Comment by yawpitch
> A simple image amplified and focused by hand, through delicate rotations of plates of glass, and filtered toward a tiny mirror contained inside a camera that projected the reflection toward a viewing screen. When Karsh opened the shutter for one-tenth of a second, he exposed an eight-by-ten sheet of light-sensitive nitrocellulose Kodak film to the reflection of Winston Churchill, creating a negative that later needed to be developed in darkness.
Karsh used an 8x10” monorail camera… there were no “delicate rotations of plates of glass”, such cameras don’t use helical focusing, instead a lens with fixed optical glass is moved back and forth using linear movements of either or both of the vertical stanchions.
There also is no “tiny mirror” reflecting anything… while (a very few) 8x10” reflex cameras have been built, they require an 8x10” mirror, and in any case this wasn’t a reflex camera at all. Karsh would have set the rough focus by moving the rear stanchion sufficiently far from the front stanchion to get rough focus at that distance from the film plane with the lens he was using, then he would have achieved fine focus by viewing a ground glass plate slightly larger than the negative set in the rear stanchion, light projected directly through the lens onto that ground glass forming an image flipped both vertically and horizontally from reality (Churchill’s head would have been on the bottom and any text on the cigar would have been flipped left to right)… no mirror of any size was involved. Once focus was set a light tight film back was inserted, replacing the ground glass with a sheet of film at the same distance from the optical center of the lens, hence the same focal distance. The lens’s shutter would then have been closed, a dark slide would have lifted to allow light to strike the film, and then the exposure was ready to be taken whenever Karsh (and Winston) were ready (-ish, in the case of Winston).
Lastly all film negatives, sheet or otherwise, had to be developed in the dark… the thing that made nitrocellulose special was that it really needed to be developed and stored away from flame.
About a year ago, I had an opportunity to use an 8x10 field camera. This description is correct. I didn't have any film, so I loaded the film holder with paper and developed it under a safelight in the darkroom. This isn't a typical process though and film has very low ISO. I then contact printed through the paper. The resulting image wasn't particularly sharp. It was a fun exercise though, and I'd like to borrow the camera again. Using it is a very slow and formal process. The film is as one would expect, expensive.