Greenscreen Advice

Hi all, im about to shoot on greenscreen with my bmcc. Any suggestion for lenses? Im going to shoot full shot. Im preparing some lenses like canon 16-36, canon 70-200, tokina 11-16. Im gonna use prores log for my entire shots. how bout the film or video mode? which one is better for greenscreen work? I would also like to know where i should set my aperture to get the sharpest image? please advice and sorry for these noob question.


Thanks in advance

Hi all, im about to shoot on greenscreen with my bmcc. Any suggestion for lenses? Im going to shoot full shot. Im preparing some lenses like canon 16-36, canon 70-200, tokina 11-16. Im gonna use prores log for my entire shots. how bout the film or video mode? which one is better for greenscreen work? I would also like to know where i should set my aperture to get the sharpest image? please advice and sorry for these noob question.


Thanks in advance

A web site like the German site for Photozone will likely show you the sharpest aperture for each of those lenses. Prime lenses would possibly be sharper. Typically the lenses are sharpest when stopped down about two or three stops. Try to avoid stopping down more than f/8 if you can. The actual lenses you use depend upon your needs and how you want your image to appear.

Shooting 2.5K raw might be the best choice for doing green screen if you want to consider that. If shooting ProRes, then choose the Film mode (that is ProRes log).

Rick Lang
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I would also highly recommend shooting raw for greenscreen work.

My suggestions for greenscreen work with the BMDCC:

(1) Shoot RAW. It's much more forgiving, and it makes it easier to get a good final result.

(2) If you have an iPhone/iPad, get

to get even lighting quickly.

(3) Verify the finished lighting with a scope.

(4) Use a light meter, and expose the green screen 1 stop under the foreground's key light.

(5) Put the foreground subject far enough away from the green screen that when you turn off the key and fill, the subject is a black silohuette in front of the green screen. If you see any green light wrapping around the subject, either move them further away, or take down the exposure of the greenscreen.

A web site like the German site for Photozone will likely show you the sharpest aperture for each of those lenses. Prime lenses would possibly be sharper. Typically the lenses are sharpest when stopped down about two or three stops. Try to avoid stopping down more than f/8 if you can. The actual lenses you use depend upon your needs and how you want your image to appear.

Shooting 2.5K raw might be the best choice for doing green screen if you want to consider that. If shooting ProRes, then choose the Film mode (that is ProRes log).

Rick Lang
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So what is the best F stop? f/8? and about shooting in film mode, isn't it too flat image? im afraid i can't separate the green color.

Thanks Rick

I would also highly recommend shooting raw for greenscreen work.

for sure. but unfortunately we don't have such a proper machine to work with RAW for now

My suggestions for greenscreen work with the BMDCC:

(1) Shoot RAW. It's much more forgiving, and it makes it easier to get a good final result.

(2) If you have an iPhone/iPad, get

to get even lighting quickly.

(3) Verify the finished lighting with a scope.

(4) Use a light meter, and expose the green screen 1 stop under the foreground's key light.

(5) Put the foreground subject far enough away from the green screen that when you turn off the key and fill, the subject is a black silohuette in front of the green screen. If you see any green light wrapping around the subject, either move them further away, or take down the exposure of the greenscreen.

Thank so much for the advice!

My suggestions for greenscreen work with the BMDCC:

(4) Use a light meter, and expose the green screen 1 stop under the foreground's key light.

That may be standard practice, but I find with this camera that you don't want the greenscreen to be noisy or that will interfere with the key so make sure you have the greenscreen lit to above 50 IRE. 60 preferable.

Hi Paul, any suggestion which lense should i use for taking a full shot? I have canon 70-200,16-35, 100 and tokina 11-16. and what aperture would be the best? Thanks

Hi Paul, any suggestion which lense should i use for taking a full shot? I have canon 70-200,16-35, 100 and tokina 11-16. and what aperture would be the best? Thanks

That depends on how large the space is and how far you can move back. Many people don't like to shoot with shallow DOF on green screen because it can cause issues with edges. The reasoning is that if you have sharp edges (not out of focus) then they'll be cleaner when you key (no green spill blending with the foreground element). Aperture will depend on what the scene calls for.

