Solar Eclipse Viewing Tip

18 Comments
Reads 27942

By Alonzo

With all of the hubbub about eclipse eye protection I want to add that old fashioned photo negatives work really well. Stack 3-4 of them to start, then remove one or two if necessary until the eclipse
is clearly visible without hurting the eyes.
 

Update by an edhat reader

NASA is recommending against this method, it is WAY too variable and can easily cause permanent blindness 

Unsafe filters include all color film, black-and-white film that contains no silver, photographic negatives with images on them(x-rays and snapshots), smoked glass, sunglasses (single or multiple pairs), photographic neutral density filters and polarizing filters.
 
Login to add Comments

18 Comments

Toggle Comments (Show)
a-1511568835 Aug 17, 2017 04:45 PM
Solar Eclipse Viewing Tip

Add a huge lack of critical thinking ability to large doses of ignorance and gullibility, and you get people like Faker, who live in a world of delusions. The irony of it all is that science has provided people like this with a support system that allows them to live their lives knowing only how to pump gas and work a TV remote.

yourfakereality Aug 17, 2017 03:44 PM
Solar Eclipse Viewing Tip

At the risk of becoming a target all sorts of abusive personal attacks, as well as a possible restricted membership or even a ban, I am COMPELLED to point out that NASA is NOT a reliable source of information. In fact, there is a community on Youtube that has done extensive analysis of material NASA has released to the public over the years, and the evidence strongly suggests that "manned space flight", as well as "outer space" are nothing more than science FICTION. Please do not try to dismiss this as "ignorance" - many in the Truth movement are highly educated and originally approached this subject with the aim of debunking the "NASA doubters" - that's pretty much the direction I came from - my dad was an engineer with Martin Marietta (now known as Lockheed Martin) in the Mercury & Gemini programs, and spent his entire career launching Titan missiles with Martin. I did NOT want to believe "space" is just a hoax, but the truth cannot be debunked. If this makes you angry, it should, but please don't waste your time attacking me - if you think I'm wrong, don't be childish, prove me wrong with actual evidence. There are hours of video on Youtube showing so-called astronauts simulating zero gravity with harnesses, cables, green screens, and the "Vomit Comet", so good luck debunking any of it...

a-1511568835 Aug 17, 2017 05:17 PM
Solar Eclipse Viewing Tip

The best phrase describing such thinking is attributed to Wolfgang Pauli: "not even wrong".

Flicka Aug 17, 2017 09:31 AM
Solar Eclipse Viewing Tip

The posted information did say you need film with silver. I will be satisfied to watch on TV. I remember being on Miramar Beach and seeing a partial eclipse. Long, long ago, I was a little kid and looked directly at it. We didn't know any different then, at least my cousin and I didn't. Luckily, no damage.

mtndriver Aug 16, 2017 01:32 PM
Solar Eclipse Viewing Tip

I hope we have a clear morning! Cloudy every day this week til well after noon.

a-1511568835 Aug 16, 2017 12:08 PM
Solar Eclipse Viewing Tip

Can't believe this is posted...DO NOT DO THIS. Straight from NASA: Unsafe filters include all color film, black-and-white film that contains no silver, photographic negatives with images on them (x-rays and snapshots), smoked glass, sunglasses (single or multiple pairs), photographic neutral density filters and polarizing filters. Most of these transmit high levels of invisible infrared radiation which can cause a thermal retinal burn (see Figure 24). The fact that the Sun appears dim, or that you feel no discomfort when looking at the Sun through the filter, is no guarantee that your eyes are safe. https://eclipse.gsfc.nasa.gov/SEhelp/safety2.html

John Wiley Aug 16, 2017 11:59 AM
Solar Eclipse Viewing Tip

I recall having safely viewed the sun outdoors larger and more clearly than with the pinhole method by projecting it onto the sidewalk with one side of ordinary binoculars in reverse. It would presumably work fine with a telescope backward too. I taped the binoculars to a tripod and found that the image would focus about 3 feet away. This was during a previous partial eclipse, and it was fascinating to see sunspots so large and clear. The image was large and even in sunlight, bright enough to see easily. I'm going to try it again once the sun comes out, and might post a followup comment here with details. Since this eclipse is mid-morning I might get better results than using the sidewalk by shining it onto a piece of white cardboard held perpendicular to the sun.

