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[OL-Forum] Digest Number 552
OutdoorLighting-Forum "The largest uncensored and most active non-geographic based forum on light pollution."
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There are 6 messages in this issue.
Topics in this digest:
1. Re: LightFromAbove Down
From: "John M. McMahon" <mcmahon@mail....edu>
2. Re: Human Beings Actually Can See in The Dark (Part I)
From: John Gilkison <jgilkiso@zianet...>
3. Re: 3-watt CFs
From: Steve Davis <w2sgd@juno...>
4. Dangerous forward throw
From: Steve Davis <w2sgd@juno...>
5. Semi-TAN: binocular advice sought
From: "John M. McMahon" <mcmahon@mail....edu>
6. Re: LightFromAbove Down
From: Scott Griswold <griz@lightfromabove...>
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Message: 1
Date: Fri, 02 Aug 2002 07:43:38 -0400
From: "John M. McMahon" <mcmahon@mail....edu>
Subject: Re: LightFromAbove Down
scottgriz wrote:
> In other news, the debate heats up at
> http://www.theamericanmind.com
>
> The owner of the site even went as far as mentioning OLF on his
> web site. I guess he must monitor this forum. I hope he
> manages to pick up some good information here and learns
> from it. He doesn't seem too informed on the intent of LP reform.
> He seems to think we are only about preserving the night sky
> and he doesn't say much about why preventing glare and
> stopping wasted energy is a good idea.
Here's what I wrote just now. I'm ready for the inevitable
attacks ...
"The loss of the night sky is more than just an issue of
light pollution ... or better *sight* pollution; it
represents a loss of our culture and self-knowledge as well.
When the night sky, with all of its inspiration and beauty,
becomes more and more simply another extension of a strip
mall world cluttered by the wasteful debris of human
activity, we lose the sense of perspective humans have had
since they first were able to look upward. To look out into
the sky and realize that there exists a reality beyond our
own and to be able to reflect on that reality is something
exclusively human. We now risk that part of our humanity
when we use excessive and wasteful illumination.
The ancients knew the importance of our ablility to look
beyond our own world. Plato considered the sight of the
cosmos to be the origin of all science and philosophy.
Cicero wrote that even if people lived their entire lives
underground in comfort and surrounded by material wealth,
when they first saw they starry sky, they would surely
recognize the existence of the spiritual powers beyond themselves.
Without the ability to comprehend the sky because of an
unnecessary and excessive luminous fog that nightly
surrounds most us, we limit ourselves to a limited and
self-centered view of the real, non-human world around us.
And that separates us from a larger reality.
This need not be, and we should strive to correct this
easily-solved problem by using the kinds of sensible and
efficient outdoor lighting that will ensure that our
present culture will be able to see beyond itself."
John McMahon
Classics
Le Moyne College
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Message: 2
Date: (unknown)
From: John Gilkison <jgilkiso@zianet...>
Subject: Re: Human Beings Actually Can See in The Dark (Part I)
HUMANS BEINGS ACTUALLY CAN SEE IN THE DARK! 2002
Collectively as a society we are using lighting outdoors at night in some
very unproductive ways
which are costing us a lot of money. Current estimates run from 1.5 billion
to 2 billion dollars
annually for wasted electricity from unshielded lighting, over lighting, and
other poor lighting
practices. Not only that, but light pollution is depriving us of a wonderful
birthright, that is a
vision of star filled night sky. Any amateur astronomer worth his salt knows
and takes for
granted something much of the population is seemingly unaware of, that is,
"human beings
actually can see in the dark". To observe the night sky and use a telescope
you must learn to
allow your eye to adapt to the dark, and only use a low powered red light to
read maps, and to
avoid the use of white light as much as possible.
There are three different levels of light adaption for the eye that need
to understood. The first
which we all are most aware of is daylight adaption at high light levels.
This is called Photopic
Vision. Here the eye's spectral sensitivity is centered around yellow/green
wavelengths of light,
matching the Suns peak output. In the retina the eye our color receptors
(Cones), are employed
in bright light where we have our best visual acuity with color vision.
The second level is a transition state from Photopic Vision to dark
adaption and it is known as
Mesopic Vision. Under lower light condition the eye uses both the daylight
vision receptors
(cones) and some dark adaption receptors (rods) which are more light
sensitive, but only see in
shades of gray. One of the best examples of this is driving in the country
at night where you can
look out the window and see the stars, even though your headlights appear to
brightly illuminate
the road. The amount of white light being reflected back to you from the
road is really very low
but our headlights appear bright because our eyes are dark adapted. In many
places under city
street lights you often can't tell if your headlights are even on without
your dash lights!
