I think the first company that got really mad was Goodyear, because they're famous for using blimps.
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A H(ydrogen)-Alpha filter is a special lens used for viewing the Hydrogen-Alpha wavelength of light through telescopic or photographic devices. It works by filtering out all wavelengths of light except the red spectral line associated with hydrogen. This is commonly used to see shape and structure of objects that emit said light (namely, our own sun, and various nebulae as mentioned in the text).
Many earlier designs for airships (including the ill-fated Hindenburg) used (highly flammable) hydrogen gas for lift due to both its lower cost and higher availability. After the Hindenburg disaster designers switched exclusively to helium or heated air for lift. I The Hindenberg was supposed to be using Helium, but the USA was the prime producer at that time and for some reason refused to supply Germany at the time. This forced the use of Hydrogen, with the regrettable result. Choice of exterior paint, the gas 'bag' design being too permeable and lack of earthing were also factors. RIIW - Ponder it (talk) 20:27, 3 July 2021 (UTC)
Metropolitan Life Insurance Company (AKA MetLife) is an insurance company that licensed the Peanuts characters, In particular, Snoopy in their advertising. They featured the Snoopy character in his alter-ego role of World War I Fighter Ace (which frequently fought with the Red Baron in the Charles Schulz comics) in both print and television ads between 1985 and 2016, and most notably pictured on some of their advertising blimps. 18.104.22.168 06:29, 3 July 2021 (UTC) Not the Red Baron
Many nebulae contain excited hydrogen atoms emitting the Hα wavelength, so a Hα filter is useful for removing other light such as light pollution, making nebulae stand out in photographs.
In most cases when a sun filter is mentioned, it's probably a white-light filter that only reduces the light intensity. A Hα filter is used to highlight the sun's chromosphere – the layer above the sun's apparent "surface", the photosphere.
I'm not sure whether the same filters are actually used for photographing both the sun and nebulae. 22.214.171.124 11:52, 3 July 2021 (UTC)
I think someone should edit the summary to detail two points: One, that blimps are not the same as zeppelins. The latter has a rigid body and tanks of gas, rather than the former's balloon body. And two, airships such as the Hindenburg were never designed to be flown using hydrogen; it would have continued to use helium on that one fateful flight if it had not been for a trade embargo on Germany for the gas from its largest supplier, the United States.
I don't believe blimps have really ever been flown with hydrogen, but someone who knows better should add it. 126.96.36.199 20:02, 4 July 2021 (UTC)
About the Warning: i don't think that a filter has the ability, to hurt anyone. Therefore it should be rephrased, that the remaining sunlight will still hurt you eyes. 188.8.131.52 13:10, 5 July 2021 (UTC)
The solar filter in 1828 is surely not a hydrogen-alpha filter. The picture of the sun in that strip doesn't show the deep red hydrogen-alpha color, and it doesn't make sense to set the white balance while using a narrow-band filter. 184.108.40.206 20:08, 10 July 2021 (UTC)