People don’t buy what you do. They buy why you do it.” Simon Sinek
Let’s face it, green screen is cool. Whether it’s Sandra Bullock and George Clooney chatting in outer space, Tom Cruise climbing a skyscraper, or a weather reporter interacting with a virtual tornado, we’ve come to expect special effects that look like the real deal in movies and television.
But what about in online courses? Is the special effect of green screen ever worth the time, trouble, and extra money? I’d vote yes, but only if it significantly improves the quality of the lesson. As Simon Sinek implies in the above quotation, it’s the “why” that counts.
On the other hand, if you’re only using green screen to add razzle dazzle to your online course, you’ll burn a lot of time and money for something that doesn’t aid the learning one whit—and may even distract from it.
Why Use Green Screen in an Online Course?
When weighing the pros and cons, the simplest question is perhaps the most important: What can your students learn because of the green screen that they wouldn’t fully grasp, or grasp as well, without green screen?
In some cases, this may mean putting your teacher on green screen so that we see an environment and gain a sense of time and place as a result. In others, it might mean creating animations that the teacher appears to interact with, such as a virtual brain, the cosmos, or an African savannah—all examples from Teaching Company courses.
When you are puzzling this out for yourself, consider the aspects of your content that are the trickiest to explain. Have you ever wished you could just put your students inside something so they could see it for themselves? Have you imagined the perspective you could share if you had a virtual model of something—maybe the inside of a volcano or the streets of Paris during the French Revolution?
If so, you may have good reason to teach using green screen. When you consider the challenges of connecting with students online as opposed to in person, you can add another reason why it can be worth trying.
How Does Green Screen Work?
The principle is actually simple: combine images from two sources into one image by stacking one in front of the other. The image on top must be transparent in sections so that the one in the background can show through.
By taking out green (or other colors) in the foreground image with a chroma key filter, those sections become transparent. Then the foreground image is combined—composited—with the background image for the final effect. The background image can be static, video, or animated.
Why bright green? Not a lot of people wear that particular hue, so it’s used most often. If your clothes match the background (or are even closely matched, such as bright yellow or gold jewelry), they will “key” out—causing a spot where the background can show through. You can use other colors (blue is also common) if you need to show a lot of green in the foreground image.
You don’t have to have high-end cameras and editing software to make green screen effects. You can create them with an iPad, iMovie, and an app such as Green Screen by Do Ink.
For this week’s blog, I turned to three experts for their advice: John Sacco and Adam Schreck, both of whom I worked with at The Teaching Company, and my sometime-collaborator, producer/director Zach Wolfson. With their help, we can better understand green screen and how to use it.
John Sacco: Green Screen v. Virtual Sets
“Here are some things to consider when deciding to use green screen or chroma key technology. What is the motivation? Is it a way to have multiple set looks to keep the viewer engaged or lower cost in set production? A lot of short videos are just using a white limbo background these days to give a clean look.
“Many people confuse green screen with the fully virtual environment. In the former, the presenter stands in front of a green wall or cloth and their movements are confined to the parameter of the green screen. The technology works as described previously.
“In the latter, the presenter typically only turns slightly but doesn’t walk around. The work of creating the environment is done live, using camera angles and focal length to create the illusion that the subject is actually in the space created. The environment is fed in during recording, as opposed to being created later during editing, and different backgrounds can be fed through each virtual angle.
“For example, if the presenter is looking at Camera 1, there may be a virtual video screen behind him. Turn to Camera 2, and the audience sees a room-sized window looking out over a moonscape. Turn to Camera 3 and it’s a virtual ‘workshop’ where we get to see tight shots on virtual items the presenter interacts with. This eliminates the need for the presenter to move in the virtual world, but allows the world to move around him.
“The presenter typically watches a monitor off screen to see what he/she is interacting with. Presenters must move slowly and deliberately from mark to mark—this is a skill that needs to be rehearsed in a virtual world.
“If someone is just speaking in front of a green screen and the action is happening around him (think Neil deGrasse Tyson presenting within the cosmos), it becomes much easier for the presenter, but equally more dynamic for the viewer. The impossible becomes possible in virtual land. Brains float by, zoom in and can be dissected to illustrate easily what would be a complex explanation without the illusion. For example, the student along with the presenter can be transported to outer space to see how a black hole works up close and personal. The more purposeful you are, the better it looks.
“Tip: Create an image of a room slightly out of focus behind the presenter and the illusion they are in that space becomes more realistic. (If you were really in that space it wouldn’t appear as sharp on camera as the person in front of it, right?)
“Tip: With simple green screen (not virtual) the subject can only move within the fixed framing. The camera cannot physically pan, zoom , tilt or move in any way. It must be “fixed” to keep the illusion. That said, with current digital editing and post-production techniques, simple movements can be simulated in the editing process.
“NewTek makes an affordable Tricaster system that can create green screen productions from just using a computer and a keyboard.
