If you’ve been shooting your own green screen interviews, talks, and explainer videos for a while now but find yourself tearing your hair out in post-production frustration, you’re not alone. Sometimes the simplest missteps during a shoot can lead to long-term consequences demanding costly and time-consuming fixes in the final stages. To help you head off any future issues, learn from others’ experiences. Here’s a thorough list of common green screen mistakes and how to avoid them.
So many postproduction problems can be eliminated through the proper use and distribution of lighting. When the light is uneven on your green screen back drop or cyclorama wall system, shadows and hotspots are generated that make it difficult to draw a proper key later. Make sure your lighting keeps the backdrop well-illuminated without making any spot brighter or darker than the rest. Two lights set on either side off-screen should do it, but as the space increases, the so does the demand for even lighting.
Once the green screen is well-lit, make sure your talent, props, and scenery aren’t ruining your shot by casting shadows on the background. Once again, this can affect the chroma key process, leaving things looking fake. Make sure your actors and objects are at least eight feet in front of the screen or the cyclorama wall system, as this makes it more difficult for them to cast shadows. Ensure the lighting on your talent isn’t too bright as well and add a third or fourth light on the side to dispel any shadows, if necessary. Plotting the lighting beforehand is a good idea but be ready to be flexible and move the lighting as required. Consider the role of gels as well, which can lend different seasonal feeling to a scene—all while avoiding green lighting, of course.
Now we enter the “too much of a good thing” portion of the article. Color spill happens when lighting causes the green screen backdrop to reflect on the subject, giving them a sort of fuzzy chartreuse outline or weird lime halo. This can make the scene look extra fake, and it’s tough to fix afterward. During the shoot, however, simply add some distance between the subject and the screen and reduce the intensity of the lighting. As a tip, don’t have your subjects stand on a green surface, which can reflect upwards and give them that Martian skin tone. Green props and furnishings should have already been eliminated, but make sure that any props present are nonreflective as well.
Green Clothing or Reflective Jewelry
One of the simplest rules about green screen photography and filming is this: never, ever wear green. Green screens are green because humans aren’t, and it’s a color that does not naturally occur in human skin or hair. Unless you intend for them to be invisible (for the sake of special effects or the like), onscreen talent must never wear anything green, or else the background image you add later will appear on the body. The same can be said for reflective jewelry and other shiny objects. These can also reflect lighting and green coloring. Ask your subjects to dress in anything but green—most film production experts recommend contrasting or pastel colors at opposite ends of the spectrum from green—and to surrender any sparkly baubles until after the shoot.
Motion blur happens when your talent moves too quickly and the camera can’t keep up, revealing the green screen trickery. The easy fix is to ask talent to slow down their movements, but this can look weird when overdone. Otherwise, this is a relatively easy technical fix. Decrease the aperture and increase the shutter speed on your camera to shoot more frames per second, which can help get rid of that trippy “warp speed” effect.
Flaws in the Physical Green Screen
In general, keep the set clean and undamaged, for aesthetic as well as shooting reasons. Before and after the shoot, make sure your backdrop is still in good shape. If you’re using a fabric screen, use a steamer to eliminate any wrinkles or creases. If the green screen is painted on the wall, check for places where the green has grown lighter, scuff marks, cracks, pitting, and other damage, patch it, then repaint it. If you’re using a modular cyclorama wall system, do a spot check and see that all the cyclorama pieces are still attached and undamaged. Again, any damage can create shadows, and unnoticed shadows can throw the entire shoot out the window.
Stepping Out of the Scene
If an actor or subject isn’t paying attention, they can easily step away from the backdrop, putting part or all their body in front of a non-green screen part. Leaving the frame is a more general issue than a green screen one, but it can demand extra work during post-production by moving the talent back into the frame with the editing software and reconstructing the background. But that’s why you should always do multiple takes. Unless you prefer dealing with the time and expense demanded by reshoots, mark the floor and boundaries of the frame for your talent and keep an eye on them so they don’t stray.
This one should be a given, but if you haven’t set up the camera properly and aligned the screen within the frame, you’re only setting yourself and your talent up for a wasted morning, afternoon, or evening. Most production experts recommend writing a script and then storyboarding your shots, so you have a reference for setting up the camera and set. Stick to a plan!
One last thing about common green screen mistakes and how to avoid them. Experts agree that when working with talent, you should always hire a makeup artist. We’re not talking about someone who can turn actors into aliens and werewolves with rubber masks and glue (though, if you’re creating that sort of science fiction or fantasy production, maybe we are). Find someone who knows how to create and apply makeup that works best for a green screen film shoot. They’ll ensure your speakers aren’t shiny and reflective, and they’ll know how to manage the flyaway and light-blonde hair that usually produces color spill and motion blurs that can make a professional video look like amateur night.