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Featured Stargazing U.S. Solar Eclipse of Aug. 21, 2017

  1. Jun 29, 2017 #141
    As long as they are not compromised from storage, I would expect them to be just fine.

    If they are torn, creased, or otherwise compromised in the lenses, I would dispose of them, even if they are a souvenir, so that no one in the future (little kids) get a hold of them, and try to use them.

    However, if you have taken care to make sure they made the 18 year journey unscathed, I would expect them to be just fine. On August 22, mine will go into a hard case, and my sock drawer. The 2024 eclipse is only 6-2/3 years, and 90 minutes from home - if I'm alive, I intend to be there with my kids, and (maybe) grand kids.

    If anyone is interested in joining us near Makanda Illinois for an eclipse party, check out the thread at: https://www.physicsforums.com/threads/solar-con-eclipse-road-trip-to-makanda-illinois.914983/
     
  2. Jun 29, 2017 #142
    Thanks! It makes a lot of sense.
     
  3. Jul 5, 2017 #143

    Borg

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    I picked up three pair last week and looked directly at the sun with one yesterday. It appears to work well since I can still see. :smile:
     
  4. Jul 5, 2017 #144
    That's what I always wear everyday ...
     
  5. Jul 5, 2017 #145
    Perhaps that explains those nasty bruises on your forehead?... :smile:
     
  6. Jul 5, 2017 #146
    Gee thanks! ...
     
  7. Jul 14, 2017 #147

    1oldman2

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  8. Jul 14, 2017 #148

    mfb

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    The Concorde did that for more than an hour in 1973.

    An F-22 Raptor could probably stay in the shadow for about an hour as well.
    SR-71 Blackbird could have stayed in the shadow as long as it had fuel, but the model is retired.
     
  9. Jul 14, 2017 #149

    1oldman2

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    From the U.T. article.:thumbup:

    Should throw this in also.
    Airborne total solar eclipse chasing goes all the way back to August 19th 1887, when Dmitri Mendeleev (he of the periodic table) observed totality from aloft. There’s a great old video of an effort to chase a 1925 total solar eclipse using the airship the USS Los Angeles:
     
    Last edited: Jul 14, 2017
  10. Jul 16, 2017 #150

    OmCheeto

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    This is an fun video:



    I was mostly interested in the "Shadow Bands" discussion.

    ≈4:20 discussion begins about "Shadow bands"

    GMT; "...And if you're really lucky, you'll get to observe shadow bands. The shadow bands don't happen at every eclipse. ..."​

    ≈5:55
    SED; "How long does it last?"
    GMT; "For about 20 or 30 seconds."

    how to capture shadow bands:
    GMT; "Set up a camera on manual exposure on a king sized white sheet".

    On this last Memorial Day weekend, I went to a garage sale, and purchased TWO king sized white sheets, just for that purpose, for a dollar. (pat on back, pat on back)

    SED: Smarter Every Day, webcaster
    GMT: Gordon M. Telepun: Plastic Surgeon, Eclipse Fanatic, gives talks about "eclipses" at NASA.

    Anyone have any tips on how to capture "low contrast" images with a camera?
     
  11. Jul 16, 2017 #151

    1oldman2

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  12. Jul 17, 2017 #152

    OmCheeto

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    I checked.
    I could not find a "How to photograph white cows in a blizzard" article, but did see that "UV filters" used to be used for that purpose. I still have all of my old "film" developing junk, and found a UV filter.
    In the one article I read, it stated that digital cameras don't suffer from the "UV light confusing" the camera.
    After taking a couple of images with and without the filter, I can't tell a difference.
    I may have to read the manual for my camera. Please don't tell collinsmark. It's been over a year.....

    [edit: Nada. The camera has no special features in "movie" mode]

    ps. That linked thread is actually a setup for my next question.
     
    Last edited: Jul 17, 2017
  13. Jul 20, 2017 #153

    1oldman2

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  14. Jul 20, 2017 #154

    jim hardy

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    I read someplace that a #12 or #14 welder's helmet lens is a suitable filter.

    Hasn't been easy finding a table of attenuation vs shade number
    here's best i could do, from https://photo.stackexchange.com/que...-translate-to-stops-when-used-as-an-nd-filter
    weldingshade.jpg

    but the higher numbers are hard to find.

    My guess from transmittance numbers is that two #10's together will be not far from a #14... for visible that is
    transmittance of 0.0139 ^2 = 0.000193, which is 71% of a #14's nominal 0.00027
    UV is better by an order or two of magnitude ?
    so
    I bought two pair of #10's, with tax they cost me about five bucks each
    upload_2017-7-20_15-22-24.png



    when get a minute will see what they do to the sun.

    I figured it's safer than something home-made.
    If there's a welding optics guy in the house i welcome corrections .

    old jim
     
  15. Jul 20, 2017 #155

    OmCheeto

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    That is seriously interesting.

    "If you don’t think the danger is real, read this amazing recent interview with an optometrist on Space.com, where he states you can actually see the crescent Sun burned into the backs of patient’s eyes who stared too long at a partial solar eclipse (!) It’s a permanent souvenir you don’t want to have."

