I have done limited video work, and nothing with human subjects that required much forethought on mood. I do, however, love learning about the behind-the-scenes of cinematic productions as it can be of use in stills photography too. In this video, Rob Ellis gives one of the clearest explanations I've seen on one particular lighting technique: contrast ratio.
As with many techniques in photography, precision is often neglected because eyeballing the result will get you close enough. However, if you want to create consistency in your work, utilizing a formula is the way to go, and it's easier than it sounds. In essence, the higher the ratio, the more contrast there is, and the more dramatic the mood.
Yes, for videography, the consistency this brings is essential to production value. However, for photography, this can improve your work too, particularly if you're creating a series. Understanding how to recreate the same contrast ratio across different scenes can be a powerful tool.
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