In porn to hit marks if your shooting semi gonzo style is hard. In manistream, everything is story boarded out, They have doubles come in, the same body type of the stars. Block it all out,measure it and the marks are set. So when Tom Cruise comes in,he knows this is the mark he has to hit in the scene. Plus they get coverage.Which means they shoot the whole scene with a long shot,then do it from actor a's pov then actor b's pov. Running the whole scene each time. Imagine shooting a scene where you have to break down and then have to do it over and over. That's why it takes months to shoot a 90 minute film.
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