RE: [Utah-astronomy] Re: Star party etiquette forcrumbcrunchersandparents
That is another reason I don't like to leave my scope up during the daytime, besides animals getting to it. A big dobsonian could cause a forest fire or blind someone. Debbie
[Original Message] From: Patrick Wiggins <paw@trilobyte.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Date: 9/28/2004 11:10:18 AM Subject: [Utah-astronomy] Re: Star party etiquette forcrumbcrunchersandparents
I seem to remember many years back a star party up by Kamas where Brent's monster scope ended up catching a frisbee or two. But then I seem to also remember that later in the day the scope became a chimney when sunlight found its way to the primary mirror and smoke was seen emanating from the tube...
Patrick
Chuck Hards wrote:
Don't be so sure; I've seen many telescopes (present company excepted, of course) that may as well have been trash-cans...
--- John and Lisa Zeigler <john@johnstelescopes.com> >
Solid tube Newtonian telescopes, no matter how much they look like
trash cans or basket ball hoops are not for throwing things into..
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Debbie, I have no memory of anything which might have happened at Bald Mountain (not Kamas). If I did, I would deny it. But if anything DID happen, it was purely intentional. (I only caught the Frisbee twice, and I never did see the sun's projected image.) Acutally, the amount of heat per unit area generated is proportional to the inverse of the f ratio squared of the scope, not the aperture. My 22" is an f6.3. An f4.5 would put more heat in a smaller spot. Brent --- Debbie <astrodeb@earthlink.net> wrote:
That is another reason I don't like to leave my scope up during the daytime, besides animals getting to it. A big dobsonian could cause a forest fire or blind someone.
Debbie
[Original Message] From: Patrick Wiggins <paw@trilobyte.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Date: 9/28/2004 11:10:18 AM Subject: [Utah-astronomy] Re: Star party etiquette forcrumbcrunchersandparents
I seem to remember many years back a star party up by Kamas where Brent's monster scope ended up catching a frisbee or two. But then I seem to also remember that later in the day the scope became a chimney when sunlight found its way to the primary mirror and smoke was seen emanating from the tube...
Patrick
Chuck Hards wrote:
Don't be so sure; I've seen many telescopes
(present
company excepted, of course) that may as well have been trash-cans...
--- John and Lisa Zeigler <john@johnstelescopes.com> >
Solid tube Newtonian telescopes, no matter how much they look like
trash cans or basket ball hoops are not for throwing things into..
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We have a 1/4" plywood shield over our mirror on the truss tube Dob. It sits about an inch over the mirror on three screws from the mirror cell. This protects it from wind, rain, dust, and the forest from harm. Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com -----Original Message----- From: Debbie [mailto:astrodeb@earthlink.net] Sent: Tuesday, September 28, 2004 1:17 PM To: Utah Astronomy; Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star party etiquetteforcrumbcrunchersandparents That is another reason I don't like to leave my scope up during the daytime, besides animals getting to it. A big dobsonian could cause a forest fire or blind someone. Debbie
[Original Message] From: Patrick Wiggins <paw@trilobyte.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Date: 9/28/2004 11:10:18 AM Subject: [Utah-astronomy] Re: Star party etiquette forcrumbcrunchersandparents
I seem to remember many years back a star party up by Kamas where Brent's monster scope ended up catching a frisbee or two. But then I seem to also remember that later in the day the scope became a chimney
when sunlight found its way to the primary mirror and smoke was seen emanating from the tube...
Patrick
Chuck Hards wrote:
Don't be so sure; I've seen many telescopes (present company excepted, of course) that may as well have been trash-cans...
--- John and Lisa Zeigler <john@johnstelescopes.com> >
Solid tube Newtonian telescopes, no matter how much they look like
trash cans or basket ball hoops are not for throwing things into..
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The forest is no more at risk from a alrge scope than from a small scope. It is pretty hard to get enough energy out of a scope and across a distance large enough to do any damage. The image, and the energy in the image, spread out very quickly and become a non-problem. Brent --- John and Lisa Zeigler <john@johnstelescopes.com> wrote:
We have a 1/4" plywood shield over our mirror on the truss tube Dob. It sits about an inch over the mirror on three screws from the mirror cell. This protects it from wind, rain, dust, and the forest from harm.
Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com
-----Original Message----- From: Debbie [mailto:astrodeb@earthlink.net] Sent: Tuesday, September 28, 2004 1:17 PM To: Utah Astronomy; Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star party etiquetteforcrumbcrunchersandparents
That is another reason I don't like to leave my scope up during the daytime, besides animals getting to it. A big dobsonian could cause a forest fire or blind someone.
Debbie
[Original Message] From: Patrick Wiggins <paw@trilobyte.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Date: 9/28/2004 11:10:18 AM Subject: [Utah-astronomy] Re: Star party etiquette forcrumbcrunchersandparents
I seem to remember many years back a star party up by Kamas where Brent's monster scope ended up catching a frisbee or two. But then I seem to also remember that later in the day the scope became a chimney
when sunlight found its way to the primary mirror and smoke was seen emanating from the tube...
Patrick
Chuck Hards wrote:
Don't be so sure; I've seen many telescopes
(present company
excepted, of course) that may as well have been trash-cans...
--- John and Lisa Zeigler <john@johnstelescopes.com> >
Solid tube Newtonian telescopes, no matter how much they look like
trash cans or basket ball hoops are not for throwing things into..
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Ya, John did the physics of it for me last night and figured out exactly what diameter mirror at what focal length you would need to start a fire. Let me tell you, it aint going to happen! Sometimes its difficult living with an over analyzer. I just meant it figuratively. Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com -----Original Message----- From: Brent Watson [mailto:brentjwatson@yahoo.com] Sent: Wednesday, September 29, 2004 7:52 AM To: Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star partyetiquetteforcrumbcrunchersandparents The forest is no more at risk from a alrge scope than from a small scope. It is pretty hard to get enough energy out of a scope and across a distance large enough to do any damage. The image, and the energy in the image, spread out very quickly and become a non-problem. Brent --- John and Lisa Zeigler <john@johnstelescopes.com> wrote:
We have a 1/4" plywood shield over our mirror on the truss tube Dob. It sits about an inch over the mirror on three screws from the mirror cell. This protects it from wind, rain, dust, and the forest from harm.
Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com
-----Original Message----- From: Debbie [mailto:astrodeb@earthlink.net] Sent: Tuesday, September 28, 2004 1:17 PM To: Utah Astronomy; Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star party etiquetteforcrumbcrunchersandparents
That is another reason I don't like to leave my scope up during the daytime, besides animals getting to it. A big dobsonian could cause a forest fire or blind someone.
Debbie
[Original Message] From: Patrick Wiggins <paw@trilobyte.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Date: 9/28/2004 11:10:18 AM Subject: [Utah-astronomy] Re: Star party etiquette forcrumbcrunchersandparents
I seem to remember many years back a star party up by Kamas where Brent's monster scope ended up catching a frisbee or two. But then I seem to also remember that later in the day the scope became a chimney
when sunlight found its way to the primary mirror and smoke was seen emanating from the tube...
Patrick
Chuck Hards wrote:
Don't be so sure; I've seen many telescopes
(present company
excepted, of course) that may as well have been trash-cans...
--- John and Lisa Zeigler <john@johnstelescopes.com> >
Solid tube Newtonian telescopes, no matter how much they look like
trash cans or basket ball hoops are not for throwing things into..
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Lisa, read my last post. Yes, you CAN start a fire with a telescope mirror, it's just unlikely on-axis unless tinder is very near the focal plane. Eyepieces left on a chart table can do the trick, too, and tell all those folks with melted Telrad reticles that the sun isn't a problem. I would like to see John's calculations, assumptions. I have several large mirrors and am happy to demonstrate the off-axis danger on a sunny day. --- John and Lisa Zeigler <john@johnstelescopes.com> wrote:
Ya, John did the physics of it for me last night and figured out exactly what diameter mirror at what focal length you would need to start a fire. Let me tell you, it aint going to happen! Sometimes its difficult living with an over analyzer. I just meant it figuratively.
Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com
-----Original Message----- From: Brent Watson [mailto:brentjwatson@yahoo.com] Sent: Wednesday, September 29, 2004 7:52 AM To: Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star partyetiquetteforcrumbcrunchersandparents
The forest is no more at risk from a alrge scope than from a small scope. It is pretty hard to get enough energy out of a scope and across a distance large enough to do any damage. The image, and the energy in the image, spread out very quickly and become a non-problem.
