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ISO for video camera!


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#1 Gabriel Rochette

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Posted 27 February 2007 - 01:05 PM

Goog way or not ?????
To find the ISO of a camera video: lighting a gray cart 18% with a spot 3200K
Frame the gray cart and put the iris in auto mode....
Look the result ex: f/2.8
Take a light mesure with a photometer (incident one)
Look the result... and shift the ISO dial until finding the f stop of the camera
Read the ISO value
I't is good and safe???
Thank you
Gabriel Rochette
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#2 Daniel Sheehy

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Posted 27 February 2007 - 03:08 PM

Hi,

As discussed here apparently 18% grey isn't the best way to go with the video cameras. Better to take a reading from an average scene (no excessive hightlights, no large black holes) and then match the ISO that way.
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#3 David Bradley

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Posted 27 February 2007 - 05:37 PM

Everytime I have tested a video camera's speed I have hit approximately 320 ISO. The sony f900 is at that speed, as is the 570ws, the 450ws and the dvw790. I used the method you have described above and I would say its the been the best way in my experience short of a waveform monitor.
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#4 Michael Nash

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Posted 27 February 2007 - 06:02 PM

"Beware the auto iris..."

The auto-iris on video cameras is quite often set too high, putting a gray card well above 50 IRE. You're better off using a waveform monitor to set the desired brightness, probably closer to 45-50 IRE depending on the look you want. Without a waveform monitor you can use a properly set up monitor and set a correct exposure by eye, cross referencing the gray card and other subjects until you come up with a sensitivity that's consistent.

But as already stated, the effective ISO of a camera can vary with the light level, and "proper" exposure may be determined by the highlights as much as the midtones. Use the effective ISO as a rough guide for lighting only; don't set your exposure by it.
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