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Re: Diffusion Scrim question: Two 4x4s or one 42x72?

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Bill Davis
Re: Diffusion Scrim question: Two 4x4s or one 42x72?
on Mar 31, 2018 at 9:08:36 pm
Last Edited By Bill Davis on Apr 1, 2018 at 4:51:01 pm

Think of it this way.

No matter the size or shape of the diffusion your goal is lighting an object (say a 6' tall person) from head to toe.

Say you only have ONE light. If you position that light in the middle, the strongest photons are coming from the brightest middle area of the diffusion and spreading up and down onto the subject. If you move that light UP to the top of the diffusion, the strongest photons come at the subject from higher up - (and as critically, there is now much more distance that those photons have to travel to reach the model's feet. So the inverse square principle tells you that his or her feet, will have a lower illumination level than their hair.

See how it works? The position of the illuminating instrument STILL effects which parts of the subject gets the most light even with diffusion in between. The key is the distance the photons have to travel since the inverse square principal dictates that they lose a lot of their energy over distance.

If you want to control the apparent brightness of areas of the subject, just adjust the position of the light sources relative to the subject.

If you want a brighter top, then light up the top of the diffusion with one light, and fill the middle and lower zones with the second source.

Hope that helps.

Creator of XinTwo -
The shortest path to FCP X mastery.

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