It's pretty common knowledge that uneven lighting, wrinkles, and motion blur can ruin footage shot on green screens, but outside of the basics, what else should you look out for? Luckily, our buddies over at Film Riot have a bunch of less ubiquitous tips that'll keep your shots looking sharp instead of like a hot green mess.
If you're at all familiar with green screening, you probably know that lighting is key (pun intended, kind of). Evenly lighting the screen is essential for optimal results, but what types of lights should you use? Connolly says he uses cooler lights on the backdrop and warmer lights on his subject. (If you want a cheap DIY solution for a 3-point lighting setup, our favorite practical effects master, Joey Shanks, has got you covered.)
If you don't like working with screens for whatever reason, get yourself some green screen paint. Prices range from $50 to over $100 for a gallon or less, but here's a DIY solution that'll save you a ton of money: grab $20, go to a hardware store, and buy a gallon of matte paint (something that is least reflective) that closely resembles (or is) chroma key green -- that's what I call it. In the video below, uploaded by MediaFi Productions, it's called "Sparkling Apple."
Film Riot also shared this video several years ago containing 10 green screen tips, some of which aren't mentioned above, that are really, really helpful, like how to clean up any spill by adding a hue and saturation to your clip, selecting the green color, and bringing down the saturation in post.
Got any green screen tips that weren't mentioned in the videos above? What simple and inexpensive techniques and tools work like a charm and which should we avoid? Share your expertise in the comments below.
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The more space you can put between Your subject and the Green screen the easier your life will be, I can help keep the green cast from the screen reflecting on to them.
Kinoflo has a great article on how to setup their lights for green screen, but the figures they present can help as a ball park for any light brand you use. Their lights also have bulbs idealized for the green screen and blue screens.
"the rule of thumb is to place the fixtures in front at about half the distance of the screen height, with the fixture tilted down at a 45° angle. For example, if the screen is 20ft (7m) high, the lights should be hung 8-10ft (3-3.5m)
in front of the screen."
September 7, 2014 at 9:17AM, Edited September 7, 9:17AM
Great advice! Thanks David and Steve.
September 7, 2014 at 1:31PM
Having a camera that shoots the highest bitrate and resolution possible doesn't hurt either. That's why I love my BMPCC. Though I think working with a lot of bad quality H.264 video can teach you a lot about keying and compositing. This is something I shot with a 50mm (cropped to around 150mm on the BMPCC 16mm sensor) at f1.4.
I was able to key out the blue sky even with all of the shallow DOF and 180o shutter motion blur. Everything behind the tree and the Raven have been comped in. Something that never would have worked with an overly compressed source... Also Red Giant Primatte and Key Correct helped a lot too.
September 7, 2014 at 5:01PM, Edited September 7, 5:01PM
It's amazing the final result. Good work! I have de BMCC and the keying it's easier ...
September 8, 2014 at 2:20AM
Can't remember where I came across this but one technique I find very useful with Keylight is as follows:
1. Duplicate the foreground layer
2. Do a very rough key on the topmost layer, clamping the white and black areas aggressively
3. Grow the screen (white) outwards
4. Set the top layer as the track matte in the layer underneath
The result is you get a thin green halo around the subject on the layer below (a sort of verdant Ready Brek glow, for UK readers!) that is then much easier to key.
September 8, 2014 at 12:56PM, Edited September 8, 12:56PM
lots of great starter tips... but if you're doing an exterior comp / scene, don't shoot in studio, if at all possible, always have your subject and screen in the type of environment you're actually aiming to have the comped shot.... Also be careful of the 'discount' options when it comes to paints... MATTE is an absolute must. You'll get an overwhelming amount of spill from anything cheap. Please please please stay away from using construction paper or things of that nature as well....
Lastly, if you're going to have camera movement, or tall actors, make sure you have taller then 8 ft of screen, otherwise, you'll be doing a lot of roto to cut the tops of heads out during low angles....
more of a comping tip, but if you don't have access to red giant's primate suite (get it if you can't afford nuke, it's way better then keylight) you can do a 'poor man's' light wrap by duping your keyed footage, filling it with black, and applying an outter and inner glow layer style. Then, dupe your BG comp and use that black filled pre keyed footage as a luma matte, and you have a pluginless light wrap. Set the BG to soft light....
just some dirty tips... but for effs sakes... please listen to the "fix it in production" advice... You might think a green screen is cheaper up front, but I promise it's 10x more expensive to fix after the fact.
September 8, 2014 at 3:00PM, Edited September 8, 3:00PM
Aye. Plenty of issues on my shoot, but c'est la vie. https://vimeo.com/104496214
September 13, 2014 at 7:55AM