# Diffused Reflections



## joel28 (Dec 26, 2012)

I'm reading the book Light, Science & Magic, Chapter 3, and it states:

*"So we now have seen that neither the angle nor the size of the light source affects the appearance of a diffuse reflection. However, the distance from the light to the surface of the subject does matter. The closer the light gets to the subject, the brighter the subject becomes and, at a given exposure setting, the lighter the subject appears in the finished picture."*


When the light source is at an angle (for example 90 degree), isn't one part of the Diffused Reflection further away?


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## fjrabon (Dec 26, 2012)

joel28 said:


> I'm reading the book Light, Science & Magic, Chapter 3, and it states:
> 
> *"So we now have seen that neither the angle nor the size of the light source affects the appearance of a diffuse reflection. However, the distance from the light to the surface of the subject does matter. The closer the light gets to the subject, the brighter the subject becomes and, at a given exposure setting, the lighter the subject appears in the finished picture."*
> 
> ...



I suppose so, but unless it's overall extremely close, it's inconsequentially further away.  Also, what do you mean by 90 degrees?  Either that's dead straight on, or completely 100% side lit.


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## joel28 (Dec 26, 2012)

If the light source (soft box) is tilted, wouldn't part of it be further away of the subject?


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## fjrabon (Dec 26, 2012)

joel28 said:


> If the light source (soft box) is tilted, wouldn't part of it be further away of the subject?



Sure, but if it's more than 3 or so feet away, 1-2 inches won't make a huge deal.  

If the light is 3 feet away and tilted such that the far side is 3 inches further than the close side, the difference in illumination is roughly 1/10 a stop from the closer side to the further side.  Which is nearly impossible to see.  

It's a combination of the inverse square law, and calculating the spill from the closer side to areas that are mostly lit by the further side.  And this isn't even taking into account that a softbox is brighter in the middle than in the edges, and thus more light comes from one single point than either of the two edge points we are talking about.  If you do ALL the painstaking math, it could come out to be significantly less than 1/10 a stop.


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## cgipson1 (Dec 26, 2012)

Hey Joel, saw your facebook message on this! What fjrabon said above is correct.... you are over thinking it! Good book, huh?


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