What exactly are you shooting? Does it call for shallow DOF?

A web site like the German site for Photozone will likely show you the sharpest aperture for each of those lenses... If shooting ProRes, then choose the Film mode (that is ProRes log).

Rick Lang
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So what is the best F stop? f/8? and about shooting in film mode, isn't it too flat image? im afraid i can't separate the green color.

Thanks Rick

You have to look up the lenses you are considering and Photozone will show you the resolution at various f-stops and likely indicate the sharpest range. Some lenses are sharpest as wide as f/4 or less according to their design, most are sharpest at f/5.6, but it will just take you a few minutes to see what Photozone concluded.

You need to apply a look or minimal grade to the ProRes Film footage.

Rick Lang
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That depends on how large the space is and how far you can move back. Many people don't like to shoot with shallow DOF on green screen because it can cause issues with edges. The reasoning is that if you have sharp edges (not out of focus) then they'll be cleaner when you key (no green spill blending with the foreground element). Aperture will depend on what the scene calls for.

What exactly are you shooting? Does it call for shallow DOF?

im going to shoot some commercial video, will do a 2d animation (motion graphic) for the background. And i need to shoot it full shot to the subjects. i need to make sure even when i shoot them in a full shot and zooming the subject in post, i still can get the sharp images.

im going to shoot some commercial video, will do a 2d animation (motion graphic) for the background. And i need to shoot it full shot to the subjects. i need to make sure even when i shoot them in a full shot and zooming the subject in post, i still can get the sharp images.

You are likely to lose sharpness if you are zooming in post. I assume from what you have said that you cannot shoot the subjects with your final framing requirements.

Rick Lang
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im going to shoot some commercial video, will do a 2d animation (motion graphic) for the background. And i need to shoot it full shot to the subjects. i need to make sure even when i shoot them in a full shot and zooming the subject in post, i still can get the sharp images.

You are likely to lose sharpness if you are zooming in post. I assume from what you have said that you cannot shoot the subjects with your final framing requirements.

Rick Lang
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How can you lose sharpness if you don't go beyond 100%?

How can you lose sharpness if you don't go beyond 100%?

Marc, he said he wasn't shooting raw so I assume he is shooting HD video. If he is zooming in on the subjects in post, I assume he is not using 100% of the original frame. Hope that makes sense. Maybe my assumption is incorrect.

Rick Lang
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My suggestions for greenscreen work with the BMDCC:

(4) Use a light meter, and expose the green screen 1 stop under the foreground's key light.

That may be standard practice, but I find with this camera that you don't want the greenscreen to be noisy or that will interfere with the key so make sure you have the greenscreen lit to above 50 IRE. 60 preferable.

Interesting. Where on the scope do you like your keylight skin tones?

How can you lose sharpness if you don't go beyond 100%?

Marc, he said he wasn't shooting raw so I assume he is shooting HD video. If he is zooming in on the subjects in post, I assume he is not using 100% of the original frame. Hope that makes sense. Maybe my assumption is incorrect.

Rick Lang
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Sorry Rick, my bad assumption. I read back a bit and saw where he said he had no plans to shoot 2K raw. On some stuff (mainly Web delivered talking heads), I've been shooting 1080p and delivering 720p a lot l8ly. I get away with quite a bit of post zooming and positioning and have found that no sharpness is lost if I don't post zoom the 1080 beyond 100% in the 720 timeline. It's a wonderful technique that I'm certain you are very familiar with...that's what I was referring to. Sorry about the confusion.

