Hee, hee. That is a good one Joe. I thought maybe the person on the bottom bunk might not be so happy! 73, lh On 5/12/2012 4:12 PM, Joe Bauman wrote:
I meant to say they are designed for BINOS, but the automatic spell check changed it to bunks! Sorry. -- Joe
________________________________ From: Joe Bauman<josephmbauman@yahoo.com> To: utah-astronomy@mailman.xmission.com Sent: Saturday, May 12, 2012 1:31 PM Subject: Re: [Utah-astronomy] Eclipse eye safety
Thanks, Erikhansen -- these solar filters are designed for bunks so that's Ok. -- Joe
------------------------------ On Sat, May 12, 2012 1:17 PM MDT erikhansen@thebluezone.net wrote:
The only issue I can think of is wether or not it is a visual or photographic filter being the photographic filters are unsafe for visual use.
What I was most concerned about is that the diameter of the lens is the same as mine, so it has the same light-gathering capacity. But because the focused image is smaller the light hitting his Reyna will be more concentrated per area. We want to avoid any eye damage. Thanks -- Joe
------------------------------ On Sat, May 12, 2012 1:00 PM MDT Seth Jarvis wrote:
Joe,
If I understand your question correctly you just want to cover a new camera lens that has the same objective lens diameter as you binoculars and your 400 mm telephoto lens. It shouldn't be a problem. The surface area is the same, so the filtering per square mm is still the same.
Your friend's lens will produce a smaller image of the Sun, but there won't be any more total photons in the optics than with your 400 mm lens.
If there is a difference it will be with how the film or ccd handles large changes in brightness across the image arising from the smaller Sun in the image.
It should be like changing eyepieces on your telescope - what you gain in magnification you lose in brightness, and vice-versa.
If anyone here understands the question differently and thinks I'm wrong, please let us know.
And by all means, experiment! Evidence beats theory every time.
Seth
On May 12, 2012, at 12:15 PM, "Joe Bauman"<josephmbauman@yahoo.com> wrote:
Hi All, I have a question that one of you may be able to answer: I bought a pair of solar filters for binoculars, at the planetarium. As expected, they work great with my 400 mm. telephoto lens. We are traveling to Newcastle for the eclipse with a couple of friends, and I want to lend him one of the filters for his camera. However, his camera's lens is 135 mm. instead of the 400 mm. of mine, which means the image of the sun would not be as large as in my setup. Would the fact that the sunlight is more concentrated pose a danger to either Aaron's eye (as he looks through the viewfinder, since the camera doesn't have a live screen view) or to the camera itself? That seems unlikely to me because presumably many binos are about that size. Also, the rim of the filter fits over my telephoto, but Aaron's is exactly the same diameter as the rim. Almost certainly it would be safe to tape it on super-well so that no light could get in at the edge, and so that the filter can't fall off, but I thought I would seek the advice of people who know more than I do. Thanks, Joe _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy
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