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Charles DeRosa

Soft Light - Technique

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look, i don't know the exact math, but if you're doubling your distance from the center of a very large light source, you haven't doubled the distance to its edges. this must make for a slightly different equation, right?

 

/matt

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I f u move one meter away form the sun u are one f/stop down?

i wouldn't call billions of meters plus one the double of billions of meters though, not even if i choose to accept huge roundoff errors... ;-)

 

/matt

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Greg,

I am posting one page here for you that maybe help me get away from ''the lions mouth''. ''Even the sun?'' I f u move one meter away form the sun u are one f/stop down?

Dimitrios koukas

 

 

Sorry Dim,

That page has stuck your head into the mouth of the lion!. Look at the tables, All the quoted amounts hold true. Please remember what I said before:

 

* the one exception being collimated light of the type produced by lasers. Collimated light has light waves which are precisely parallel and do not spread out - and so such light does not follow the inverse square law.

 

Some of your lights are collomated sourses so the law does shift a litttle ( not significantly though) from the law.

 

 

Take an example light like this one in the diagram. By doubling the distance the light is a quater. Do this for any of the lights listed in your diagram, taking into account the collimated lights ALL these light hold true on the inverse law.

 

Tell me I didnt study 4 years of photometry for nothing? LOL

post-944-1127568302.jpg

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Sorry Dim,

That page has stuck your head into the mouth of the lion!. Look at the tables, All the quoted amounts hold true. Please remember what I said before:

 

* the one exception being collimated light of the type produced by lasers. Collimated light has light waves which are precisely parallel and do not spread out - and so such light does not follow the inverse square law.

 

Some of your lights are collomated sourses so the law does shift a litttle ( not significantly though) from the law.

Take an example light like this one in the diagram. By doubling the distance the light is a quater. Do this for any of the lights listed in your diagram, taking into account the collimated lights ALL these light hold true on the inverse law.

 

Tell me I didnt study 4 years of photometry for nothing? LOL

 

 

 

gET ME OUT!

 

:D :D

oOPS i HAVE TO GO BACK TO SCHOOL THEN. nO PROBLEM AT ALL.

 

 

Dimitrios Koukas

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Here's where I have seen confusion on this topic: Three factors are in play- ISL (inverse square law), deflection and recombination.

 

The uninterrupted transmission of light rays always loses energy by ISL. The diffuser deflects some of that energy away from the target. The larger "resourcing", if you will, (at the diffuser) of energy means that some of the deflection will recombine onto the target.

 

So, you get loss by ISL, loss by diffuser deflection, and gain by recombination.

 

This makes estimating of target values dang-near impossible due to variations in distance, source, "resourcing", size of beam at diffuser, diffusion material, and recombination.

 

Thank God for light meters.

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Sorry Dim,

That page has stuck your head into the mouth of the lion!. Look at the tables, All the quoted amounts hold true. Please remember what I said before:

 

* the one exception being collimated light of the type produced by lasers. Collimated light has light waves which are precisely parallel and do not spread out - and so such light does not follow the inverse square law.

 

Some of your lights are collomated sourses so the law does shift a litttle ( not significantly though) from the law.

Take an example light like this one in the diagram. By doubling the distance the light is a quater. Do this for any of the lights listed in your diagram, taking into account the collimated lights ALL these light hold true on the inverse law.

 

Tell me I didnt study 4 years of photometry for nothing? LOL

 

And know that I was keep wondering, and used your type too, look what I ve found.

Check this HMI in the flood position.Please any corrections will do just good to me, so correct me if I am wrong.

Dimitrios Koukas

 

post-8298-1129191096.jpg

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