Sorry Rick, my bad assumption. I read back a bit and saw where he said he had no plans to shoot 2K raw. On some stuff (mainly Web delivered talking heads), I've been shooting 1080p and delivering 720p a lot l8ly. I get away with quite a bit of post zooming and positioning and have found that no sharpness is lost if I don't post zoom the 1080 beyond 100% in the 720 timeline. It's a wonderful technique that I'm certain you are very familiar with...that's what I was referring to. Sorry about the confusion.

Yes its for web purpose only. Im not gonna zoom it more than 50% for some framming needs. i think Your technique will be applied. The thing that i still confuse is whats the different if i shoot on film or video. Is there any different quality output?

Thank for being here for me, really appreciate your time

I get away with quite a bit of post zooming and positioning and have found that no sharpness is lost if I don't post zoom the 1080 beyond 100% in the 720 timeline. It's a wonderful technique that I'm certain you are very familiar with...that's what I was referring to. Sorry about the confusion.

Yes, that post zoom would work fine for a 720p timeline. Good point!

Rick Lang
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Yes its for web purpose only. Im not gonna zoom it more than 50% for some framming needs. i think Your technique will be applied. The thing that i still confuse is whats the different if i shoot on film or video. Is there any different quality output?

Thank for being here for me, really appreciate your time

Marc can add a comment if needed, but I don't think there will be much difference if your subject is well lit since the slight loss of dynamic range in Video versus Film modes may not be relevant for your subject and your background of course is replaced. With your 2D animation. You might want to test to see if there is a visual difference. Film mode will give you a little more control over your subject's look and that might be important to match with the animation.

Rick Lang
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My suggestions for greenscreen work with the BMDCC:

(4) Use a light meter, and expose the green screen 1 stop under the foreground's key light.

That may be standard practice, but I find with this camera that you don't want the greenscreen to be noisy or that will interfere with the key so make sure you have the greenscreen lit to above 50 IRE. 60 preferable.

Interesting. Where on the scope do you like your keylight skin tones?

70 to 80 but usually if you're over the noise floor, you're good. It's weird, but the BMCC seems to preserve detail all the way up until clipping so I'm not too strict as to where the skin tones land. It depends on the scene, but usually I like to keep the greenscreen high enough above the noise floor so you don't get noise/grain.

Certain lenses will give you better results too. My Leica 50, for example, will give me a nicer image than my Rokinon 24mm. It's hard to describe, but the Leica is more of a smooth, high detail, clean image and the Rokinon seems to have more of a sandy texture to it with more colored noise. There's something about those Leicas, man. They're sweet.

Tip I heard, never had a chance to try it.

Light the green screen with a green-gelled light. Easier to evenly light, less out of green highlights, less spill.

Again, I don't work with green screens, just a tip I heard from a buddy.

I hate to say it, but it sounds like you are going to mess it up. Blue / green screen is not easy to do well. Most folks mess it up trying to do it on the cheap with no experience. At least you will learn some things. More resolution and more color data (not subsampled) makes a big difference on green screen shooting. Massive compression that you can easily get away with on normal shooting will botch green screen footage. Green screen is hard -- know that.

Re: lighting, think first about the composited shot: what is the light? You must match that (on the subject(s)) in the green screen. If you do not, it will look goofy. Like everyone says, you want your green screen evenly lit, but more importantly, you want NO wrinkles or texture in it. You want it smooth, so fabric is not good unless you really spend some time keeping it taught, which is a major hassle. You have to get some distance between your subject(s) and the screen, which requires a big room and a big screen. Do you have that? It sounds like from your very brief description, that you are not using a realistic background in the composited shot, anyway, so maybe it does not have to be so good. The screen has to roll at the bottom (like cyc) if you show full body shots -- you cannot have a dark corner where the screen meets the floor.