Brent
--- John and Lisa Zeigler <john@johnstelescopes.com> wrote:
We have a 1/4" plywood shield over our mirror on the truss tube Dob. It sits about an inch over the mirror on three screws from the mirror cell. This protects it from wind, rain, dust, and the forest from harm.
Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com
-----Original Message----- From: Debbie [mailto:astrodeb@earthlink.net] Sent: Tuesday, September 28, 2004 1:17 PM To: Utah Astronomy; Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star party etiquetteforcrumbcrunchersandparents
That is another reason I don't like to leave my scope up during the daytime, besides animals getting to it. A big dobsonian could cause a forest fire or blind someone.
Debbie
[Original Message] From: Patrick Wiggins <paw@trilobyte.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Date: 9/28/2004 11:10:18 AM Subject: [Utah-astronomy] Re: Star party etiquette forcrumbcrunchersandparents
I seem to remember many years back a star party up by Kamas where Brent's monster scope ended up catching a frisbee or two. But then I seem to also remember that later in the day the scope became a chimney
when sunlight found its way to the primary mirror and smoke was seen emanating from the tube...
Patrick
Chuck Hards wrote:
Don't be so sure; I've seen many telescopes
(present company
excepted, of course) that may as well have been trash-cans...
--- John and Lisa Zeigler <john@johnstelescopes.com> >
Solid tube Newtonian telescopes, no matter how much they look like
trash cans or basket ball hoops are not for throwing things into..
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Chuck, I whole heartedly apologize! You are completely correct. I misunderstood what he was saying and his findings. John's findings led him to the fact that any scope of any aperture, or any focal length, and even uncoated in the right conditions could start a fire, given the right conditions. I completely misunderstood what he was saying an shot off before I should have (typical of this wife not completely listening). I will completely digress on this issue and speak no more except to say, keep all mirrors and lenses covered, put eyepieces in their boxes and don't leave your scope set up during the day if you do not have to. Even a very large or very small scope produces lots of heat given the right conditions. Lisa Zeigler
No worries, Lisa. Actually I must confess a bit of envy. My own dear wife of nearly 19 years has zero interest in astronomy or telescope-making. Had she shared even a tiny portion of my own zeal, I would have much more (read ANY) time to enjoy the hobby. Hard to beleive that it's been over 4 years since my last S&T article, and no new activity is in sight. Sigh. Keep up the good work! --- John and Lisa Zeigler <john@johnstelescopes.com> wrote:
Chuck,
I whole heartedly apologize! You are completely correct. I misunderstood what he was saying and his findings.
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Thanks Chuck. Lisa Zeigler -----Original Message----- From: Chuck Hards [mailto:chuckhards@yahoo.com] Sent: Wednesday, September 29, 2004 11:34 AM To: Utah Astronomy Subject: RE: [Utah-astronomy] Re: Starpartyetiquetteforcrumbcrunchersandparents No worries, Lisa. Actually I must confess a bit of envy. My own dear wife of nearly 19 years has zero interest in astronomy or telescope-making. Had she shared even a tiny portion of my own zeal, I would have much more (read ANY) time to enjoy the hobby. Hard to beleive that it's been over 4 years since my last S&T article, and no new activity is in sight. Sigh. Keep up the good work!
Starting a fire is just as unlikely off axis as well. The light cone doesn't change much off axis, and most folks don't park their scopes within a focal length of tinder. If they did they wouldn't have much of the sky visible. You must also have a fast enog=ugh scope to start the fire. The focal ratio required to do this is much smaller than most scopes. You really have to try to do any damage. The reticle in a Telrad doesn't catch fire, it just melts - a much lower temperature is required to melt mylar than to burn something up. There is a tale that one of the ancients started the sails of his oponents ships on fire by stationing his troups around the bay with individual mirrors, and then having them focus their mirrors on the sails. It has been shown that this too is very improbable. Brent --- Chuck Hards <chuckhards@yahoo.com> wrote:
Lisa, read my last post. Yes, you CAN start a fire with a telescope mirror, it's just unlikely on-axis unless tinder is very near the focal plane.
