Soft Filters with Green or Blue Screen

[Eric Ulbrich]

Curious to know if anyone here has ever shot any blue or green screen with effects filters on the camera.

Im thinking either black pro mists or classic soft filters. The film Im prepping for has a certain child-like wonder quality to it and I feel that some sort of softening filters might help to pop the highlights of the camera and give a more dream-like feel to it.

This is where I get worried:
The film is very heavy on the effects side. Lots of digital mapping, 3-D modeling and an insane blue screen (think 5 30x30 rags) Im worried that changing the sharpness and inherent image quality of the RED will drive the post people out of their minds. I also dont want to mess up the key on our chroma either.

So Im putting the image at all of your experience and mercy. Can you suggest any advice or other types of filters I havent mentioned? Any thoughts would help!

Thanks everyone!

 

[Pietro Impagliazzo]

Won't the diffusion blur and blend the edges of background and subject?

That's not very nice for keying. Diffuse on post.

 

[Joel Kaye]

So Im putting the image at all of your experience and mercy. Can you suggest any advice or other types of filters I havent mentioned? Any thoughts would help!

I've done enough greenscreen to be dangerous - but I have trained with some pretty experienced people and the advice I've gotten is capture a clean image.

RED is great because of the resolution and codec, but if you're shooting f2 and throwing all your markers out of focus you're making the 3D tracking harder... it might not be the best camera for a lot of tracking. Or you shoot wider lenses and higher apertures (tough to light a GS up evenly at higher apertures.

Needless to say a soft focus filter is probably one of the worst things you could add to that mix.

Absolutely get together with your VFX Director (or artist) in advance and design tests. Anyone can be the talent. Robert Rodriguez did just that with Sin City using himself as an actor. Once he knew he could get what he wanted only then did he proceed. That's my best advice for you.

 

[Shane Kelly]

stay clean. Get the sharpest lenses you can afford. Your compositor will thank you for it.

 

[Nick Gardner]

Short answer - contact the guy doing the post and ask him what he can live with. Done and done.

Cheers,

Nick

 

[Gavin Greenwalt]

It's always easier to apply effects to a clean plate. Especially if you're working in a lot of CG applying the pro-mist as a digital effect means every part of the shot is guaranteed to blend.

If your greenscreen is lit properly and you throw on some pro-mist then you'll get bloom from your screen in places where it wouldn't be appropriate. Maybe your actor is standing in front of a CG window. If the window is only on the left side of the actor you'll only want that nice glow on the left but not on the right. If you shoot with diffusion on the green screen then both sides of the actor will flare out from the green screen. You'll also probably muddy a lot of the skin tones with a bit of green diffusion.

Exception would be a scenario where maybe just the window is a green screen--an easier case could be made for going through the hassle of matching the diffusion for one small element.

But like all things: test, test and test some more. The above is just my gut reaction. But softening filters are by far one of the easiest and least demanding effects to simulate. I don't know that any added effort to deal with it in post would be worth any possible gains from doing it optically. The real pluses I can think of using an optical filter is in overbrights but that seems less likely to happen in a green screen scenario.

EDIT: Just a word of warning. Be wary of getting sucked in by all the talk of not shooting clean plates anymore. It's all the rage to just shoot with little to no concern for VFX and let it all get sorted out in post. You can do that when you have ILM's paint and roto department to meticulously isolate lens flares and other 'organic' bits in frame but most productions don't have the time or budget.