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Main
Date: 21 Aug 2006 16:43:25
From: jdg
Subject: orion solar filter
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need some thoughts on the 8 inch solar filter from orion . thanks doug
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Date: 21 Aug 2006 12:50:29
From: Merp
Subject: Re: orion solar filter
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If you want to save about $100, you can order a sheet of Baader Solar
Film and build your own. I purchased my sheet from:
http://www.agenaastro.com/
There are many ideas on the web on how to build your own cell and the
web page above also sells pre-made filters. I have never compared the
Baader film to other solar filters, but there are claims that this
material is optically better than glass type filters.
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Date: 22 Aug 2006 05:39:48
From: jdg
Subject: Re: orion solar filter
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On 21 Aug 2006 12:50:29 -0700, "Merp" <putler@cox.net > wrote:
>If you want to save about $100, you can order a sheet of Baader Solar
>Film and build your own. I purchased my sheet from:
>
>http://www.agenaastro.com/
>
>There are many ideas on the web on how to build your own cell and the
>web page above also sells pre-made filters. I have never compared the
>Baader film to other solar filters, but there are claims that this
>material is optically better than glass type filters.
i have used the baader film in the past on a 114mm bushnell reflector
and the view was not that bad . so i have a little bit to compare it
too . but i was looking for a discription of the view with it .
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Date: 21 Aug 2006 13:14:08
From: Joe S.
Subject: Re: orion solar filter
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"jdg" <fossildoug@yahoo.com > wrote in message
news:7noje2hj26ombdfvf22vorg1rp86iolcjb@4ax.com...
> need some thoughts on the 8 inch solar filter from orion . thanks doug
>
I had two solar filters from Orion -- 8-inch for my XT-8 and 90mm for my
ETX-90. Scopes, filters, and several eyepieces were lost in Katrina -- I
was VERY pleased with the solar filters -- I viewed the sun with both scopes
several times and never had a problem.
WARNING: BEFORE LOOKING AT THE SUN -- leave the cover on front lens of the
finder scope. If you don't do this, the finder scope will focus the sun on
itself and will burn itself up almost instantly. Also, remember -- PUT THE
SOLAR FILTER ON THE SCOPE BEFORE POINTING THE SCOPE AT THE SUN.
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Date: 21 Aug 2006 10:46:04
From: Brian Tung
Subject: Re: orion solar filter
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Joe S. wrote:
> WARNING: BEFORE LOOKING AT THE SUN -- leave the cover on front lens of the
> finder scope. If you don't do this, the finder scope will focus the sun on
> itself and will burn itself up almost instantly. Also, remember -- PUT THE
> SOLAR FILTER ON THE SCOPE BEFORE POINTING THE SCOPE AT THE SUN.
I think this is a good tactic, but the finder isn't that likely to burn
itself (unless it's poorly constructed) as much as it is to burn a hand
or a face carelessly placed *behind* the finder. (I've had to pull my
hand back with a start when it got hot, so I know this "works.")
Certainly do not use the finder visually to locate the Sun! The finder
may be used to locate the Sun by centering the Sun's image through the
finder (it's being used in projection mode, after all) in the shadow of
the finder's OTA. However, simpler mechanisms, based on the principle
of the gun sight, can be made or bought. I got mine from Tele Vue
because it looks slick. I *think* it's called the Sol Searcher (heh),
but that might have been the name of the Coronado (now Meade) model. A
quick bit of Googling should turn this up.
--
Brian Tung <brian@isi.edu >
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html
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Date: 21 Aug 2006 15:45:44
From: William Hamblen
Subject: Re: orion solar filter
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On Mon, 21 Aug 2006 10:46:04 -0700 (PDT), brian@isi.edu (Brian Tung)
wrote:
>I think this is a good tactic, but the finder isn't that likely to burn
>itself (unless it's poorly constructed) as much as it is to burn a hand
>or a face carelessly placed *behind* the finder. (I've had to pull my
>hand back with a start when it got hot, so I know this "works.")
You can fry the reticle in the finder easily enough.
--
The night is just the shadow of the Earth.
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Date: 21 Aug 2006 13:49:55
From: Brian Tung
Subject: Re: orion solar filter
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William Hamblen wrote:
> You can fry the reticle in the finder easily enough.