    But that brings up the question; "How long can you stare at the sun without getting a 'souvenir'?"

    After some googling, it looks as though there have not been enough volunteers for such a study, but;

    "Eclipse watching is the commonest cause of solar retinopathy..." [ref: British Journal of Ophthalmology]​

    :oldsurprised:

    Sunglasses, stained or smoked glass, and old film negatives do not protect against retinal damage following deliberate observation of the sun.
     
  16. Jul 20, 2017 #156

    OmCheeto

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    Ok. This looks like a reasonable answer.

    "...read this amazing recent interview with an optometrist on Space.com"

    While official recommendations by NASA and the American Astronomical society say you shouldn't look directly at the sun when any part of it is showing, experienced eclipse watchers like Chou say it's safe to remove your eclipse glasses during the 2-3 seconds before and after totality to see the so-called diamond ring effect, or "Baily's beads." During this phase of the eclipse, the light of the crescent sun forms points of light on the edge of the disk for just a few seconds.
     
  17. Jul 20, 2017 #157

    jim hardy

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    Two #10's make the afternoon sun just a pale yellow circle in a black field. It's so dim as to be barely visible so i'll have to rig some sort of face shield to block light from the sides. I think i'll look at welder's helmets .......

    One #10 is NOT enough .

    old jim

    Late entry

    got a welding helmet with #10 lens. Another lens taped on should work, will try it tomorrow..

    Hobart 770264 , $33 at Amazon $25 at Tractor Supply..
    upload_2017-7-20_21-42-11.png
     
  18. Jul 21, 2017 #158

    anorlunda

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    Uh oh. I just read this article about eclipse mania. They make it sound like this scene from the movie Contact.

    fIMfPvD.png

    It makes me fear that I may have seriously underestimated the logistics of seeing the totality. My wife and I are departing Vermont in the beginning of August for a 6 week car+tent tour of the US Northwest & Canada. The high point of the trip would be the eclipse. It is not our habit to plan anything in advance when we tour. We just follow our noses.

    I thought loosely that if we went to any remote area of Wyoming or Idaho or Oregon that we would have clear skies with no crowds. I did not plan to find a camp site within the zone of totality. But I thought we might be able to tent within 100 miles of the zone, and then drive in for the event and drive out again before dark. But in the remote areas, highways are also scarce. The approach roads might be jammed solid, and one can't find a private place behind a bush to pee. In short, my planning might be woefully inadequate.

    Counting only the American West. It seems like infinite wide open space, but not really. Let me do a little Drake equation.

    There are about 5 billion square meters of surface in the totality zone within 1000 miles of the Pacific. Optimistically, 1% of that is is within 200 m of a road. Figure 5 square meters per person including their car and chairs. There is room for only 10 million people, whereas 100 million people might be interested. Ay ay ay, it may get very crowded indeed.

    10 million people also need about 3 million toilet visits per hour. My wife and I are 72, we're no longer like Woodstock hippies.

    USA-WDSTK-2-1A.jpg

    One thing we won't do is to cancel. This is a chance of three lifetimes. I just hope that the news reports are greatly exaggerated.

     
    Last edited: Jul 21, 2017
  19. Jul 21, 2017 #159

    1oldman2

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    Quoting from the article, it's no wonder volunteers have been in short supply. (You would think a trained psychologist would know better than staring at the Eclipse long enough to blind himself.)
    "Don’t be like 18th century psychologist Gustav Fechner who blinded himself staring at the Sun, mesmerized by the glare of lingering afterimages."
     
  20. Jul 21, 2017 #160

    OmCheeto

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    If only it would be that peaceful. Just to be safe, I'm planning for a "Zombie Apocalypse":



    This has been me, every day, for quite some time.
    Just two weeks ago, I ran into a guy at our local renaissance faire. He was lugging around a $6000 camera/tripod setup. (He claimed the tripod cost more than his camera.)
    After about 5 minutes of conversation, I asked him where he was going for the "Eclocalypse".
    He said; "Fossil".
    Which is where I was planning on being.
    :oldcry:

    One glimmer of light is that I've found a multi-thousand acre ranch very near where I wanted to be, and they are only charging $150 per person, for a Thursday-Monday camp spot, and they only have 268 followers on Facebook. Which makes me suspicious, that they might be Russian hackers.
    http://www.mountaincreekeclipse2017.com/

    But I'm still going to wait on the weather report. I just discovered yesterday that I'm only a 19 mile bicycle ride away from the edge of totality.

    Furthest I'm willing to drive: 700 miles, Idaho Falls, Old Jim's place. Major cost: gas (≈$120)
    Middling place I'm willing to drive to: Mitchell Oregon, 200 miles. Cost: Ehr mehr gerd. 5 days of supplies, with self supplied solar heating & cooling, etc.... ≈$1000
    Bicycling distance: 19 miles. Might have to get up and leave by 5 am. Cost: New inner tubes. (guessing $10)

    [preemptive edit: Ehr mehr gerd......]



    These [russian hacker] kids might have a media agent.
    [/preemptive edit]
     
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