Usually i make the auto calibration, and everytime i change the shutterspeed or framerate, the camera make the auto calibration itself very quickly. But if i use a manual calibration (i stored a lot of different settings into the camera), and i change the shutter speed, the camera don't make the auto calibration itself, so i have to make it manually.

What's your favourite workflow? Another question: why RED choosed shutter speed and not shutter angle for the blackshading?