True enough. Maybe it's a good thing those things are internally
stopped. :)
--
Brian Tung <brian@isi.edu >
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html
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Date: 22 Aug 2006 10:01:19
From: Matthew Ota
Subject: Re: orion solar filter
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Sky & Tel reviewed the Baader material a few years ago and rated it
best over all other filters in that wavelength (visual). It is also the
cheapest, but you have to make your own filter cell.
I made one for my 10 inch SCT and also made one for the finder scope.
It works jsut fine.
With good seeing, very fine detail of the photosphere is visible.
It is great for photography too:
http://www.ocastronomers.org/astroimages/album.asp?pic=Sunspot%20486.jpg&cat=Solar%20System\Solar
Matthew Ota
jdg wrote:
> On 21 Aug 2006 12:50:29 -0700, "Merp" <putler@cox.net> wrote:
>
> >If you want to save about $100, you can order a sheet of Baader Solar
> >Film and build your own. I purchased my sheet from:
> >
> >http://www.agenaastro.com/
> >
> >There are many ideas on the web on how to build your own cell and the
> >web page above also sells pre-made filters. I have never compared the
> >Baader film to other solar filters, but there are claims that this
> >material is optically better than glass type filters.
> i have used the baader film in the past on a 114mm bushnell reflector
> and the view was not that bad . so i have a little bit to compare it
> too . but i was looking for a discription of the view with it .
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Date: 22 Aug 2006 10:00:43
From: Matthew Ota
Subject: Re: orion solar filter
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Sky & Tel reviewed the Baader material a few years ago and rated it
best over all other filters in that wavbelenght (visual). It is also
the chepaest, but you ahve to make your own filter cell.
I made one for my 10 inch SCT and also made one for the finder scope.
It works jsut fine.
With good seeing, very fine detail of the photosphere is visible.
It is great for photography too:
http://www.ocastronomers.org/astroimages/album.asp?pic=Sunspot%20486.jpg&cat=Solar%20System\Solar
Matthew Ota
jdg wrote:
> On 21 Aug 2006 12:50:29 -0700, "Merp" <putler@cox.net> wrote:
>
> >If you want to save about $100, you can order a sheet of Baader Solar
> >Film and build your own. I purchased my sheet from:
> >
> >http://www.agenaastro.com/
> >
> >There are many ideas on the web on how to build your own cell and the
> >web page above also sells pre-made filters. I have never compared the
> >Baader film to other solar filters, but there are claims that this
> >material is optically better than glass type filters.
> i have used the baader film in the past on a 114mm bushnell reflector
> and the view was not that bad . so i have a little bit to compare it
> too . but i was looking for a discription of the view with it .
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Date: 22 Aug 2006 12:41:51
From: John Banister
Subject: Forecasting Dark Skies
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What tools do we have available to forecast sky darkness? By darkness, I
mean how inky black a the sky at a particular viewing site will be well
after dark with no moon.
Let me explain. I have observed from my rural location three times in the
past 10 days. During those periods there has been zero cloud cover and no
change in the visible levels of light pollution on the horizon. Observing
periods were the same: from 22:00L to 01:00L.
The first period I could easily see 5 stars in the bowl of the Little Dipper
and the dust lanes in the Milky Way extended all the way to Cygnus. I could
also see the full extension of the Milky Way into Ophiuchus. M4, M7 & M8
were easily seen with the naked eye. They sky was not inky black but it was
a very dark gray and there was very good contrast. The moon was 2 hours away
from rising. Transparency was forecast at 4 out of 5.
The second period the sky was a medium gray. The Milky Way was washed out,
although I could see the extension into Ophiuchus. It looked like the sky
does with a rising quarter moon. M4 and M8 were invisible to the naked eye,
although M7 could just be made out. I could make out 4 stars in the Little
Dipper. Transparency was forecast at 3 out of 5.
The third period was the worst. The sky was a light gray. The Milky Way was
barely visible with no extension into Ophiuchus and no dust lane into
Cygnus. M7 was not visible to the naked eye. I could make out 3 stars in the
Little Dipper. Forecast transparency was 3 of 5. It almost looked like the
full moon was up.
