On Sat, 19 May 2012 17:42:46 -0400, "Existential Angst"
wrote:

"Joseph Gwinn" wrote in message
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In article ,
"Existential Angst" wrote:

"Joseph Gwinn" wrote in message
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Ed Huntress wrote:

On Fri, 18 May 2012 22:28:32 -0400, "Existential Angst"
wrote:

"Ed Huntress" wrote in message
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On Fri, 18 May 2012 16:00:01 -0400, "Existential Angst"
wrote:

"Ed Huntress" wrote in message
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On Fri, 18 May 2012 15:29:22 -0400, "Existential Angst"
wrote:

"Ed Huntress" wrote in message
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On Fri, 18 May 2012 14:41:20 -0400, "Existential Angst"
wrote:

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in
message
news:XnsA0576C5905484lloydspmindspringcom@2 16.168.3.70...
"Existential Angst" fired this volley
in
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From 1996???? Holy ****, this sodium bulb I replaced
didn't
last
more than 2 years, operates about 7 hrs a day.
The brand I just bought is Plusrite. Do you recall the
brand
of
your
bulb? Does metal halide last longer than sodium?

Sodium lamps are quite a bit cheaper than metal halide.
--

Sodium lamps are a LOT cheaper than the sodium-ballasted
metal
halide
version. But, they last and last (on a good ballast).

The lamps I bought were industrial-quality GE lamps, and I
recall
the
400W lamps (sodium-ballast conversion variety) being about
$200
in
1996.

Would that be $200 each, or for all 4?
Incredible, tho, that they've been going for 16 years!! I
wonder
if
city
street light bulbs last that long?



But they're still up, still burning bright, and have just
about
the
same
warm-up time as they did when new.

I have four of these explosion-proof 400W 208V fixtures in my
barn.
They
light up the whole 8000 sq.ft. very effectively. I can
_almost_
work
on
a car without a drop light.

400 W is heavy duty.... My sodium fixtures are a whole
70W....

And even 70 W compete perty well with the city street lights.

But for indoor work, metal halide would be the better choice.
I
think
the
sodium yellow is great for night-time street/highway
illumination,
but
would
be pretty drab in an indoor work environment.

Not only drab. but potentially a bit dangerous. The
low-pressure
versions used for outdoor lighting are so monochromatic that
they
can
make different colors look like the same color. You actually
lose
the
ability to separate some objects.

I gather the high pressure versions are not as bad?

Supposedly. I forget a lot of this, not having had to recall it
since
I was a magazine staffer, but I think the high-pressure types are
actually mixed vapors and they have a broader spectrum. Or maybe
a
wavy spectrum with various spikes, which is more likely. Emphasis
on
"I think."

For photography, they all suck. Really, really suck. I'd mix in
some
incandescent light and sometimes flash, and people would
photograph
with faces that looked like tutti-frutti ice cream from Mars.
Shadows
under their eyebrows would be blue; cheeks would be orange. It
was
quite a sight.

Mine are high pressure -- quite consistent with the city
lighting,
which
was
my intention.

City lighting, unless things have changed, used to be
low-pressure.
They're a lot more efficient.

You'd think high pressure would be more efficient than low
pressure.
If the city lites are low pressure, my high pressure stuff still
blends in
well.

Procrastinating a bit over here, I was reading the box of the high
pressure
sodium buhb, *sez there's mercury*!!
Which would explain the broader spectrum.
If both have Hg, then there goes *dat* explanation.... LOL

Aha! No, I think you've hit it. That sounds familiar. Low-pressure,
high-efficiency bulbs are sodium only.

Another sodium tiddy-bitty:

Ahm watchin some Universe sumpn or other -- such shows I believe are
used to
further mind**** us -- and they're talking about adaptive optics on
telescopes, which via pyooters shift many small mirrors using a ref.
star to
get rid of atmospheric "astigmatism" -- a bit of a recent boon to
astronomy.
NOW they generate a reference star using laser-stimulated sodium
atoms,
which I guess are floating around up there somewhere....
Funny they would pick sodium....

Now you're over my head. I don't know why they'd pick sodium, except
maybe that it emits a highly monochromatic light, or at least that it
has a very sharp and strong emission line that's easy to filter from
the others.

Because it's there. Some sodium from sea salt spray is wafted up into
the upper atmosphere, and can be provoked into glowing by a laser beam.

http://en.wikipedia.org/wiki/Laser_guide_star

Well, strictly speaking, sea-salt is IONIC sodium with different lines
than
atomic sodium.
There are also calcium, potassium, magnesium salts.
But no matter, whatever works....
Overall perty fascinating, tho.

You'd figger that scientists smart enough to figger all this out (I
imagine
this adaptive optics stuff is no easy slam dunk) would be smart enough to
measure the temperature of the earth, eh?? LOL

The hard part is measuring it to tenths of a degree before the invention
of thermometers and temperature standards, so we can distinguish noise
from warming (or cooling) trend.

And, apparently, having the sense not to place sed thermometers over square
miles of black asphalt... LOL

....or heat exchangers.