I just recalled something pertinent to this thread. Way back when I was shooting 35mm, I noticed that the frames sometimes had a narrower space between them than other frames, making it more difficult to cut the strips. I finally discovered that the narrow spaces occurred when adjacent frames were made using wide angle lens, and longer lenses left wider spaces. The camera's "mask" in front of the film was a constant width and a finite distance from the film. When a wide angle lens was used, being closer to the film, it projected a wider image onto the film (wider than the mask).