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Online Cinematography Exposure Calculator that works like my cinematography light meter?


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#1 John Robinson

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Posted 13 November 2015 - 05:00 AM

Does anyone know where I can find one?  Say I want to shoot at 400 ASA at f2.8, 180º and I want to calculate how many footcandles I'll need to get exposure.  I've tried a bunch of these online calculators but none of them are as fast as just picking up my Sekonic and moving it toward a light source until I get the desired t-stop and checking how many foot candles.  Any leads?


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#2 Kenny N Suleimanagich

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Posted 13 November 2015 - 11:10 AM

This is a helpful chart.


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#3 John E Clark

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Posted 13 November 2015 - 12:27 PM

Does anyone know where I can find one?  Say I want to shoot at 400 ASA at f2.8, 180º and I want to calculate how many footcandles I'll need to get exposure.  I've tried a bunch of these online calculators but none of them are as fast as just picking up my Sekonic and moving it toward a light source until I get the desired t-stop and checking how many foot candles.  Any leads?

 

The basic cinematography formula is @ ISO 100, @ f/2.8 @ 24 fps, you need 100 fc.

 

For ISO 400, that is 2 stops 'faster', so one needs 1/4 the fc... or 25 fc.

 

As for on set measurement... if one is using standard ligthts such as ARRI there's an iPhone (perhaps android as well...) app from ARRI which gives their lights and the photometric data you would need to know to set the light at a given distance, and get close to the desired illumination.

 

For cheap imports... anything goes... because for the most part if they mention anything it is just the wattage, and not information such as beam width, fc at various distances, etc... for those one has to measure and adjust as needed...

 

I do recommend the iPhone app pCam which has a number of calculation widgets that makes things a lot easier.


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