Size vs Distance Pt.2

There are essentially two types of modifiers in terms of the light falling on the subject. There are restrictors, such as reflectors, barn doors, snoots, flags, grids, etc. And there are diffusers. Many think of them in similar terms, as controlling the size/area of light. But they do entirely different things.
 
A restrictor only modifies size/area of coverage... and as such the light from it is from a single source, the light rays falling on the subject are nearly parallel and are always "hard."
 
A diffuser, on the other hand, also breaks the light up into a huge number of light sources. Every point on the surface is a separate light source with a separate "fan of light." It's these separate fans of light that provide "wrap" and make the light from a diffuser "soft" when used close.
But when used from longer distances the only light falling on the subject is the rays that are nearly parallel and the light looses it's wrap and softness... it becomes "hard" again. Once the light falling on the subject is only the parallel rays you cannot make it harder by moving it father away. You can only affect the relative strength/power.
 
This is why the distance of the modifier, relative to the size of the modifier and size of subject is critical.

 
 
Reflective umbrellas are really more of a restrictive type of modifier. However, due to the way they are mounted and the angles involved they have an increased ability to create "wrap." But if used from too great a distance, they also become "hard" light sources as well.


 
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