Re: iris, it is better if the green screen is out of focus, since you need it to be as smooth as possible. Of course, your talent needs to be sharp, so a more open iris can help a bit here. As Paul said, you want no noise, either, so don't let it get too dim. Spill is reduced by keeping your talent away from the screen and using good matting software with spill killers that work properly. If your camera is locked off for the shots, it can provide a benefit in post when you are pulling the matte, but you can pull good mattes even with a moving camera if you do a lot of things well. Subject motion also aggravates green screen work. Providing a back light (and as jb said using the complementary color to your screen) can help reduce spill if it fits with the lighting plan of the composited shot.

I repeat, green screen is not easy if you want it to look something other than goofy.

Green scrren is honestly not that hard if you follow simple rules:

-You must light it evenly at the right level . the best way to achieve it is to use light meter and vectorscope. Use your vector scope to get the purrest green as possible. Use green filter on your background light.

-Avoid green color and green reflection on your subject. So no metalic part , no tanslucid part, no shinny part, avoid white shirt as much as possible. Place your subject as far as possible from the green screen. Use back light. Every part of the green screen wich is not hidden by the subject during the shot can be covered with dark or white sheet (depending on your contrast preference) and removed in post.

-sharpness: you want your subject as sharp a you can and your green screen soft( except if you use trackers, in that case you need your background to be a little sharp). When I have no time to test a lens for sharpness , i close it by 2 stops and a half.
Avoid flare as the plague-> matte box and flag.
In order to maximize sharpness , you have to get the most detail you can. For example, if i shot a human standing , i often put the camera at an angle of 90° from horizon. this way, i have more pixel filled with my subject and i can zoom way more in post.
If your subject do fast movement , you need to use a fast shutter. this way you can avoid as much as possible motion blur and add it it post.

But believe me , i have done green screen on crappy green with a 5D wich went not so bad, if you follow these rules , you wan't get too much problem with a 422 10bits signal. With the BMCC raw is definitly the way to go anyway.

Hi all, im about to shoot on greenscreen with my bmcc. Any suggestion for lenses? Im going to shoot full shot. Im preparing some lenses like canon 16-36, canon 70-200, tokina 11-16. Im gonna use prores log for my entire shots. how bout the film or video mode? which one is better for greenscreen work? I would also like to know where i should set my aperture to get the sharpest image? please advice and sorry for these noob question.


Thanks in advance

I think there is some really good advice in this thread. The best points (IMO) have been the following;

- smooth out your backdrop as much as possible... the smoother the better
- light your green screen evenly
- expose the screen above 60 IRE... not too hot though, try and stay below 70 IRE
- light your subject(s) separately (they should be completely in silhouette when the screen is fully lit)
- Don't remember if this has been mentioned, but shoot at a medium aperture. If I can help it, I always try to shoot between f4.0 and f6.3 for chromakey shoots... it depends on the subject(s).


Things I might stay away from (no offense meant to the original posters);

- DON'T throw the background out of focus... the primary job of the person pulling the key is to protect the edges. Edges that are too soft can present serious problems if your lighting isn't perfect or if you get color spill from the backdrop (and you probably will).

- DON'T use green or blue lights for chromakey, unless you have someone who has experience working this way. You will need lighting instruments AND a backdrop color that is designed to work together. Otherwise, you run the risk of shooting a background that really isn't completely blue or green.

Thanks,

Shawn

Cannot see why anyone would think that the background being out of focus would have any bearing at all on sharp edges of the subject in a green screen. It is precisely texture and variation of the background that causes problems with the key. It being soft helps that.

You care a lot about detail and texture (including edge detail and texture, as with hair) in your subject, so it has to be sharp, but the ideal background is a single color and brightness across its entire expanse.

Hey Rudy,

My advice would be that depending on what you're shooting it might be worth shooting in portrait rather than landscape. For example if you are shooting a single subject standing, flip your camera 90degrees and you will have so much extra resolution in post to play with.

Matt

And yet one more advice. With all that has been said in mind, go out there and do it. Experience is the best teacher. Get your hands dirty.