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Amazon (and Ebay?) flooded with unsafe eclipse viewers?
On 16/08/2017 08:36, StarDust wrote:
On Tuesday, August 15, 2017 at 8:29:07 PM UTC-7, RichA wrote: On Tuesday, 15 August 2017 12:41:43 UTC-4, Mike Collins wrote: On Monday, August 14, 2017 at 8:56:06 AM UTC-7, RichA wrote: 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. But, what can you see with it? Exposed low speed silver halide films like Pan-X were dense enough to give a good view. Use to have a small welding mask, used that once or twice for eclipse viewing, it was pretty good. Eleectric arc welding glass gives a nice green image although any spatter on the front side of the shield interferes with the view. Prisine unused dense welding arc filter is best. -- Regards, Martin Brown |
#12
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Amazon (and Ebay?) flooded with unsafe eclipse viewers?
On Wednesday, 16 August 2017 03:32:48 UTC-4, Martin Brown wrote:
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 As far as I know, there is no black and white slide film on the market today. Everyone who thinks film think negative. |
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