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Comment on Im watching an episode of Mr. Rogers Neighborhood, filmed in black and white. In this scene a guest is showing glass making. What is going on with the film to make these black areas by the flame?

lefixxx@lemmy.world ⁨3⁩ ⁨weeks⁩ ago

Hot glass emits sodium vapors. Sodium vapors block the wavelength of the light that the film is sensitive to. The torch emits on wider spectrum so the torch flames are leaving an impression on the film.

Glassblowers didymium goggles block the torches spectrum but can’t hide the hot sodium emitting light. The hot gas that you can see when looking though glassblowers goggles is what looks black in your photo.

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lefixxx@lemmy.world ⁨3⁩ ⁨weeks⁩ ago
www.youtube.com/watch?v=_fI3gpO5hW4

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lefixxx@lemmy.world ⁨3⁩ ⁨weeks⁩ ago
Looking at the picture, my theory may be wrong. There is a black spot on the torch too far from the hot glass.

My other theory is that the flames where so bright they had to edit the footage. Old film developers had a technique to darken an area called “burning”. It was not so precise to cover over the flame so the are around the bright spots got darkened as well.

Modern HDR can have a similar effect. When an algorithm can’t be sure of how dark an area between a dark and a bright spot must be, it make the transition gradually causing the “HDR Effect” where, for example, the sky gets brighter the closer you get to the horizon, building, subject.

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