable with color temperatures in the 3200
degree range.

I suspect that preferences for color temperatures below 3200 degrees are
heavily influenced by tradition and past experience.

 

[Lostgallifreyan]

You may well be right. But I wouldn't rely too heavily on the colour
accuracy of a long exposure

I guess not. Probably weighted by gamma correction or something. Worth
trying a few different timings to see what happens though. Maybe with some
small faint diffused blackbody source in frame as a reference.

Apart from correction added, there is no reason for colour to fail, because
photons are quanta, each one will be treated the same by filters no matter
how few or how many. The real danger is overexposure saturating any of the
filtered sensors.

 

[Lostgallifreyan]

The real danger is overexposure saturating any of the
filtered sensors.

Sorry, that's daft. It's modelled. But if you have enough the camera
adds them up and the values can clip, which amounts to same thing.

 

[Lostgallifreyan]

There many kinds of preferences. One is the preference for that which
is traditional and familiar, and another is the preference for that
which is most effective for the purpose at hand.

I've found that if the goal is reading accurately with limited light,
then higher temperatures even 5000 degrees and up, can be preferable.
I've read far into many a dark fall or winter evening in a tent, using
a pretty blue LED headlamp.

I did some tests of people reading Bibles and hymnals which tend to
small print, in a congregational setting with fairly high light
levels, and found that my readers were most comfortable with color
temperatures in the 3200 degree range.

I suspect that preferences for color temperatures below 3200 degrees
are heavily influenced by tradition and past experience.

Yes. Been saying similar stuff here last night. Also, quite apart from
preference and convention and all that, there is a stark fact that we use
shortwave light to resolve fine detail without strain. That's a basic
physical fact. So it makes NO sense at all to suggest that reading is best
done in a low colour temperature. Same goes for any other detailed small
scale activity such as most indoor hobbies involve.

The only reason we need bright incandescent to read by is that it is the
ONLY way we can get enough shortwave light. I've found that so long as you
have a decent continuum such as the newer Cree Xlamps have, and a tint that
favours the long end, such as the WG tint, you can be comfortable with much
lower lumen counts than when using low colour temperatures. This is exactly
what many here said was 'dreary' or similar, but I tried it last night. I
went outside to see the orange light in the clouds over the city, the many
tungsten lamps all around in windows, waited till I was thoroughly
adjusted, then went inside. Far from looking dreary, it was invitingly
bright and easy to see things by, and this was ONE single emitter aimed at
the ceiling. It had the same cosy quality that a pressurised paraffin
(kerosene) lamp has in a country kitchen during a power cut. I remember
that well enough, and this new light was similarly pleasing, if a little
different, sharper perhaps.

 

[Dave Plowman (News)]

Not so. They ARE wrong. The relative densities of the individual film
layers will be quite innacurate when exposed with the wrong light.

You conveniently snipped the part about video. And a daylight film can
also look 'wrong' when taken in daylight of the wrong colour temperature.
Which can be corrected by filters when taking the pic or processing it.

Which is everything else within your field of view. Only if *everything*
changes will the *brain* correctly compensate.

Not so - do you change the colour temperature of your TV or monitor
according to the ambient light? The brain focuses on the important part
after time - within reason.

So a couple of minutes readjustment is abhorent to you?
Doesn't bother me too much.

Fine - but you're in a minority if you like cold domestic lighting.

No, as I already stated it was simply conditioning from fires, candles,
oil lamps and tungsten filament globes.

Fluorescent lights have been around for a long, long time. And early ones
were all cold compared to tungsten. People could easily have got used to
them for domestic light, but very few chose to.

Have you ever wondered why people aren't bothered by the change from
daylight, or in fact are able to wear coloured sun glasses, but can
readily pick an off balance color photo?

Can they? Depends on their skills. Have you never noticed how many people
are happy with a TV where the grey scale is miles out?

 

[Dave Plowman (News)]

I suspect that preferences for color temperatures below 3200 degrees are
heavily influenced by tradition and past experience.

Perhaps if it were only working light. But at home it's usually comfort
light.