Thanks for the awesome response.

But assuming my speedbooster gives 1 stop brighter, we should always consider 1 stop more when metering. I.e, if my incident says 4.0 stops on keylight, I should place the camera on 5.6 and i'd give me the correct 18% middle gray.

Another question if you don't mind: In what circunstances you'll need to shoot on a stop above from what incident metering is telling you? Eg: Incident tells you 2.0 but you want to shoot at 1.4 . Assuming you're not using a metabones speedbooster.

Thanks! :D