Finally there is dark adaption or Scotopic Vision, which is a process that
takes time. Entering a
dark area the first thing the eye does is dilate the pupils. In an adult
this can be as much as 7 or 8
mm's. Then a chemical change takes place in the eye called visual purple
which gives the rods
their sensitivity to light centered 48 nm higher then daylight vision
(toward the blue). The human
eye is biologically designed to see by starlight at night. It takes about
several minutes to get to
where you can see well in the dark. The dark adaption process can continue
for up to 30 minutes
increasing light sensitivity even more. Exposure to a bright white light can
bleach this visual
purple out of the eye and set the whole dark adaption process back almost to
the beginning.
All the light of the stars collectively is equivalent to the light output
of a 60 watt lightbulb as
seen from 100 yards away. Of course the stars are spread out over the whole
sky so there is no
glare. You will notice that at a dark site the ground appears to glow after
about 15 minutes. We
can see well in the dark, we just can't see in color, or see with good
acuity. We can see general
shapes. Interestingly enough the eye is even more light sensitive off axis (
because more rods
are locate on the retina off axis) so that movement off axis is detected
sooner then things directly
in front of you. Amateur astronomers use this in a observing method called
averted vision where
even fainter deep sky objects can be see, then can be seen when looked at
directly.
With our over lit outdoor landscapes the average citizen seldom gets
acquainted with their dark
adaption capabilities anymore. This is what I call the triple whammy of
light pollution. First the
sheer numbers of unshielded and excessively bright lights fill the lower
atmosphere with back
scattered light. This is like turning up the contrast on your television so
you can hardly see the
picture anymore. Instead of a sky with up to 2,500 stars in it (up to 6th
magnitude stars) we often
have in our city skies not more the a couple dozen stars up to the 3rd
magnitude. The second part
of the problem is that also there is seldom anywhere to go to escape
lighting so our eyes can not
become dark adapted. If you become blessed with a local power outage that
shuts down nearby
streetlights you usually can see a magnitude deeper, seeing a couple hundred
stars versus only a
couple dozen. Finally because lights are often unshielded, you see the
lights directly even though
they may be at such a distance they no longer providing useful illumination.
The glare from these
distant lights however are still reducing dark adaption.
Strangely enough with no clouds the sky can still appear dark in the city,
just much more starless.
I call this the "Dark Sky Illusion". The eye adapts to the brightest light
levels in a given scene and
we seem to have a night time dark sky appearance hard wired into us. You can
then drive out of
the city, dark adapt, and observe a sky with thousands of stars, but the
sky itself will appear no
darker. Stranger still you can look back at the bright dome over the city
you were just in and it
then appears bright in comparison. I can't say this enough, "the human eye
can adapt to a very
wide range of light levels.
Part II on Monday
*
John Gilkison
President, National
Public Observatory
jgilkiso@zianet...
www.astronomy-national-
public-observatory.org
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Message: 3
Date: Fri, 2 Aug 2002 10:11:03 -0400
From: Steve Davis <w2sgd@juno...>
Subject: Re: 3-watt CFs
Karolyn Beebe wrote:
<I wondered about the 3 watt bulbs in carriage style
lights that Steve wrote about while back, in an area
sans streetlights. Well my daughter sent me a 3 watt
compact florescent that she picked up at a Home
Depot in CT. It's base is for a small socket.>
Correction. My astro friend is using 3-watt incandescent
bulbs (small base?). They produce much less light and
much less LP. His neighbors are even catching on.
They look good -- like small candles. [It's all about
"sex appeal" anyway and for that you have to advertise
and attract attention.]
My yard is no light (except for the *@#$! streetlight).
Another option people may want to consider is the 15-watt
incandescent bulb with a medium base (standard sized socket
for most household lamps). For unshielded fixtures it is
less glary than 25, 40, 60, and 100 watt bulbs and perfectly
adequate in the terms of lighting the area. -sd
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Message: 4
Date: Fri, 2 Aug 2002 10:28:16 -0400
From: Steve Davis <w2sgd@juno...>
Subject: Dangerous forward throw
I had an experience last night when I pulled into a new
Hess station to check out a nearby motel sign. Hess uses
LSI as its corporate lighting designer, and they use LSI
manufactured lights. This place is bright - designed for
65 fc maintained at the pump! 400W MH FCO canopy lights
and 1000 MH FCO forward throw around the perimeter. That
forward throw totally ruined my vision at the exit. I could
not see the traffic coming done the road on the side were
the light was. It was worse than a flash bulb going off
and burned a hole in the retina of at least one eye that
lasted a short distance after leaving the gas station. This is
another example of a designer who only sits in the office in
some distant city and never checks his work out in he field.
