They vary by how many features they offer and how pretty they are. Used camera prices depend on how good the camera was to start with and how pretty it was. Also, they have to be able to create a image that's wider than the negative to allow for the movements. See Question 8 for more about used lenses. C. Film holders.
Sheet film has to be held in place by a film holder.
Typically these are little light-tight boxes with removable dark slides. You load the film into the holders in the dark and put the dark slide in place. This makes them light-tight. You then put the holder into the camera back, remove the darkslide, and expose the film. D. Heavy-duy Tripod.