In all these cases there was no cloud cover and transparency was similar. I
do have some medium light pollution from Dallas (80 miles) in my
southwestern sky, so I am assuming that this is the culprit and that
different levels of air clarity have "reflected" the pollution throughout my
skies on the bad viewing days.
When choosing a night to view (or in choosing what objects to view on a
particular night) it would be nice to be able to forecast how dark my skies
will be. Any ideas? Thanks.
-John
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Date: 22 Aug 2006 22:00:25
From: Chris L Peterson
Subject: Re: Forecasting Dark Skies
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On Tue, 22 Aug 2006 12:41:51 -0500, "John Banister" <banister@9plus.net >
wrote:
>In all these cases there was no cloud cover and transparency was similar...
I'd say that the distinguishing difference in these cases was the
transparency- it wasn't similar at all. Transparency for the most part
is a measure of how dark the sky is. The difference between the nights
was probably the result of different particulate amounts (or of
different amounts of water vapor). Try viewing a current water vapor map
like this http://weather.unisys.com/satellite/sat_wv_us.gif and see if
there is a correlation between your sky quality and moisture.
As already noted, the Clear Sky Clocks provide generally accurate
transparency forecasts for most areas.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 23 Aug 2006 10:17:22
From: John Banister
Subject: Re: Forecasting Dark Skies
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Chris, thanks. I was unable to find any historical data on this page, but I
will cross reference it with my Clear Sky Clock to see if it is more useful.
You may have noticed my longer reply on this subject to the group.
-John
"Chris L Peterson" <clp@alumni.caltech.edu > wrote in message
news:9bvme2tc813titn0qvbt8t3e8l9e8a939c@4ax.com...
> On Tue, 22 Aug 2006 12:41:51 -0500, "John Banister" <banister@9plus.net>
> wrote:
>
>>In all these cases there was no cloud cover and transparency was
>>similar...
>
> I'd say that the distinguishing difference in these cases was the
> transparency- it wasn't similar at all. Transparency for the most part
> is a measure of how dark the sky is. The difference between the nights
> was probably the result of different particulate amounts (or of
> different amounts of water vapor). Try viewing a current water vapor map
> like this http://weather.unisys.com/satellite/sat_wv_us.gif and see if
> there is a correlation between your sky quality and moisture.
>
> As already noted, the Clear Sky Clocks provide generally accurate
> transparency forecasts for most areas.
>
> _________________________________________________
>
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
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Date: 22 Aug 2006 15:57:00
From: Steve Holzworth
Subject: Re: Forecasting Dark Skies
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[[ This message was both posted and mailed: see
the "To," "Cc," and "Newsgroups" headers for details. ]]
In article <ecffl701lfe@enews2.newsguy.com >, John Banister
<banister@9plus.net > wrote:
> What tools do we have available to forecast sky darkness? By darkness, I
> mean how inky black a the sky at a particular viewing site will be well
> after dark with no moon.
You want the Clear Sky Clock page http://cleardarksky.com/csk/
It gives local transparency, seeing, darkness, and cloud cover
forecasts based on a weather model run by the Canadian Meterological
Centre.
--
Steve Holzworth "Do not attribute to poor spelling
sch@_nojunk_sas.com That which is actually poor typing..."
Senior Systems Developer - me
SAS Institute - Open Systems R&D UNIX/VMS/MAC
Cary, N.C.
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Date: 23 Aug 2006 10:11:40
From: John Banister
Subject: Re: Forecasting Dark Skies
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Thanks for the replies. I am familiar with the Clear Sky Clock, which
reports on a site about 15 miles from mine. I find CSC to be very useful,
and I used it to report the forecast the transparencies given in my original
message. However, I do not find CSC sufficiently reliable for the question
at hand (how to predict whether a certain sky will be dark or light) for the
following reasons:
1. Darkness. Some have referred to CSC's "Darkness" sky condition. At first
glance that would seem to be what is needed, but further reading shows that
it is basically a report on when the sun and moon are up with some
atmospheric scattering (the link for this is broken) factor thrown in. It
seems to be unreliable for the purpose at hand. When the moon is down (or
new) it always reports black even when the transparency line reports poor
transparency. As an example, tonight's forecast is 6.0 (the highest) for
darkness and Below Average for transparency.