The numbers look good to him on paper, but he hasn't got
a clue as to what he is doing even though the note in the
margin of engineering drawing says IESNA methods were used. -sd
________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today! For your FREE software, visit:
http://dl.www.juno.com/get/web/.
________________________________________________________________________
________________________________________________________________________
Message: 5
Date: Fri, 02 Aug 2002 19:27:53 -0400
From: "John M. McMahon" <mcmahon@mail....edu>
Subject: Semi-TAN: binocular advice sought
Dear NPO/OLFers:
Orion has just cut its prices on its line of Little Giant II
Binoculars by $40 for the 11x79, 15x70 or 20x70 models:
---
"Little Giant II Binoculars, powerful, light-grabbing 70mm
binos that rock for astronomy. Save $40 on any of the three models:
http://www.telescope.com/cgi-bin/OrionTel.storefront/EN/product/Product.View.C021
11x70 Little Giant II, Was $269, NOW $229
15x70 Little Giant II, Was $279, NOW $239
20x70 Little Giant II, Was $289, NOW $249"
---
Since I have been doing a good deal of serious observing
with my old Tasco 7x50s and with excellent WW2 vintage
Bausch and Lomb 6x30s (thanks to my father-in-law), I've
been looking to move up a bit. Is now the time to take advantage?
Any experience with and/or opinions on a) the general
quality of Orion LGIIs, b) the size considerations, and c)
the use of the tripod L-adapter would be appreciated.
I've read the Sept. S&T's piece on binoculars, btw, but I'd
like some first-hand info if possible. My experience with
Orion's XT8 (the earlier model from 1999) has been very good
and quite productive for the most part over the last 2.5 years.
Thanx.
Darker skies,
John McMahon
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Message: 6
Date: Sat, 3 Aug 2002 00:07:17 -0400
From: Scott Griswold <griz@lightfromabove...>
Subject: Re: LightFromAbove Down
Great reply John. My site is back up. Thought for a while it had been
hacked. Just troubles with the server from my provider.
-Scott
On Friday, August 2, 2002, at 07:43 AM, John M. McMahon wrote:
> scottgriz wrote:
>
> > In other news, the debate heats up at
> > http://www.theamericanmind.com
> >
> > The owner of the site even went as far as mentioning OLF on his
> > web site. I guess he must monitor this forum. I hope he
> > manages to pick up some good information here and learns
> > from it. He doesn't seem too informed on the intent of LP reform.
> > He seems to think we are only about preserving the night sky
> > and he doesn't say much about why preventing glare and
> > stopping wasted energy is a good idea.
>
> Here's what I wrote just now. I'm ready for the inevitable
> attacks ...
>
> "The loss of the night sky is more than just an issue of
> light pollution ... or better *sight* pollution; it
> represents a loss of our culture and self-knowledge as well.
>
> When the night sky, with all of its inspiration and beauty,
> becomes more and more simply another extension of a strip
> mall world cluttered by the wasteful debris of human
> activity, we lose the sense of perspective humans have had
> since they first were able to look upward. To look out into
> the sky and realize that there exists a reality beyond our
> own and to be able to reflect on that reality is something
> exclusively human. We now risk that part of our humanity
> when we use excessive and wasteful illumination.
>
> The ancients knew the importance of our ablility to look
> beyond our own world. Plato considered the sight of the
> cosmos to be the origin of all science and philosophy.
> Cicero wrote that even if people lived their entire lives
> underground in comfort and surrounded by material wealth,
> when they first saw they starry sky, they would surely
> recognize the existence of the spiritual powers beyond themselves.
>
> Without the ability to comprehend the sky because of an
> unnecessary and excessive luminous fog that nightly
> surrounds most us, we limit ourselves to a limited and
> self-centered view of the real, non-human world around us.
> And that separates us from a larger reality.
>
> This need not be, and we should strive to correct this
> easily-solved problem by using the kinds of sensible and
> efficient outdoor lighting that will ensure that our
> present culture will be able to see beyond itself."
>
> John McMahon
> Classics
> Le Moyne College
>
>
>
> OutdoorLighting-Forum "The largest uncensored and most active
> non-geographic based forum on light pollution."
> To unsubscribe from a Yahoo list send a blank email to
> listname-unsubscribe@yahoogroups...
>
> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
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