Quote Originally Posted by cmacd123 View Post
Just to allow for the fact that more modern films shrink less than the nitrate ones did, it was found useful to space the Negative perfs a bit (4 ten thousands) closer than the positive perfs to avoid slippage in the printer. so you generaly find Movie negative with a "BH-1866" perf while positive print film is supplied as KS-1870, as is most film inteded for still camera use.
Any change in degree of shrinkage affects both, the negative and the print film. The idea of using a larger hole distance on print film is due to films whilst copying running over a drum as sandwhich with the print film being the outer one.