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Pulling good Chroma key with Pro 35 apapter?


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#1 Frank Barrera

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Posted 06 December 2006 - 03:49 PM

Has anyone ever pulled a Chroma Key from video material shot with a Pro 35 adapter? I am wondering specifically about the Digi Beta format but I suppose HD would be informative as well. The question specifically is: Does the softening effect of the adapter cause problems for pulling a good key?

Thanks

f
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#2 David Cox

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Posted 10 December 2006 - 12:40 PM

Has anyone ever pulled a Chroma Key from video material shot with a Pro 35 adapter? I am wondering specifically about the Digi Beta format but I suppose HD would be informative as well. The question specifically is: Does the softening effect of the adapter cause problems for pulling a good key?

Thanks

f


No - I've seen no additional problems caused by the use of a pro-35 adapter.

David Cox
Baraka Post Production
www.baraka.co.uk
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#3 David Mullen ASC

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Posted 10 December 2006 - 01:14 PM

The question is why keep the adaptor on at that point? You're using it just to reduce depth of field, but in a chromakey shot you don't want the focus to be too shallow, so just remove the adaptor and switch to a decent B4 video lens for that stuff.
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#4 Frank Barrera

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Posted 10 December 2006 - 09:33 PM

The question is why keep the adaptor on at that point? You're using it just to reduce depth of field, but in a chromakey shot you don't want the focus to be too shallow, so just remove the adaptor and switch to a decent B4 video lens for that stuff.


Yes, I agree and have argued as much with the director. His retort is that he wants the "grain". My response to that is that since we are doing a heavy effects post path anyway he can just add some grain in later. In the end the post supervisor stepped in and declared that he wants the "cleanest" image possible. So, no adapter.


Thanks
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#5 David Cox

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Posted 12 December 2006 - 03:42 AM

Yes, I agree and have argued as much with the director. His retort is that he wants the "grain". My response to that is that since we are doing a heavy effects post path anyway he can just add some grain in later. In the end the post supervisor stepped in and declared that he wants the "cleanest" image possible. So, no adapter.
Thanks
F


Although the adapter would loose some light, as long as this was compensated for with extra light rather than camera gain, it shouldn't have to lead to extra grain. However, grain is a killer for good blue screens.

If your blue screen subjects are on a single plane, then there is no reason to use the adapter anyway - as David M suggested.

However, if your blue screen subjects are deep enough to show a depth of field of their own, then you ought to use the adapter other wise all your blue screen objects will be sharp and that might look at odds with your background and the rest of your film. For any blue screen that has either out-of-focus or motion blurred foreground elements, it is very important to ensure the blue screen is flatly lit to get a single blue colour across the entire screen - minimal shadows, folds and light fall off.

Good luck with your shoot.

David Cox
Baraka Post Production
www.baraka.co.uk
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#6 Frank Barrera

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Posted 12 December 2006 - 05:51 AM

Although the adapter would loose some light, as long as this was compensated for with extra light rather than camera gain, it shouldn't have to lead to extra grain. However, grain is a killer for good blue screens.


I am refering to the "grain" that you get from ye old spinning mirror. Not that which would result from using the gain on the camera. The idea is that the back plate material would have the apparent grain so the director wanted the green screen to have it as well. That was the original question: Does the grain form the mirror result in keying problems?

As I stated above we are just tossing the whole adaptor out the window anyway. Now the issue is we are supposed to shoot ext back plates tomorrow and the forcast calls for snow. ugh.

f
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