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Cameron Dozier

Difference between Undercranking and Simulating in Post

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Some of my DP friends swear that shooting 24p, then speeding up in After Effects by dropping frames to simulate an undercrank, is just as good as undercranking in camera.


Others say they can tell if it was done in post.


Won't After Effects produce a different result if you try to simulate an undercrank of 12fps, than if you actually just undercrank 12fps?


Or will they look exactly the same?

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Footage shot at 12fps will have twice the motion blur of footage shot at 24fps. That additional motion blur may well be very noticeable depending on the material.

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With a 180 degree shutter, the exposure time per frame is 1/48th at 24 fps and 1/24th at 12 fps, so as Stuart says, if you just drop every other frame or play back at 2X, you still have the blur from 1/48th instead of 1/24th unless you also apply some post process to increase blur, which is possible -- you could blend every two frames into one for example, or increase Digital Noise Reduction to the point that the motion smears more.


Or you could shoot at 24 fps with a 360 degree shutter (shutter off) on a digital camera to get a 1/24th shutter time but then you are sort of stuck with that look at 24 fps until you convert it to 12 fps.

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