Film is manufactured on huge rolls, and is cut down to different sizes and formats, so its not really that expensive on the manufacturing side to support a lot of formats. From the buy side, cameras are expensive, and almost all cameras only support one format. The big change came with film developing labs on teh high street, as when development was at home it was fairly manual, but once it was automated the machines were designed for fewer formats (for a long time 35mm, and often medium format). But even then, the process doesnt change per format and the chemicals are the same, so supporting variation is relatively cheap.

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jacquesm 10 hours ago | parent [-]

In the early days there were as many formats as there were camera backs because the exposure was at the size of the print. These were positives that were developed directly rather than that they went through an intermediate step of a negative and subsequent enlargement.

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justincormack 9 hours ago | parent [-]

The glass plate sizes were relatively well standardised, eg whole plate, half plate quarter plate, although other countries had metric and imperial versions. Before the plates were mass produced they may have varied more.

	▲	jacquesm 8 hours ago \| parent [-]
		My dad collected old cameras, he had 100's, and the number of formats in use was not all that much smaller than the number of cameras, to the point that we had to cut glass or paper quite often. We also sensitized our own plates and developed metal plates (which is insanely dangerous).