John Wiley Aug 16, 2017 05:34 PM
Solar Eclipse Viewing Tip

Also forgot you have to reload after posting to see it (hence double comment above :)

John Wiley Aug 16, 2017 05:33 PM
Solar Eclipse Viewing Tip

Wow what a blob of text. Forgot the new Comments option strips out paragraphs. :(

John Wiley Aug 16, 2017 05:33 PM
Solar Eclipse Viewing Tip

Wow what a blob of text. Forgot the new Comments option strips out paragraphs. :(

John Wiley Aug 16, 2017 05:32 PM
Solar Eclipse Viewing Tip

OK, turns out I recalled the opposite. The binox point toward the sun as you'd do to look at it and vaporize your retinas (obviously, don't do that!). Mounted some feet from the sidewalk the sun's image crosses the eye focal point to appear reversed and about 5" across on the sidewalk. Main advantage over pinhole is vastly brighter image. After the sun came out, at about 3pm-ish I dug out the old binox I used in a prior eclipse. They're 10x50 with 2" main lenses (smaller 8x35 binox made the sun dimmer and about 4" across, and cheapo 10x25 binox made 5" image but you'd need a cloth shroud to darken background for clear viewing). I set up a flimsy tripod about 43" high (will use a heavier one for the eclipse, but it worked w/o wind). I used 4 little hair scrunchies to put the binox on it, tho of course Duct Tape would be the manly method. At the 3:15ish sun angle, the sidewalk focal point was about 53" away but of course the top & bottom of the oblong sun image were a bit out of focus and the grain of the sidewalk ruins the clarity. I set a sheet of paper up on an old laptop to hold it perpendicular to the sun and that allowed better focus but still had uneven brightness & texture. I found a piece of matte white plastic and shining the image on that made the sunspots sharper. On the flimsy tripod it was impossible to get really sharp focus, but I could still make out sunspots. With some fiddling it might even be possible to move the binox farther away and get the image big and sharp enough to see the corona - especially where there's a total eclipse, tho there's lens chroma distortion so maybe way under-exposed pix would reveal it. Of course, closer = brighter and the distance range is probably limited by the focus range of the binox. The image was plenty bright in the shade. I put the binox at the edge of shade and angled the image slightly out of their shadow so it's in the shade (probably sharper to align binox shadow w/image center, then use cardboard with a hole for the binox to shade the image area or drape black cloth around the sun image). Lacking lens cap I put wide blue painter's tape over one lens but you could use anything (sock?) to block it and prevent image overlap. The hardest part was aligning the binox to the sun, and I found it easier to start w/paper held near the binox so I could move them to find an image and then fine-tune it on the ground. The whole exercise took about an hour, from digging out the bits to putting it all away. The binox didn't get warm at all, and it doesn't seem like anything inside would since it's a path thru clear glass once aligned. Presumably a star-tracking motorized telescope mount would be nice, tho maybe it would melt telescope innards as warned by someone here. I'm glad to have tried this in full sun so it'll be quick to repeat for the eclipse. Now the question is whether we'll have clouds (and if not - whether to fly somewhere there's sun).

macpuzl Aug 16, 2017 12:44 PM
Solar Eclipse Viewing Tip

Use old binoculars. The heat buildup may damage eyepieces with cemented optics.

a-1511568835 Aug 16, 2017 12:16 PM
Solar Eclipse Viewing Tip

Now THAT is a great solar eclipse tip. I will be trying this one!

macpuzl Aug 16, 2017 11:43 AM
Solar Eclipse Viewing Tip

One problem with the "doesn't hurt" advice is that your retina has no pain sensors. The pain you might feel is from the muscles attempting to contract your pupils in the presence of bright visible light. Infrared light leaked by a poorly-made filter will burn your retina, but your pupil doesn't respond to infrared, so you can damage your vision without feeling any pain. Better to play it safe with your eyes, and use only projection or ISO-certified filters.

macpuzl Aug 16, 2017 11:31 AM
Solar Eclipse Viewing Tip

Even better than risking your vision with homebrew experiments is to view the eclipse through safely filtered viewing devices at the public observations at SBMNH, MOXI, or Camino Real Marketplace, 9 AM to noon on Monday. The SBAU and SBMNH will have free ISO-certified viewing glasses available, while supplies last. An absolutely safe projection device can be made from card with an aperture covered by tinfoil. Poke a pinhole in the foil, and project the Sun's image onto a flat surface. Multiple images are produced using a colander or card with small holes spelling your name. More here: http://www.skyandtelescope.com/astronomy-news/how-to-look-at-the-sun/

a-1511568835 Aug 16, 2017 09:09 AM
Solar Eclipse Viewing Tip

details for using film negatives:You can make your own filter out of black-and-white film, but only true black-and-white film (such as Kodak Tri-X or Pan-X). Such films have a layer of silver within them after they are developed. It is this layer of silver that protects your eyes. To make your own solar filter, proceed as follows.Open up a roll of black-and-white film and expose it to the Sun for a minute. Have it developed to provide you with negatives. Use the negatives for your filter. It is best to use two layers. With this filter, you can look directly at the Sun with safety. Remember, however, that if you are planning to use black-and-white film as a solar filter, you need to prepare it at least several days in advance. Caution: Do not use color film or chromogenic black-and-white film (which is actually a color film). Developed color film, no matter how dark, contains only colored dyes, which do not protect your vision. It is the metallic silver that remains in black-and-white film after development that makes it a safe solar filter.

Please Login or Register to comment on this.