Eyepieces left on a chart table can do the trick, too, and tell all those folks with melted Telrad reticles that the sun isn't a problem.
I would like to see John's calculations, assumptions.
I have several large mirrors and am happy to demonstrate the off-axis danger on a sunny day.
--- John and Lisa Zeigler <john@johnstelescopes.com> wrote:
Ya, John did the physics of it for me last night and figured out exactly what diameter mirror at what focal length you would need to start a fire. Let me tell you, it aint going to happen! Sometimes its difficult living with an over analyzer. I just meant it figuratively.
Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com
-----Original Message----- From: Brent Watson [mailto:brentjwatson@yahoo.com]
Sent: Wednesday, September 29, 2004 7:52 AM To: Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star partyetiquetteforcrumbcrunchersandparents
The forest is no more at risk from a alrge scope than from a small scope. It is pretty hard to get enough energy out of a scope and across a distance large enough to do any damage. The image, and the energy in the image, spread out very quickly and become a non-problem.
Brent
--- John and Lisa Zeigler <john@johnstelescopes.com> wrote:
We have a 1/4" plywood shield over our mirror on the truss tube Dob. It sits about an inch over the mirror on three screws from the mirror cell. This protects it from wind, rain, dust, and the forest from harm.
Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com
-----Original Message----- From: Debbie [mailto:astrodeb@earthlink.net] Sent: Tuesday, September 28, 2004 1:17 PM To: Utah Astronomy; Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star party etiquetteforcrumbcrunchersandparents
That is another reason I don't like to leave my scope up during the daytime, besides animals getting to it. A big dobsonian could cause a forest fire or blind someone.
Debbie
[Original Message] From: Patrick Wiggins <paw@trilobyte.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Date: 9/28/2004 11:10:18 AM Subject: [Utah-astronomy] Re: Star party etiquette forcrumbcrunchersandparents
I seem to remember many years back a star party up by Kamas where Brent's monster scope ended up catching a frisbee or two. But then I seem to also remember that later in the day the scope became a chimney
when sunlight found its way to the primary mirror and smoke was seen emanating from the tube...
Patrick
Chuck Hards wrote:
Don't be so sure; I've seen many telescopes
(present company
excepted, of course) that may as well have been trash-cans...
--- John and Lisa Zeigler <john@johnstelescopes.com> >
Solid tube Newtonian telescopes, no matter how much they look like > trash cans or basket ball hoops are not for throwing things into..
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Brent, you are a nice guy but a hell of a nit picker. I just lost interest in this thread, pretty much completely. --- Brent Watson <brentjwatson@yahoo.com> wrote:
Starting a fire is just as unlikely off axis as well.
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Brent, a nit picker??? ;) Quoting Chuck Hards <chuckhards@yahoo.com>:
Actually, everyone forgets to subtract their edge bevel. Most folks are surprised to find that their clear aperture is sometimes almost 1/4" less than the stated size. My own, old, old 17.5" mirror has a clear aperture of ~17.35" when the bevel is subtracted. I'd be willing to bet that Daniels isn't a true 17.5" too. Hope that doesn't ruin his day.
Quoting Chuck Hards <chuckhards@yahoo.com>:
Brent, you are a nice guy but a hell of a nit picker.
I just lost interest in this thread, pretty much completely.
--- Brent Watson <brentjwatson@yahoo.com> wrote:
Starting a fire is just as unlikely off axis as well.
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You're the one who brought up "an inch and a half among friends" in the first place! ;) But the point is that sometimes you need a little precision, as with most optical algorithms, and sometimes you don't, as in rubbing two sticks together. The folks who have posted "smoldering telescope" stories today must be mistaken. It's so unlikely that statistically, it didn't happen. And if it did, they should deny it. ;) --- diveboss@xmission.com wrote:
Brent, a nit picker??? ;)
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Wow, I guess I have "Incredible Deniability" now! :) Must be time to go into politics.... At 07:20 PM 9/30/2004 -0700, Chuck wrote: Clipped
The folks who have posted "smoldering telescope" stories today must be mistaken. It's so unlikely that statistically, it didn't happen. And if it did, they should deny it. ;)
If you would like, I will run your campaign... ;) Quoting Josephine Grahn <bsi@xmission.com>:
Wow, I guess I have "Incredible Deniability" now! :) Must be time to go into politics....
