In the offset lithography process, the mechanicals would be photographed with a stat camera to create a same-size film negative for each printing plate required.
Paste up relied on phototypesetting, a process that would generate "cold type" on photographic paper that usually took the form of long columns of text.
Headlines and other typographic elements were often created and supplied separately by the typesetter, leaving it to the paste up artist to determine their final position on the page.
The photographs would be converted to halftone film separately and then positioned in this window to complete the page (although this process was typically performed by a different worker, known as a negative "stripper").
Once a page was complete, the board would be attached to an easel and photographed in order to create a negative, which was then used to make a printing plate.