2. Transparency. I had originally though this would be a good predictor but
after looking at this for a few months I wonder. I observed dark nights with
average transparency (as forecast by CSC) and not so dark with above average
transparency. My guess is that this is because CSC's transparency reporting
is for water vapor only. It is my understanding that transparency can be
effected by other criteria, such as dust and other airborne particulates,
which would be missed by CSC. Out here in Texas we have lot's of
particulates. <G >
So, if transparency is dependent on more than water vapor is there a source
which predicts "true" (or total) transparency, including water vapor and
other stuff? Maybe infrared satellite photography?
Thanks again.
-John
"Steve Holzworth" <sch@_nojunk_sas.com > wrote in message
news:220820061557004091%sch@_nojunk_sas.com...
> [[ This message was both posted and mailed: see
> the "To," "Cc," and "Newsgroups" headers for details. ]]
>
> In article <ecffl701lfe@enews2.newsguy.com>, John Banister
> <banister@9plus.net> wrote:
>
>> What tools do we have available to forecast sky darkness? By darkness, I
>> mean how inky black a the sky at a particular viewing site will be well
>> after dark with no moon.
>
> You want the Clear Sky Clock page http://cleardarksky.com/csk/
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Date: 23 Aug 2006 17:39:16
From: AstroApp
Subject: Re: orion solar filter
|
On Mon, 21 Aug 2006 16:43:25 GMT, jdg <fossildoug@yahoo.com > wrote:
>need some thoughts on the 8 inch solar filter from orion . thanks doug
Nobody seems to have answered your question and though I don't have
the EIGHT inch model, I do have the five inch filter, which I bought
for my Orion StarBlaster and Sky View Pro 127 refractor.
I am entirely happy with the filter. It is almost perfectly made;
examining the glass via a very bright light I see absolutely no pin
holes. Nor do I see any if I hold it up against the sun (carefully!)
It is very well manufactured, using a sturdy aluminum frame that seems
made to high standards. It looks like it's worth the money, just
examined as a product in terms of its finish and quality.
The sharpness of the view is excellent and there is no change of color
cast. I really do not like looking at a blue sun, so in this respect
it is better than some of the mylar filter sheets I've tried.
I took a picture of a large sunspot region, which is currently at the
bottom of my homepage (though I change the picture there fairly
often):
http://home.earthlink.net/~steve_waldee/index.html
If, by the time you go to the page, it is not there, I also have
another version of it in this article:
http://home.earthlink.net/~steve_waldee/digital/webcam-solar.htm
-- which does not have as much processing.
I must say that these pictures are rather poor compared to the live
eye view, due to the lack of resolution of my modified Logitech
webcam.
Now, as to the aperture of solar filters:
You will virtually never achieve the full aperture resolution of an 8
inch telescope looking at the sun during the day. Under near ideal
conditions such a scope could split a 0.6 arcsecond equal magnitude
double star in a flawless, steady night-time sky. But, in the
turbulent, heated air of the day, you'd be lucky to get angular
resolution of a few arcseconds at best. Thus, your 8 inch scope
probably won't give much more resolution than a 2 inch aperture, or
even less (this is one reason that the small Coronado personal solar
telescope can work so well: it really does not need more than 40-90 mm
aperture to be able to resolve fine solar details.)
Therefore, an off-axis 60-70mm solar filter will PROBABLY give you
close to the resolution performance on your 8 inch scope that a full
aperture 8 inch solar filter will. You will note that the Orion solar
filter for their 12 inch Dob is actually a 4 inch filter mounted on a
metal plate.
The price for the Orion filters for 8 inch scopes is really quite
affordable, being less than twice what I paid for mine (a 4.57" clear
aperture model.) At this price, why not go full-aperture?
The one I bought came with some extra gummed shims in case the fit was
loose. I put them inside the rubber lined aluminum frame so that the
fit was a bit tighter around the dew shield of my 127mm refractor. In
moving the scope around normally, the filter shows no sign of a
tendency to fall off or to loosen.
I have owned three different solar filters and of the neutral-density
ones I've had, purchased more than 20 years ago, the Orion unit seems
to me to yield better views. I am entirely satisfied with this
product (though I must say that this is not always true of the
company's eyepieces, which sometimes lack adequate internal baffling.)
