advice needed for shooting green screen with AF100: FPS? ISO? F-stop?

N

Nicholas Natteau

Veteran
Just asking because I didn't find the answers in other posts.
I'm shooting talking head interviews with my AF100 using Reflecmedia's Litering and Chromaflex.

• FPS???
What's the best frame rate for shooting green screen? 24, 30, or 60 fps?
Will I get cleaner results shooting at 720p60 than at 1080p24?

• F-stop???
Not sure what F-stop I should be at, best one for green screen?
Should I have a very shallow depth of field or the opposite? Just asking because I hear that when using Reflecmedia it's not the same as working with traditional green screen.

• Lenses???
Best lenses for green screen shooting? Are primes better than zooms?
I have a Zeiss 85mm (f1.4), 50mm (f1.4), 35mm (f2.0) ZF primes and Canon 70-200mm f2.8 zoom, plus GH1 14-140mm f4.5 stock lens.

• ISO???
Should I be shooting at the lowest ISO speed possible?

• Best AF100 scene file settings???
Finally, for green screen, what AF100 settings should I tweak in the scene file menu section?
Is it true that Cine-V or Cine-D should be avoided when shooting in green screen?

Thanks in advance for any help.
 
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Hi Nic. I have shot greenscreen in camera in card, at 1080 60fps VFR 24P and it looked brilliant. At that rate I did have to come up in ISO to 640. The camera keys clean. I was in CineV gamma, cinelike matrix -2 master ped, -2 detail 0 everything else. looks fantastic as long as you light it the right way.
 
Hi Scott, thanks very much for your help. I very much appreciate it. Will try those settings. I'm sure other AF100 users will find it very helpful as well. Thanks!

You mentioned 1080 60fps for slow motion, correct? But if you had to choose between 1080p24 and 720p60, which frame rate would be better for green screen work? Or does it not matter? Again, this would only be for sit down interviews, no fast action.
 
i would shoot 1080 30P for starters. i like a decent stop like 4.0 so you have plenty of dof to cover random subject movement and you are also working in a sweeter range or your lens. unless you are using very HQ glass, I'm talking about zeiss cine glass or equivalent, give your lenses a chance to operate in their optimum zone, which is generally NOT wide open.

if you light the interview correctly, keep your subject a stop or so above BKG level and your background lighting is tight: flat waveform and narrow waveform for the background, your keying issues should be minimized.
 
Frame rate is all about what you want the motion to look like. If you want 24p motion, use 24p. If you want 30p motion, use 30p. If you want 60p motion, use 60p.

They all key just fine.
 
(agreed, except I would avoid 60i if at all possible... interlaced keying is not nearly as smooth and easy as progressive keying!)
 
Scott Wellington said:
Hi Nic. I have shot greenscreen in camera in card, at 1080 60fps VFR 24P and it looked brilliant. At that rate I did have to come up in ISO to 640. The camera keys clean. I was in CineV gamma, cinelike matrix -2 master ped, -2 detail 0 everything else. looks fantastic as long as you light it the right way.
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The OP is shooting interviews so I would not recommend a VFR. If he does so , he is in for a big shock!
 
I find dropping detail back a lot helps avoid fine lines around edges.I bring back the detail in post after the key with a little sharpening.This camera pulls a great key, but do a heap of test shots and take them right through post to find your optimum workflow.Agree that shallow DOF is the last thing you need when shooting interviews.And keep plenty of distance between subject and the screen.Good luckTex.
 
Shallow dof can really destroy a green screen shot. If you are not careful. I tool like p cam or any other calculator for establishing your splits at a given stop and focal length for dof is a really good thing to refer to when setting up some green screen.
 
Thanks everybody. Texwhitney, when you refer to dropping detail, which detail are you refer to in the AF100...Detail? or Vertical Detail? And if so how far would you drop either one? All the way?
 
texwhitney said:
I find dropping detail back a lot helps avoid fine lines around edges.I bring back the detail in post after the key with a little sharpening.This camera pulls a great key, but do a heap of test shots and take them right through post to find your optimum workflow.Agree that shallow DOF is the last thing you need when shooting interviews.And keep plenty of distance between subject and the screen.Good luckTex.
Click to expand...

Thanks everybody. Texwhitney, when you refer to dropping detail, which detail are you refer to in the AF100...Detail? or Vertical Detail? And if so how far would you drop either one? All the way?
 
I would drop them both pretty low -6 or -7(off) Then sharpen in post if you need to do. The camera produces a much more natural image with those settings as well.
 
As Logan said, you can back detail right off to -7 which really means the camera is applying no artificial sharpening or edge detail to the recording.

I run detail at -3 or so most of the time anyway.

-7 will be softer but your edges will key much cleaner. Crank in a bit of sharpness in post after your key and you're good.

Test, test and test again.

Tex.
 
F stop can be a tricky thing. You generally want to have a pretty deep DOF when shooting green screen because a key is generally much cleaner when the edges are there. Trying to key something when the persons eyes are in focus and the hair at the back of their head isn't can be tricky. So i try to go between F4-F8 and keep my subject in focus from front to back.

Your choice of lens will depend on what perspective you want to have and also, since we're dealing with practicality, how much space you have to shoot with.

Is there a lot of motion in the shot? If so i tend to go more on the 1/60th of a second @ 24fps than with 1/48th, simply to help with the motion blur artifacting. It helps the motion blur factor without heavily affective the way motion looks.

Get some distance between the subject and screen. Sometimes it's very hard to light a green screen perfectly even from side to side because we don't all have a truck load of lighting equipment and space. Also doing this throws the screen slightly out of focus which helps diffuse the gradient across the screen if it's not perfectly lit.

Have a contrast between your background and the edges of your subject. You will have an easier time keying if they are not at the same IRE. A background at 50 IRE and shoulders that are also at 50IRE will be more difficult to key than an edge that's at 65-70 IRE or even 30.

On the post side of things, learn how to do multiple layered keying. You generally want one key to eliminate most of the green, another layer for the edges of your subject, and sometimes even one more for masks depending on reflections and translucency of skin or clothes.

And most importantly, do as much testing as you possibly can. Then come back here to post your results!
 
Thanks very much everybody. Thanks Texwhitney, and thanks PaPa for the detailed explanation. This will very much help me and other people like me who are just getting into green screen shooting. Will test and upload to vimeo in the next few days. Thanks again everyone.
 
Just wish to thank everyone again for all your feedback. In my latest test, after dialing the AF100's detail all the way down to -7, and then applying a 20% sharpen filter in FCP7, the noise is all gone and the picture is sharp. Dialing down the detail proved more effective than anything else I tried. Will be posting my results shortly to Vimeo. Thanks again!
 
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