Sprocket holes
"Whilst cinema film must have sprocket holes, they are not necessary in still photography."
The problem with advancing film is that the obvious mechanism of winding it between two spools gives a non-linear travel - as the take-up spool diameter increases with used film.
The old roll film cameras required the user to watch carefully for a frame number to appear in a little window as they wound the film on.
Sprocket holes meant that the amount of film passing could be accurately measured by clicks as it passed over a toothed wheel with a ratchet. The camera would automatically stop the film when the next frame was aligned. It would also only cock the shutter when that point was reached. Deliberate multiple exposures were permitted by disengaging the film travel whilst still priming the shutter.
That reliable automatic registration mechanism also enabled bulk film magazines, motor drives, and remote/unattended operation.
How the large format professional cameras solved that automatic registration problem for roll films without slippage is probably more complex and expensive.
Biting the hand that feeds IT
