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.
I was wrong. The sodium vapors and the torch plume are in one unified stream. If the flame was different before and after the glass it would be a valid theory.
Looking at the picture, my theory may be wrong. There is a black spot on the torch too far from the hot glass. (Maybe some hot glass dripped on the torch?)
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 only cover over the flame so the area 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.
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.I was wrong. The sodium vapors and the torch plume are in one unified stream. If the flame was different before and after the glass it would be a valid theory.
https://www.youtube.com/watch?v=_fI3gpO5hW4
Looking at the picture, my theory may be wrong. There is a black spot on the torch too far from the hot glass. (Maybe some hot glass dripped on the torch?)
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 only cover over the flame so the area 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.