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High Speed Film Light Reading issue


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#1 Jonathan Taee

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Posted 18 February 2008 - 09:21 PM

I have a Photec IV high speed 16mm camera and want to shoot at 2000fps. I don't have a light meter that can measure the light needed for that frame rate. How should I go about measuring the light for such a high frame rate?

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#2 Robert Houllahan

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Posted 18 February 2008 - 10:30 PM

I have a Photec IV high speed 16mm camera and want to shoot at 2000fps. I don't have a light meter that can measure the light needed for that frame rate. How should I go about measuring the light for such a high frame rate?

Jonathan Taee



Is this a rotary prism camera? like a hycam? you need to find the shutter i.e. a 180 degree shutter will be 1/4000th of a second and the minimum optical stop, i.e. my HycamII's are a minimum of t4 then you need to find the exposure for the stock you are using how many foot-candles needed for the time and film ISO

An example we recently did a 500fps shot on a 4 sq foot area with a Locam and a pair of 2K tungsten lights which measured at 1800fc and I had a load of Tri-x that I rated at 140iso as I cross processed as negative. I exposed at a 2.8/4 split and the shot came out great.

On another setup there were 450 1k lowels and 500t at 8000fps exposed at a t4 I think there was around 4000fc on the subject.


The key with any hi speed photography is dump as much light as you can afford onto just the area you are trying to photograph, open face tungstens work best so 4 or 5 or 6 or 400 :blink: lowell 1K totas or omnis as close as you can get them to the subject.

-Rob-
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#3 Nick Mulder

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Posted 19 February 2008 - 02:49 AM

How should I go about measuring the light for such a high frame rate?



extrapolate
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#4 Robert Houllahan

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Posted 19 February 2008 - 02:56 AM

extrapolate



You could use a regular sekonic L398 with the high slide.....

-Rob-
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#5 David Auner aac

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Posted 19 February 2008 - 05:42 AM

On another setup there were 450 1k lowels and 500t at 8000fps exposed at a t4 I think there was around 4000fc on the subject.


Hi Rob, am I reading this correctly? 450 as in four hundred and fifty Lowel 1ks? Why not use a smaller number of 5ks or even bigger tungstens?

Cheers, Dave
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#6 Robert Houllahan

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Posted 19 February 2008 - 10:26 AM

Hi Rob, am I reading this correctly? 450 as in four hundred and fifty Lowel 1ks? Why not use a smaller number of 5ks or even bigger tungstens?

Cheers, Dave



Heh heh... can't say exactly but the 1k's were cheap in case they broke, they are easy to place around a large object and most 5k's are fresnels which don't work as well as open face reflectors...all other lights were tested...

-Rob-
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