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Diffusion Transmission with the Sun vs Lights


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#1 Ryan Emanuel

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Posted 16 April 2017 - 02:06 PM

I've noticed that the when I set diffusion frames to diffuse the sun, they take away way more light then when I put them in front of a light.  Is that because of an inverse square thing?


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#2 Stuart Brereton

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Posted 16 April 2017 - 02:31 PM

The transmission characteristics of diffusion materials are a constant. They don't change depending on the light being put through them. For instance, LEE 416 has a 50% transmission, so it loses 1 stop of light. This will be the same regardless of whether it is diffusing the sun or a lamp.


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#3 Mark Kenfield

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Posted 17 April 2017 - 08:06 AM

I think what you're seeing Ryan, is simply the same amount of diffusion, but the effect looking stronger, because outdoors is a much higher contrast environment than indoors - so when you diffuse the light hitting your subject, your background looks much brighter by comparison.
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#4 Satsuki Murashige

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Posted 17 April 2017 - 04:55 PM

Also, I suppose with an overhead frame you are also taking away some ambient skylight and increasing the relative amount of ambient bounce fill from below.

Outdoors at midday, there's literally bounce fill coming from everywhere, even if if our eyes can't normally see it since it's overpowered by direct sunlight. Take that direct source away and suddenly it's a lot more apparent. So you definitely feel the directional change of light more than if you were diffusing from the side.
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