December 4, 2014

Advanced Lighting Tips That'll Help You Pull the Perfect Chroma Key

When working with green screen, lighting is everything. (Almost)

The basics of pulling off a good chroma key are pretty straightforward: light evenly, put some distance between your subject and the green screen, etc. But, how do you know if you're lighting your scene evenly? If you said, "Um, just look at it with your eyeballs, dummy," you might be in for a very frustrating, very expensive and time consuming surprise in post.

That's why this lighting tutorial from director/cinematographer Matthew Rosen is so helpful. In it, Rosen shows you how to use a waveform monitor to make sure that your chroma is balanced, how to expose correctly using color bars, and how to set your shutter speed to reduce motion blur. (Rosen says "shutter angle" which is essentially the same thing, only it's typically the term used when using film cameras -- or Blackmagic cameras.) Check it out below:

Remember to consider this before you start setting up your green screen: your needs are going to change depending on how large of an area you're trying to pull a key from. Rosen's area is pretty big -- considering the size most low-budget filmmakers and web series videomakers use -- and because of this, he had to use a lot of lighting to properly expose the screen and balance the light. Now, if you're going for the size of a medium shot to a close up, you're obviously not going to need as much lighting. If you're trying to get a wide shot or larger, you're going to need more. 

If you're a professional who works in a large studio and has access to the lighting gear used by Rosen in the video, excellent! The video definitely gave you some tips that you can try out on your projects. However, if you don't have access to this type of equipment, you'll have to find some cheap and easy lighting workarounds, and we've got a ton of them here in our archives.

How do you light for a chroma key? What kinds of lights, materials, cameras, etc. work best, in your opinion, when working with green/blue screen? Share your tips in the comments below.     

Your Comment

12 Comments

It's not so effect now, but years ago, I had good luck using a cellphone camera as a crude light meter for a greenscreen. When your sensor only gives you 3 or 4 stops of range, subtle lighting irregularities really stand out.
I'd scan the scene with my phone camera, looking for hot spots or shadows my eyes missed.
Now that smartphones have his the scene and cameras have gotten a lot better, this technique isn't nearly as effective.

December 4, 2014 at 6:39PM, Edited December 4, 6:39PM

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kyleclements
Artist / Photographer
953

I've had good luck with an app called Green Screener. It more or less compresses the video to give you banding and show where the light falloff is. I used with a light meter to doublecheck the work, but I'd trust it on its own.

December 4, 2014 at 9:04PM

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Chuck McDowell
1st AC
513

I confirm Its amazing app I used it in professional set...

December 5, 2014 at 4:00AM

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Ammar Quteineh
Director|Cinematographer |||France|||
717

This is great.

December 4, 2014 at 9:43PM

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Steven Bailey
Writer/Director/Composer
986

We own a large 3000sq ft permanent green screen studio in Ohio and we have done a lot of keying, one of the process is to light the background evenly then the subject/foreground. In post using key light to key out the green and then apply a video denoise, then add background in and color correct both. From using old camcorders to dslr to red cameras, keying was never an issue, it's just a matter of time. Sometimes you may need to do a bit of masking if you failed to key right.

Our recent project is a Doctor Who Fan Film that has a bunch of scenes shot in the green screen and using the gh4 shooting in 4k downscale in 1080. We did all the keying in4k and it was easy and clean.

December 6, 2014 at 8:36AM, Edited December 6, 8:36AM

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Johnny Wu
Director, Producer, Editor
380

You denoise before you composite? Why is that?

March 8, 2015 at 9:31AM

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Karel Bata
Director / DP / Stereographer
535

Very helpful. Many monitors have waveform monitors built into them. Now I know how to use it with a green screen. Also, angling the cloth to make it easier to light is brilliant.

He mentions setting the shutter to 90 degrees so the edges are sharper with less motion blur. Had not thought of that.

I like running my GH4 in degrees of shutter angle instead of fractions of a second so the shutter is always at the right "angle" regardless of frame rate. Keeping the shutter at 180 degrees when moving between 24fps, 30fps, 2fps fast motion or 96fps slow motion means the motion blur is always correct. I also like how the GH4 allows you to put the shutter speed control on either the rear (default) or front adjustment wheels. As I keep the shutter at 180 most of the time, I moved its control to the less-used front wheel and control f/stop with the much more convenient wheel under my thumb.

The Sony FS700 can also read out in degrees.

December 7, 2014 at 8:50PM

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I use a product from Hollywood Camera Work called Green Screener. It runs on smart phones and is a decent, affordable tool. http://www.hollywoodcamerawork.com/gs_index.html.

December 8, 2014 at 9:49AM, Edited December 8, 9:49AM

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I can see 2 potential negatives to the wonderful advice provided by Matthew Rosen... by leaning the green screen forward, would that not increase the wraparound of green spill over the top of the actor? And by decreasing the shutter angle, the look would change to something more stylized and the chances of strobing would increase. This of course wouldn't be a problem if the look were stylized to begin with, but might be a consideration for something more natural. I'm just playing devil's advocate here, since Matthew is far more knowledgeable about green screen shooting than I am.

December 11, 2014 at 8:28PM

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Scott Ressler
Director of Photography
266

In Rosen's example, the talent was far enough away from the green screen that even with the tilt there was no way there would be a problematic amount of spill. Even in a scenario with a smaller setup, you could probably get a good amount of forward tilt without too much spill.

The motion blur issue is easily fixed by adding motion blur in post. In After Effects it's as easy as checking the motion blur selector for the desired layer :D

August 14, 2016 at 1:43AM

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Cooper Hansen
Camera & Steadicam Op
81

I like the idea of tilting the screen forward. What I would like to see is the lighting setup for the huge chroma sets like in the Avengers.

December 13, 2014 at 2:55AM

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Ryan Gudmunson
Recreational Filmmaker
669

Composing feet is always problematic - they can easily seem to not be attached to the floor. I've found that getting your subjects to wear dark or black shoes helps because the shadows then blend naturally.

March 8, 2015 at 9:34AM

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Karel Bata
Director / DP / Stereographer
535