At 07:20 PM 9/30/2004 -0700, Chuck wrote: Clipped
The folks who have posted "smoldering telescope" stories today must be mistaken. It's so unlikely that statistically, it didn't happen. And if it did, they should deny it. ;)
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I instantly regretted sending my last post, even as I was hitting "send". That last statement sounded too trite, even for me. Look, here's what I am saying: A telescope mirror CAN start a fire. To be fair to Brent, yes it is unlikely, and the longer the focal length, the less concentrated the hot spot (which is just the prime focus solar image). You can play with f-ratio and aperture and find some combinations hotter than others to be sure. This really is overanalyzing a basically intuitive situation. I have purposely started fires with mirrors from 10" to 17.5", f-ratios from f/4.5 to f/6. Sometimes it isn't instantaneous...how long it takes depends also on the nature of the tinder in terms of ignition point, heat retention, etc., probably other conditions that the slide-rule types can easily come up with effortlessly but I'd have to dig out 25 year old textbooks to pull it together. You don't hear much about telescope or optically caused fires, but they do happen. We have friends who lost their house to a fire caused by sunlight being focused on a curtain by glass sculpture! Art causing a fire! So now that this dead horse (sorry Rich, poor choice of words) is thoroughly beaten, there it is. Can happen, but usually only as a fluke occurrence if unintentional. And my apologies to Brent for suggesting a pathological fastidiousness. Sorry, home today with a sick kid, time on my hands. _______________________________ Do you Yahoo!? Declare Yourself - Register online to vote today! http://vote.yahoo.com
I bought an F-4 canopy from Smith and Edwards last year to build a flight simulator for my Grandkids. They (Smith and Edwards) said that they would have had a larger selection, but the Sun shinning though one canopy started a fire in their yard. I know this isn't telescope related, it does demonstrate a sun caused accidental fire. Wayne Ps as long as I'm using band space, Dale Hooper, it looks like I moving to 359 N 1000 E, Hyde Park, anywhere near you? -----Original Message----- From: utah-astronomy-bounces+waynereese=qwest.net@mailman.xmission.com [mailto:utah-astronomy-bounces+waynereese=qwest.net@mailman.xmission.com ] On Behalf Of Brent Watson Sent: Wednesday, September 29, 2004 10:36 AM To: Utah Astronomy Subject: RE: [Utah-astronomy] Re: Starpartyetiquetteforcrumbcrunchersandparents Starting a fire is just as unlikely off axis as well. The light cone doesn't change much off axis, and most folks don't park their scopes within a focal length of tinder. If they did they wouldn't have much of the sky visible. You must also have a fast enog=ugh scope to start the fire. The focal ratio required to do this is much smaller than most scopes. You really have to try to do any damage. The reticle in a Telrad doesn't catch fire, it just melts - a much lower temperature is required to melt mylar than to burn something up. There is a tale that one of the ancients started the sails of his oponents ships on fire by stationing his troups around the bay with individual mirrors, and then having them focus their mirrors on the sails. It has been shown that this too is very improbable. Brent --- Chuck Hards <chuckhards@yahoo.com> wrote:
Lisa, read my last post. Yes, you CAN start a fire with a telescope mirror, it's just unlikely on-axis unless tinder is very near the focal plane.
Eyepieces left on a chart table can do the trick, too, and tell all those folks with melted Telrad reticles that the sun isn't a problem.
I would like to see John's calculations, assumptions.
I have several large mirrors and am happy to demonstrate the off-axis danger on a sunny day.
--- John and Lisa Zeigler <john@johnstelescopes.com> wrote:
Ya, John did the physics of it for me last night and figured out exactly what diameter mirror at what focal length you would need to start a fire. Let me tell you, it aint going to happen! Sometimes its difficult living with an over analyzer. I just meant it figuratively.
Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com
-----Original Message----- From: Brent Watson [mailto:brentjwatson@yahoo.com]
Sent: Wednesday, September 29, 2004 7:52 AM To: Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star partyetiquetteforcrumbcrunchersandparents
The forest is no more at risk from a alrge scope than from a small scope. It is pretty hard to get enough energy out of a scope and across a distance large enough to do any damage. The image, and the energy in the image, spread out very quickly and become a non-problem.
Brent
--- John and Lisa Zeigler <john@johnstelescopes.com> wrote:
We have a 1/4" plywood shield over our mirror on the truss tube Dob. It sits about an inch over the mirror on three screws from the mirror cell. This protects it from wind, rain, dust, and the forest from harm.
Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com
-----Original Message----- From: Debbie [mailto:astrodeb@earthlink.net] Sent: Tuesday, September 28, 2004 1:17 PM To: Utah Astronomy; Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star party etiquetteforcrumbcrunchersandparents
That is another reason I don't like to leave my scope up during the daytime, besides animals getting to it. A big dobsonian could cause a forest fire or blind someone.
Debbie
[Original Message] From: Patrick Wiggins <paw@trilobyte.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Date: 9/28/2004 11:10:18 AM Subject: [Utah-astronomy] Re: Star party etiquette forcrumbcrunchersandparents
I seem to remember many years back a star party up by Kamas where Brent's monster scope ended up catching a frisbee or two. But then I seem to also remember that later in the day the scope became a chimney
when sunlight found its way to the primary mirror and smoke was seen emanating from the tube...
Patrick
Chuck Hards wrote:
Don't be so sure; I've seen many telescopes
(present company
excepted, of course) that may as well have been trash-cans...
--- John and Lisa Zeigler <john@johnstelescopes.com> >
Solid tube Newtonian telescopes, no matter how much they look like > trash cans or basket ball hoops are not for throwing things into..
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The forest is no more at risk from a large scope than from a small scope. It is pretty hard to get enough energy out of a scope and across a distance large enough to do any damage. The image, and the energy in the image, spread out very quickly and become a non-problem. Brent --- John and Lisa Zeigler <john@johnstelescopes.com> wrote:
We have a 1/4" plywood shield over our mirror on the truss tube Dob. It sits about an inch over the mirror on three screws from the mirror cell. This protects it from wind, rain, dust, and the forest from harm.
Lisa Zeigler www.johnstelescopes.com www.mirrorkits.com
-----Original Message----- From: Debbie [mailto:astrodeb@earthlink.net] Sent: Tuesday, September 28, 2004 1:17 PM To: Utah Astronomy; Utah Astronomy Subject: RE: [Utah-astronomy] Re: Star party etiquetteforcrumbcrunchersandparents
That is another reason I don't like to leave my scope up during the daytime, besides animals getting to it. A big dobsonian could cause a forest fire or blind someone.
Debbie
[Original Message] From: Patrick Wiggins <paw@trilobyte.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Date: 9/28/2004 11:10:18 AM Subject: [Utah-astronomy] Re: Star party etiquette forcrumbcrunchersandparents
I seem to remember many years back a star party up by Kamas where Brent's monster scope ended up catching a frisbee or two. But then I seem to also remember that later in the day the scope became a chimney
when sunlight found its way to the primary mirror and smoke was seen emanating from the tube...
Patrick
Chuck Hards wrote:
Don't be so sure; I've seen many telescopes
(present company
excepted, of course) that may as well have been trash-cans...
--- John and Lisa Zeigler <john@johnstelescopes.com> >
Solid tube Newtonian telescopes, no matter how much they look like
trash cans or basket ball hoops are not for throwing things into..
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Brent, the danger is more from the exposed mirror on the typical large truss-tube Dob; the reflected hot spot isn't necessarily on-axis and can end-up just about anywhere. So perhaps a large scope isn't more dangerous just because of size, but they are more likely to be trussed and thus have an exposed primary. Brent Watson <brentjwatson@yahoo.com> wrote:
The forest is no more at risk from a large scope than from a small scope. It is pretty hard to get enough energy out of a scope and across a distance large enough to do any damage. The image, and the energy in the image, spread out very quickly and become a non-problem.
Brent
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participants (7)
-
Brent Watson -
Chuck Hards -
Debbie -
diveboss＠xmission.com -
John and Lisa Zeigler -
Josephine Grahn -
Wayne Reese