The relationship between light quality and Fall-off (2 replies and 2 comments)
Excuse me, I'm a little confused about the connection between light quality and falloff
Theoretical books say that when the drop of light is fast, the quality is hard. But in this scene, for example, the quality of light, according to the DP, is soft, but Falloff is fast (part of the face is in complete darkness)
sorry, my questions may be obvious, but the fact is that I am writing my dissertation and this issue has occupied my mind. Thanks
The inverse square law applies whether the light is bouncing off a wall or being projected through a lens. The 'fall-off' of light doesn't vary relative to a source but it will vary between sources that are at varying distances from an object. The fact that the character's face is dark on one side is purely a consequence of the position of the source and it's size, rather than anything to do with 'fall-off'.
Thank you very much for your explanation dear sir deakins. You are really generous in teaching us, Master
Fall-off rate and light quality/texture (hard, soft, and in-between) are separate issues though they have practical interactions. Fall-off rate is mainly a function of distance from source to subject; hard or soft is mainly a function of the size of the source relative to the subject (and by size I don't mean wattage.) So you can have a soft or hard source with a fast or slow fall-out rate.
An overcast sky is a very large, soft source with a very slow fall-off rate and a candle flame close to a face is a fairly hard source with a fast fall-off rate. The sun on a clear day is a relatively small and hard source with a slow fall-off rate and a 4x4 fluorescent light box a foot from a face is a soft source with a fast fall-off rate.
Thank you very much for your comprehensive answer, dear master.