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What to do about changing light?


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#1 Nick Castronuova

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Posted 11 February 2008 - 03:33 AM

Sorry guys, I know I ask some basic questions but here's another:

How do you compensate for the changing f-stops when filming outdoors? Let's say that I am filming all day, and the F-stop changes from an f/11 to an f/8, do I just open up one stop?

Thanks!

Nick
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#2 Kevin Zanit

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Posted 11 February 2008 - 03:44 AM

Well you would certainly want to maintain correct exposure, not underexpose something you are trying to match. I normally use ND when shooting outside, so I would pull ND from the lens rather then change the stop to maintain consistency in DOF.

Now all this does not help match the changing light over the day. I usually try to shoot the wide shots together and then the closer coverage because its easier to match the lighting in closer shots.

Sometimes you just have to use "brute force" to make things match:
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#3 timHealy

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Posted 11 February 2008 - 07:56 AM

those aren't "brutes" ... hhehhehe

best

Tim
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#4 chris marte

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Posted 11 February 2008 - 11:50 PM

Sorry guys, I know I ask some basic questions but here's another:

How do you compensate for the changing f-stops when filming outdoors? Let's say that I am filming all day, and the F-stop changes from an f/11 to an f/8, do I just open up one stop?

Thanks!

Nick
[/quote]


As long as the amount of light falling on the subject you're filming stays the same, there generally shouldn't be a reason for you to have lower f stop readings. Use a lighting setup that compensates the amount of light you've lost since the last scene you shot.
For example, let's say a reading of f/ 11 gives you the equivalent of 800 footcandles (FC) of light. Since every subsequent stop going down (f/11, f/8, f 5.6, etc.,) lets in half as much light as the previous, f/ 8 would in that case give you the equivalent of 400 FC. To make up the 400 footcandles of light lost, there's some helpful mathematical calculations available on photography websites, or you can just play with your lights until your meter reads as it did before.
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#5 chris marte

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Posted 11 February 2008 - 11:50 PM

As long as the amount of light falling on the subject you're filming stays the same, there generally shouldn't be a reason for you to have lower f stop readings. Use a lighting setup that compensates the amount of light you've lost since the last scene you shot.
For example, let's say a reading of f/ 11 gives you the equivalent of 800 footcandles (FC) of light. Since every subsequent stop going down (f/11, f/8, f 5.6, etc.,) lets in half as much light as the previous, f/ 8 would in that case give you the equivalent of 400 FC. To make up the 400 footcandles of light lost, there's some helpful mathematical calculations available on photography websites, or you can just play with your lights until your meter reads as it did before.
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#6 Kevin Zanit

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Posted 12 February 2008 - 02:53 AM

those aren't "brutes" ... hhehhehe

best

Tim


Haha, Zing . . .
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The Slider

Paralinx LLC

Visual Products

Aerial Filmworks

Willys Widgets

Opal

Glidecam

CineLab

Wooden Camera

Broadcast Solutions Inc

CineTape

Gamma Ray Digital Inc

Media Blackout - Custom Cables and AKS

Tai Audio

Metropolis Post

Rig Wheels Passport

FJS International, LLC

Abel Cine

Ritter Battery