I might suggest that you make up a better case for the filter, as it
benefits from one that is more sturdy than the cardboard box that is
comes in. I used a tin box for expensive candies, adding internal
padding (photo shown in the article previously mentioned, above.) The
side benefit of this is that you get to eat the candies!
AstroApp
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Date: 24 Aug 2006 04:20:00
From: jdg
Subject: Re: orion solar filter
|
On Wed, 23 Aug 2006 17:39:16 GMT, AstroApp <AstroApp@blocked.net >
wrote:
>On Mon, 21 Aug 2006 16:43:25 GMT, jdg <fossildoug@yahoo.com> wrote:
>
>>need some thoughts on the 8 inch solar filter from orion . thanks doug
>
>Nobody seems to have answered your question and though I don't have
>the EIGHT inch model, I do have the five inch filter, which I bought
>for my Orion StarBlaster and Sky View Pro 127 refractor.
>
>I am entirely happy with the filter. It is almost perfectly made;
>examining the glass via a very bright light I see absolutely no pin
>holes. Nor do I see any if I hold it up against the sun (carefully!)
>It is very well manufactured, using a sturdy aluminum frame that seems
>made to high standards. It looks like it's worth the money, just
>examined as a product in terms of its finish and quality.
>
>The sharpness of the view is excellent and there is no change of color
>cast. I really do not like looking at a blue sun, so in this respect
>it is better than some of the mylar filter sheets I've tried.
>
>I took a picture of a large sunspot region, which is currently at the
>bottom of my homepage (though I change the picture there fairly
>often):
>http://home.earthlink.net/~steve_waldee/index.html
>
>If, by the time you go to the page, it is not there, I also have
>another version of it in this article:
>http://home.earthlink.net/~steve_waldee/digital/webcam-solar.htm
>-- which does not have as much processing.
>
>I must say that these pictures are rather poor compared to the live
>eye view, due to the lack of resolution of my modified Logitech
>webcam.
>
>Now, as to the aperture of solar filters:
>
>You will virtually never achieve the full aperture resolution of an 8
>inch telescope looking at the sun during the day. Under near ideal
>conditions such a scope could split a 0.6 arcsecond equal magnitude
>double star in a flawless, steady night-time sky. But, in the
>turbulent, heated air of the day, you'd be lucky to get angular
>resolution of a few arcseconds at best. Thus, your 8 inch scope
>probably won't give much more resolution than a 2 inch aperture, or
>even less (this is one reason that the small Coronado personal solar
>telescope can work so well: it really does not need more than 40-90 mm
>aperture to be able to resolve fine solar details.)
>
>Therefore, an off-axis 60-70mm solar filter will PROBABLY give you
>close to the resolution performance on your 8 inch scope that a full
>aperture 8 inch solar filter will. You will note that the Orion solar
>filter for their 12 inch Dob is actually a 4 inch filter mounted on a
>metal plate.
>
>The price for the Orion filters for 8 inch scopes is really quite
>affordable, being less than twice what I paid for mine (a 4.57" clear
>aperture model.) At this price, why not go full-aperture?
>
>The one I bought came with some extra gummed shims in case the fit was
>loose. I put them inside the rubber lined aluminum frame so that the
>fit was a bit tighter around the dew shield of my 127mm refractor. In
>moving the scope around normally, the filter shows no sign of a
>tendency to fall off or to loosen.
>
>I have owned three different solar filters and of the neutral-density
>ones I've had, purchased more than 20 years ago, the Orion unit seems
>to me to yield better views. I am entirely satisfied with this
>product (though I must say that this is not always true of the
>company's eyepieces, which sometimes lack adequate internal baffling.)
>
>I might suggest that you make up a better case for the filter, as it
>benefits from one that is more sturdy than the cardboard box that is
>comes in. I used a tin box for expensive candies, adding internal
>padding (photo shown in the article previously mentioned, above.) The
>side benefit of this is that you get to eat the candies!
>
>AstroApp
that is what i have been looking for . it seems that i have made a
good choice in buying from orion . the solar filter will be getting
alot of use on tehe weekends and at the star partys . thanks for the
very usefull info . thanks doug
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