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Old August 16th 17, 08:32 AM posted to sci.astro.amateur
Martin Brown[_3_]
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Default Amazon (and Ebay?) flooded with unsafe eclipse viewers?

On 16/08/2017 04:29, RichA wrote:
On Tuesday, 15 August 2017 12:41:43 UTC-4, Mike Collins wrote:
StarDust wrote:
On Monday, August 14, 2017 at 8:56:06 AM UTC-7, RichA wrote:
http://money.cnn.com/2017/08/13/news...nds/index.html

Note it appears the black polymer Baader film might not be suitable for
eyes-only eclipse viewing too.

LOL! I remember back in the old days, use to hold a piece of glass over a
candle to cover it with soot than use it to view the eclipse.
After 40 years, I still have 20/20 vision!


For the first solar eclipse I can remember my teacher gave every pupil a
piece of blotting paper with a needle hole in it. We watched the eclipse
through the hole.
For the next eclipse the teacher (not the same one) gave us all folded
black and white film negatives.


Fully exposed (blackened) black and white (as opposed to colour) film negatives are a safe viewing device, apparently. No, chromogenic black and white aren't suitable.


Unexposed slide film is particularly dangerous as it can lower the
visible light to an almost comfortable level but lets through dangerous
amounts of near infra red. If you ever have a strip of the stuff it is
interesting to look through it at the natural world around you. When the
eye has dark adapted sufficiently after a minute or two the colour
vision slowly returns but with additional sensitivity in the near IR.

There are no pain receptors in the back of the eye so it doesn't hurt at
the time - only ~6 hours later. Crescent shaped eclipse retinal burns.

--
Regards,
Martin Brown