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Greenscreen and using filters


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#1 Brian Dzyak

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Posted 15 September 2006 - 11:05 PM

In my experience when working with other DPs and shooting greenscreen on my own, I've "learned" that you should never use any kind of diffusion filter in front of the lens so that post has the cleanest edge possible with which to cut a key.

A couple of years ago, a producer asked me to use a diffusion filter on a greenscreen...I did...and post had a fit claiming that I "ruined" the shoot. I think they were able to cut the key, but it just wasn't as clean as possible.

So today, I got a call to do a greenscreen shoot this coming Monday, and almost as an aside, the young Producer said that I'd need to drop in a 1 SFX or a 2 SFX. My Spidey-sense went bonkers so I advised him against it, particularly because he would be using the exact same post department that complained so vehemently before. He claimed that they had just completed another round of shoots on greenscreen using a SFX with "no complaints."

I'm going to talk to the post dept myself before dropping any glass in, but I was wondering what everyone else's experience and/or opinions are about this. Logic says that you'd want to keep the image as clean as possible and add any diffusion effects later on, but if I'm asked to drop in some glass, how much should I protest?
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#2 Will Earl

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Posted 16 September 2006 - 04:36 AM

If there is something opticially that you're getting out of the use of a filter (and being captured on camera) that you couldn't easily replicate digitally in post then I could see a reason for shooting with the use of a filter (and just putting up with the complaints for Post).

Otherwise, it seems more reasonable to shoot neutral and then apply the effect in the DI process.

Talk to the Post House yourself, they may have come up with a solution for dealing with such cases.
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#3 Stephen Williams

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Posted 16 September 2006 - 04:56 AM

In my experience when working with other DPs and shooting greenscreen on my own, I've "learned" that you should never use any kind of diffusion filter in front of the lens so that post has the cleanest edge possible with which to cut a key.

A couple of years ago, a producer asked me to use a diffusion filter on a greenscreen...I did...and post had a fit claiming that I "ruined" the shoot. I think they were able to cut the key, but it just wasn't as clean as possible.

So today, I got a call to do a greenscreen shoot this coming Monday, and almost as an aside, the young Producer said that I'd need to drop in a 1 SFX or a 2 SFX. My Spidey-sense went bonkers so I advised him against it, particularly because he would be using the exact same post department that complained so vehemently before. He claimed that they had just completed another round of shoots on greenscreen using a SFX with "no complaints."

I'm going to talk to the post dept myself before dropping any glass in, but I was wondering what everyone else's experience and/or opinions are about this. Logic says that you'd want to keep the image as clean as possible and add any diffusion effects later on, but if I'm asked to drop in some glass, how much should I protest?


Hi,

If you want a perfect composite DON'T ever use any diffusion filter whatsoever! The filter will cause the blue/green to bleed over the edges. You will loose all hairs etc. so the composite will look cut out.

Try a test for the post dept shooting water and smoke on a blue/green screen, both with and without a diffusion filter. I think they will come to the same conclusion!

Stephen
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#4 Stephen Williams

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Posted 16 September 2006 - 04:58 AM

In my experience when working with other DPs and shooting greenscreen on my own, I've "learned" that you should never use any kind of diffusion filter in front of the lens so that post has the cleanest edge possible with which to cut a key.

A couple of years ago, a producer asked me to use a diffusion filter on a greenscreen...I did...and post had a fit claiming that I "ruined" the shoot. I think they were able to cut the key, but it just wasn't as clean as possible.

So today, I got a call to do a greenscreen shoot this coming Monday, and almost as an aside, the young Producer said that I'd need to drop in a 1 SFX or a 2 SFX. My Spidey-sense went bonkers so I advised him against it, particularly because he would be using the exact same post department that complained so vehemently before. He claimed that they had just completed another round of shoots on greenscreen using a SFX with "no complaints."

I'm going to talk to the post dept myself before dropping any glass in, but I was wondering what everyone else's experience and/or opinions are about this. Logic says that you'd want to keep the image as clean as possible and add any diffusion effects later on, but if I'm asked to drop in some glass, how much should I protest?


Hi,

If you want a perfect composite DON'T ever use any diffusion filter whatsoever! The filter will cause the blue/green to bleed over the edges. You will loose all hairs etc. so the composite will look cut out.

Try a test for the post dept shooting water and smoke on a blue/green screen, both with and without a diffusion filter. I think they will come to the same conclusion!

Stephen
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#5 Mike Brennan

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Posted 18 September 2006 - 10:50 AM

Hi,

If you want a perfect composite DON'T ever use any diffusion filter whatsoever! The filter will cause the blue/green to bleed over the edges. You will loose all hairs etc. so the composite will look cut out.

Try a test for the post dept shooting water and smoke on a blue/green screen, both with and without a diffusion filter. I think they will come to the same conclusion!

Stephen


Here here.

You could be very trixy and apply localised diffusion in lets say a medium closeup as long as the diffusion did not interfere with the edges but subject would have to ramin fairly still...


Mike Brennan
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Gamma Ray Digital Inc

Paralinx LLC

Willys Widgets

Visual Products

Tai Audio

rebotnix Technologies

Rig Wheels Passport

Glidecam

Media Blackout - Custom Cables and AKS

Aerial Filmworks