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Archive 2013 · ?? about flip down wide flash adaptor on speedlight
  
 
egd5
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p.1 #1 · p.1 #1 · ?? about flip down wide flash adaptor on speedlight


I have two questions about using this shooting into an umbrella to bounce back out.
1. Does putting this adapter down cause any light loss or is it (as I think) just totally a redistribution of the light?
2. Wouldn't it give more fill into the umbrella and therefore utilize more of the umbrellas spread to use this adapter? Especially so using a large (60-72") umbrella and two or more lights together.
Thanks



May 03, 2013 at 02:29 PM
cgardner
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p.1 #2 · p.1 #2 · ?? about flip down wide flash adaptor on speedlight


1. Very little light energy is "lost" when the WA lens is used. The same number of photons just illuminate a larger foot print; 14mm lens vs 24 mm for a 580ex flash.

2. When illuminating an umbrella with a speedlight the flash footprint should match the diameter of the umbrella filling it completely. If a 60" umbrella is used but the flash only lights a 30" circle in the middle it will function similar to a 30" umbrella.

The total power drop of umbrella vs. direct flash will be the difference in size of the footprint, minus whatever light is absorbed by the umbrella fabric, or if white projects out the back side. Usually it's in the range of -2 to -3 f/stops when measured with an incident meter.

Another problem with huge umbrellas in small rooms indoors is the footprint overlaps the ceiling and walls creating almost as much omni-directional "spill fill". That is OK if trying to light the room like and overcast day with low contrast lighting, but the lighting ratio can't be controlled that way.

A strategy which allows better control is to start with a foundation of centered fill creating few shadow the camera sees, with key lights which have a foot print large enough to cover the subject(s) evenly, but not so big the footprint bounces off walls and ceilings.



May 03, 2013 at 11:24 PM
RustyBug
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p.1 #3 · p.1 #3 · ?? about flip down wide flash adaptor on speedlight


The amount of light coming out of the flash remains the same .... the distribution and corresponding angles/distances of where you are bouncing your photons will be the variable. How thinly you spread your photons will be dependent upon the area of coverage you are distributing across.

Consider a "pat" of butter spread across a cracker vs. a piece of bread. The cracker will have a "richer" taste to it as the butter is more concentrated to a localized area, while the thinner spread of butter across the bread will have a "thinner" flavoring to it.

Now, use TWO pats of butter to spread across your bread and you can achieve a "richer" flavoring than that of just one pat ... but TWO pats onto a cracker might be a bit too "tasty" for some palletes.

It is essentially an issue of output volume (one pat or two) vs. area of distribution (cracker or bread) to achieve a concentration level at the subject (rich/contrasty or thin/flat). How "tasty" you want your subject to be is up to you. Are you spreading all of your light onto your subject, or is some of it being slathered wastefully (as in a spill) onto the counter (around the room).

Some of the realized light loss is due to the absorption of energy by the fabric, but much of the variance at how much energy is reaching your subject (and reflecting to the camera) is due to how "thin" you are spreading your light (redistribution angles/distance) ... and of course, what angles are involved for shadow placement.

BTW, props to whoever first told me @ butter years ago.



May 04, 2013 at 12:28 PM
 

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egd5
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p.1 #4 · p.1 #4 · ?? about flip down wide flash adaptor on speedlight


Thanks guys, very good info from both of you. I was thinking along those lines anyway, but wasn't sure.


May 04, 2013 at 02:36 PM
BrianO
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p.1 #5 · p.1 #5 · ?? about flip down wide flash adaptor on speedlight


egd5 wrote:
I have two questions about using this shooting into an umbrella to bounce back out.
1. Does putting this adapter down cause any light loss or is it (as I think) just totally a redistribution of the light?
2. Wouldn't it give more fill into the umbrella and therefore utilize more of the umbrellas spread to use this adapter? Especially so using a large (60-72") umbrella and two or more lights together.


As said above, wider spread doesn't mean ligh loss, just a different distribution.

That said, it may be better to fill the entire surface by moving the flash back from the umbrella rather than increasing the angular spread coming from the flash.

The reason for this is that angle of incidence equals angle of reflection. If the light hits the umbrella at more of an angle it will bounce out at more of an angle, and so you may be sending light off where it won't do any good in lighting the subject. If that happens you're just wasting light/batteries.



May 04, 2013 at 03:10 PM
egd5
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p.1 #6 · p.1 #6 · ?? about flip down wide flash adaptor on speedlight


Another good point. The level of knowledge here surpasses any college.


May 04, 2013 at 11:30 PM





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