Green Screen Questions

D

Deer Film

Well-known member
Hello, I am trying to perfect my green screen techniques. Quick question, if I have jaggies on my subject, I assume this is do to spill. Is spill referred to a light that is hitting your green screen to hard and bouncing back to hit your subject. So then is the trick is to light your green screen with just the right amount of soft light. I don't have a huge amount of room, I am trying to stand 6 feet away. I have lights hitting my green screen, and then 2 Fovitec 1200 LED lights with Softboxes hitting my subject. My green screen is keyed perfect. I have a painted wall, but also a collapsible green screen. My only problem is the jaggies. I am using BBC in Sony Vegas, but also tried Chroma Key Pro and after effects. So I assume I need to adjust the light hitting the green screen. Has anyone had any issues like this.
And curious to know what your favorite Chroma Key software is?
 
I don’t deal with the post end...

The key to green screen, no pun intended, is to separate your subject from the screen. Space/separation is non-negotiable. I’ve told people this numerous times. If you can’t provide the space to separate the subject and screen, you’re wasting your time and money. I’ve even been brought in to re-shoot other peoples green screen projects, because they couldn’t pull a clean key. And when I asked them about the original shoot, it was always that it was in a small space and the subject had to be close to the screen. Most of the time you want at least 7’-10’ separation between the subject and screen. More is better. Have good(deep) depth of field and a good hair light/edger to give good clean separation from the edges of the subject and screen. We also used to use like 1/8 or 1/4 minus green gel on the hair light to help just in-case there may have been a little spill/contamination, but I haven’t done that in years. Also, use a waveform and false color to make sure your screen is lit as flat and evenly as possible.
 
My setup is in a small space, but I got it well lit and perfected (for Me). The only problem is why the jaggy edges. Like I said before, I use a canon vixia G30 HD video camera. Well, today, I just got a Sony ZV1 and shot the same set up in 4K...WOW, I slapped on the BBC Chroma Key filter in Vegas, and did not have to adjust a thing. All edges are smooth. I almost cried because I was finally getting a perfect key. Now I want to know why? It is hard for me to believe that the Vixia can't make a good camera for green screen, but it is over 9 years old. That little Sony does such a good job.
 
I the stuff I shoot doesn't warrant green screen, and to be honest, I'm a little scared to try it on a paid gig knowing how badly it can go.

Here's a few not yet mentioned tips that I have yet to put to the test.

Use full spectrum lights like tungsten.
Mount your camera vertically with an L-bracket or pan-tilt head to maximize your camera's resolution (assuming you just have one person standing or sitting in the shot).
Light your green screen with RGB lights set to green (you definitely need a lot of distance if you try this).
Consider renting a 4:2:2 10-bit 4K camera next time.
 
Hi, honestly I am getting SUPER great results for what I need now, the 4K camera made it so easy. I have 2 1200 Daylight LED softboxes on the subject, 2 led with diffuser lighting up the green screen, Subject is 6 feet away from green screen. I also have green workout mats for the floor. I tried dancing and moving a lot, works great. Now I get to have fun creating some cool composting. Thanks for your help.
 
Screenshot 2020-06-17 at 19.33.50.jpgI've got to suggest a few differences from Imacuser - I light my green screens with either tungsten, as he mentions, but I actually get better results from washing the screen with green LED, because as LED contains only that one colour spike, it actually keys better.

However - all keys are not equal and jagged edges are usually keyed artefacts.

A bit of history, if you forgive me. Back in the early 2000's a company in California called Serious Magic were a bunch of trendy clever folk who were producing virtual studios and had created an excellent chromakey algorithm and it did amazing keying. I paid a lot of money for it and it had so much adjustment to enable good jagged edge free keying from even poorly lit screens. Then, Adobe bought the company and scrapped the virtual studios, just to build in the ultra keying to Premiere.

I included a control box from the ultra keyed in premiere with all the various parameters, and this does enable closer screen to subject distance and still have sharp edges, and you can filter out lots of the spill. In my small green screen area in the audio studio, Ultra gives me very sharp keying with my front light being tungsten and the green screen light LED green (although being fair, tungsten screen light was fine, but just difficult to make even from the close distances.

Soft lighting for the screen, and angles for the subject where shadows on the green screen are soft, are vital. Ultra copes with hard shadows on the green screen quite well, but soft stuff is always better than hard - yet with small spaces hard edges are too easy to create.
 
thank you, I always enjoy reading your comments. I will try premiere. Just a guess, but since I had great results with the Sony 4K now, I wonder if it is the Canon Vixia g40 and how it handles. I did apply a .50 Gausian Blur and that seemed to help the footage a lot, but I really like the look of the 4k. I always tell me wife about graphics, when I have challenges in finding the answer, I know there is an answer and different ways to get a result. It's fun once you find an answer. Now I can go have fun with my green screen set up.
 
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