Erik, There are a lot of folks who are very concerned about damage to their cameras from the sun. I have a question though. When using their cameras for noraml photography, how many times do they catch the sun in the image and yet no damage occurs? The next comment would be that eclipse photography is different because the sun s larger and therefore covers a bigger portion of the shutter/image sensor. It is the same sun, but now the same amount of energy is spread across a larger area so the energy per area is less by the factor of the image size squared, or the ratio of the focal lengths used squared. Is that still too much energy? How many images of th setting sun have you seen and yet there is no damage to the camera? Cutting the energy of the sun down by a factor of 7 (15% transmission) coupled with a focal length increase of 10X - another 99% reduction - and then using a very slow f stop - from f4 to f22 is a further reduction of 2^6, or 1/64 - one would reason to be OK. The total reduction there would be .15*.01*.0156 = .0023% would be sufficient. Do you see a hole in this logic? I know I have included the sun in many photographs I have taken with no damage to the camera nor shutter. Brent From: "erikhansen@thebluezone.net" <erikhansen@thebluezone.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Thursday, May 3, 2012 1:06 PM Subject: Re: [Utah-astronomy] Solar glasses
Brent,
I have searched the web for 52-48 mm solar filters, seems most ideas of solar filter for camera's, is a PST or like h-alpha filters. I am pondering wether or not a 15% transmission polarizing filter is enough to protect a digital camera (at some 95% blockage of the sun). Any thoughts? maybe paired with an H-alpha Blk&white filter. Erik Thanks Seth, but there wasn't much new there, nor did it really answer my
question. I guess I'll fall back to my original plan of building an adapter for my 4" glass filter for use on my camera.
From: Seth Jarvis <SJarvis@slco.org> To: 'Utah Astronomy' <utah-astronomy@mailman.xmission.com> Sent: Wednesday, May 2, 2012 3:29 PM Subject: Re: [Utah-astronomy] Solar glasses
Hi Brent,
Have a look at a blog article written by Duke Johnson, our Education Manager (and an accomplished astrophotographer) on the subject.
http://clarkplanetarium.org/photographing-the-may-20-annular-eclipse/
Good luck!
Seth
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Brent Watson Sent: Wednesday, May 02, 2012 3:04 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Solar glasses
Seth, Do you have solar filters for cameras? I am looking specifically for a 52 mm white light or Halpha filter. Thanks, Brent
From: Seth Jarvis <SJarvis@slco.org> To: 'Utah Astronomy' <utah-astronomy@mailman.xmission.com> Sent: Wednesday, May 2, 2012 2:41 PM Subject: Re: [Utah-astronomy] Solar glasses
We carry the Orion full-aperture glass filters. For a 10" Dob it would be about $160.
If you've got that kind of money burning a hole in your pocket, more power to you and you'll love it.
BUT, I question the need for that much of a filter.
A far less expensive and probably just as useful solar filter could be made using a 4" off-center hole covered with Baader Astro Solar Safety film in a cardboard disk over your scope. I know there's been plenty of discussion on this topic in these messages.
We've just sold out of the full-aperture glass filters for 8" and 10" Dobs, but Orion tells us they'll have more here in plenty of time for the eclipse. If I had a nice 10" Dob, I'd get the Baader filter and make an off-center "solar filter dust cover" for my scope. I suspect there's no shortage of people here who can tell you about how to make one.
Seth
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of william baker Sent: Wednesday, May 02, 2012 1:50 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Solar glasses
Seth, What is the cost for a solar filter for an Orion 10xt Dobsonian?
________________________________ From: Seth Jarvis <SJarvis@slco.org> To: 'Utah Astronomy' <utah-astronomy@mailman.xmission.com> Sent: Wednesday, May 2, 2012 12:34 PM Subject: Re: [Utah-astronomy] Solar glasses
Ann,
We sell solar eclipse glasses here at the planetarium for $1.95 per pair. Yes, you can get them for less online but you have to buy them in bulk as Wayne did.
We bought a lot of them in anticipation of public interest in both the eclipse and the transit of Venus on 6/5. People with good vision should be able to see Venus on the Sun with just the solar eclipse glasses. It'll be about the size of a medium sunspot.
The $1.95 eclipse glasses work great - they're made specifically for looking at the Sun.
We also sell glass solar filters for telescopes and binoculars - the same items you get online from Orion.
Also, you could go to a welding supply company and buy Grade #14 welder's helmet glass filter plate. It must be Grade 14 (they call it "shade 14") or higher to be safe. Costs about $4 for a 4" x 5" plate. The Sun is a lovely shade of green through these.
No, you can't combine two #7's to achieve the same result. Doesn't work that way.
Seth
-----Original Message----- From: utah-astronomy-bounces+sjarvis=slco.org@mailman.xmission.com [mailto:utah-astronomy-bounces+sjarvis=slco.org@mailman.xmission.com] On Behalf Of Ann House Sent: Wednesday, May 02, 2012 10:40 AM To: Utah Astronomy Subject: [Utah-astronomy] Solar glasses
I am looking to purchase solar glasses for the transit and the eclipse. They are about a dollar each which worries me somehow. While I don't want to pay more than is necessary, I am wondering - really? - can I trust my eyes to be safe for a dollar? Thoughts?
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