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#1 Hashem Darzi

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Posted 19 April 2014 - 03:56 PM

hello friends . i want to learn what relation is between ، distance of light whit object


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#2 David Mullen ASC

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Posted 19 April 2014 - 04:37 PM

The question is confusing, could you be more specific?


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#3 Hashem Darzi

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Posted 19 April 2014 - 10:20 PM

severity of the light how much is step down when object is receding .     how much is low, serverity of light.


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#4 Hashem Darzi

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Posted 19 April 2014 - 10:49 PM

severity of the light how much is step down when object is receding .     how much is low, serverity of light.

 

 

The question is confusing, could you be more specific?

severity of the light how much is step down when object is receding . how much is low, serverity of light.


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#5 David Mullen ASC

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Posted 19 April 2014 - 11:27 PM

What do you mean by "severity" -- the sharpness or the brightness?  What do you mean by "step down"?  Are you asking how quickly the light level falls off with distance?  For point sources, you can generally apply the inverse square law:

 

http://en.wikipedia....erse-square_law

 

The looser term is "fall off" and generally light falls off in intensity more rapidly when you are close to the source, more gradually when the light source is at a distance.

 

Movie lamp manufacturers often list photometric data in terms of foot-candles for their units.

 

As far as softness, how soft a light is depends on its size as a source relative to the subject.


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#6 Hashem Darzi

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Posted 21 April 2014 - 04:40 AM

 Hi Mr. David Thank you so much for helping me I've studied the inverse square law. I searched the Internet and Persian languages​​. I found my answer Now I think in scene that the actor has moved. Is better, the distance between the lights, with subject be more

thankful again for your help and your magnanimity


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#7 Hashem Darzi

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Posted 01 May 2014 - 05:20 AM

1-lenzak-a.jpg  hello friends i want to ask is there any way to have flat lighting in all of location, in this pictuer , from point of 1 until point 10

the mining  want to havefrom point 1 to 10 same apertur for example f 4 with one light


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#8 Will Barber

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Posted 01 May 2014 - 10:03 AM

Put the light on the side, so that the distance to the subject is always close to the same.


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#9 John Holland

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Posted 01 May 2014 - 12:18 PM

Your answer is more confusing than the question!
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#10 Hashem Darzi

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Posted 01 May 2014 - 12:58 PM

Your answer is more confusing than the question!

how can we have in all of this picture (point of 0 to point 10) enbloc level of aperture with one light


Edited by Hashem Darzi, 01 May 2014 - 01:02 PM.

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#11 Hashem Darzi

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Posted 01 May 2014 - 12:59 PM

how can we have in all of this picture (point of 0 to point 10) enbloc level of aperture with one light


Edited by Hashem Darzi, 01 May 2014 - 01:02 PM.

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#12 Alexandre de Tolan

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Posted 01 May 2014 - 01:34 PM

You are probably talking about fall off. If I understood your question right you want to have the same f-stop number (you mention f/4), from one point (1 in your diagram), to another (10).

 

Well, the only way to do this with only one fixture is to have a large one (Arrimax M40 for instance), the further away from your action that still gives you your intended f-stop number to your ISO setting.

 

That way the inverse square law will make its magic and fall off will be much less from point 1 to 10 than using a smaller fixture closer to your subject.

 

Of course that you will experience fall off anyway so you have to control it. The easier way is to strategically place the right amount of nets (single or double), to control that fall off within certain limits of your action.

 

Use your incident light meter to obtain the right amount of light you have to flag (net), closer to your fixture.

 

Hope this helps


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#13 Guy Holt

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Posted 01 May 2014 - 07:48 PM

... you want to have the same f-stop number (you mention f/4), from one point (1 in your diagram), to another (10).

 

Fresnel instruments spaced evenly apart and  set at full flood will create a consistent wash of light over a large area.  If  the edge of the beam of each light (the 50% drop-off point) is overlapped slightly so that it feathers into that of the next the overlapping beams  will create an even 100% intensity seamlessly across  a large area. 

 

Well, the only way to do this with only one fixture is to have a large one (Arrimax M40 for instance), the further away from your action that still gives you your intended f-stop number to your ISO setting.

 

Not true, the other way to do it with just one light is to use a combination of wire scrims and nets to grade the output so that it is even as talent walks towards the light. It helps to have the light at a steep angle.

 

Guy Holt, Gaffer, ScreenLight & Grip, Lighting Sales & Rentals in Boston


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#14 Alexandre de Tolan

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Posted 02 May 2014 - 06:02 AM

 

 

Fresnel instruments spaced evenly apart and  set at full flood will create a consistent wash of light over a large area.  If  the edge of the beam of each light (the 50% drop-off point) is overlapped slightly so that it feathers into that of the next the overlapping beams  will create an even 100% intensity seamlessly across  a large area. 

 

 

 

Guy, if you read the OP's posts the goal was to use one single light.

 

Not true, the other way to do it with just one light is to use a combination of wire scrims and nets to grade the output so that it is even as talent walks towards the light. It helps to have the light at a steep angle.

 

Guy Holt, Gaffer, ScreenLight & Grip, Lighting Sales & Rentals in Boston

 

 

Sorry but I still stand correct since the remaining of my answer (which you didn't quote), relates exactly to what you're saying above. Sorry if I just didn't wrote it on one sentence but for me the paragraph you quoted doesn't make sense without the other

 

I'm not an English native speaker so I just suppose I didn't expressed me sufficiently well but what you're saying is exactly what I was trying to say and if you read my previous post again you will verify just that.


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