Film weave is also the bane of the VFX world. If a shot is going to have, say, a matte painting added in post, then a pin registered camera must be used. These cameras have a precisely machined pin that centers the film stock in the gate after the pull down claw retracts. Later post processing stages also use pin registered movements, so each frame is in exactly the same place every time it's used. Otherwise, the separate elements would weave against each other and give away the effect.