“Rendering is only necessary if you are doing the chroma key in post. The Tricaster and most production switchers are capable of doing the ‘rendering’ in real time. That’s what makes green screen productions quicker and cheaper.”
Adam Shreck: Tips for Shooting Green Screen
“Tip: The green screen itself needs to be as flat/uniform (surface) as possible. It’s easy when it’s painted on a wall, but if you’re using fabric or a screen, make sure there are no wrinkles or gradations in texture/color. The surface must be as uniform as possible.
“Shoot in the highest resolution your workflow can accommodate (at least 1280 x 720, higher if possible), because that makes keying easier. The more visual information your NLE (non-linear editing) program has to work with, the better the key will be. Avoid subject shadow on the green screen.
“Tip: Whenever possible, avoid quick, frenetic subject movement. The motion makes it difficult to key properly, and you may find parts of him or her disappearing into the virtual background.
“Tip: Be sure to shoot test footage and take it all the way through the process of pulling the chroma key to ensure results are as intended. Make adjustments as needed before shooting final video.”
Zach Wolfson: Effectiveness and Timing Tips for Green Screen
“In the simplest way, a green screen allows us to create the illusion of a more interesting background behind the talent (you) on camera.
“But there’s a potential danger for your audience as they’re watching and learning from you: If you don’t plan and film with a green screen well, people can tell that something feels fishy about it. Maybe the lighting wasn’t set up quite right, or the chroma key to pull the green out of the image is a bit off, and there’s a weird halo around you.
“Your viewers will wonder, ‘Why does she look weird against that background? Something is off about it.’ And instead of focusing on what you’re teaching, they’ll be distracted by the visuals.
“Go slowly and be patient with yourself while shooting. If you feel rushed, things like the lighting and the delivery can start to get sloppy. That will only create problems in post-production, and it could lead to having to reshoot parts of the script, too.
“Tip: Take the time you think it’ll require to shoot, and double it (true whether you’re using green screen or not). Then you’ll probably be close to the amount of time you’ll spend filming.
“When you get into the post production stage with your green screen footage, plan to at least triple the amount of time to edit this video compared to one without green screen footage. Even the simplest visual effects require time to shape and craft the image to make it look its best.”
Zach Wolfson: Staging and Lighting Tips for Green Screen
“Tip: Iron or steam the green screen to remove any wrinkles, and hang it so it creates one solid color behind you.
“Many green screens will have a green side and a blue side. This gives you options for the presenter’s (your) wardrobe that’s worn on camera. If you’re wearing anything green, use the blue side of the screen. And similarly, if you’re wearing any blue, use the green side of the screen.
“Tip: Set up your green screen set in a space that allows you to have enough distance to separate between the presenter (you) and the green screen.
- Separation is essential when you start lighting your two zones of the set.
- Ideally it’s great to have at least 5-6 feet between the talent on-camera and the green screen behind him/her.
- This helps to prevent what’s called ‘color spill’ or a green/blue color tinge on the talent’s skin/hair/wardrobe.
“Tip: Create separate lighting zones for your background and your presenter (you).
- Set up your camera and green screen at the same time before bringing in any lights. Your camera is your best friend—look to it as you light to see exactly what it sees.
- Once you start lighting with your video lights, turn off any lamps in the room that create ambient light (overhead lamps, desk lamps, floor lamps, etc). That way the only sources of light on your set will be your video lights.
- For filming against a green screen, you need to create two distinct lighting zones: one for the background, and one for the talent (you). Multiple lights can be used in each lighting zone, and it’s important that the lights in the background zone don’t illuminate the subject zone (and vice versa).
- When you light the green screen, the goal is to create a soft and even amount of light across the screen. Look at your camera’s LCD screen and the exposure should be even across the image (no hot—overly bright—spots).
- You’ll likely want to use at least two lamps to light the green screen: one on either side of the green screen.
- Once the green screen looks great on your camera, now bring in your lights for the talent (you). Use at least two lamps to light the talent, too: one as the key light (the primary), and one as the backlight that creates separation (color contrast) between the outline of the presenter and the green screen behind them.
- With your talent (you) in place on-camera, try having each lighting zone on, one at a time, to confirm that they are not affecting each other.
- When the talent lighting zone is off, stand in on-camera and you should be a solid black silhouette on screen.
- When the background lighting zone is off, stand in on camera and you should be lit beautifully and the background behind you should fall off into darkness (dark grey or ideally black).
- If there is light spilling from the lamps from one lighting zone to the other, consider using large pieces of foam core to flag (or block) the light between the zones, just out of frame for the camera.
“Now once you have the green screen and lighting set up, bring in any other gear that you’ll need to film (shotgun mic on a boom, laptop with your script, etc.).
“Tip: When you’re done filming, it’s best if you can leave your set and not take it down.
- If you have to reshoot for any reason, it will be much easier to match whatever video from the original shoot is workable.
- Also, it’ll be simpler and faster for you the next time you film.
- If you don’t have that luxury, take photos from multiple angles to refer back to the next time you set it up.
- At a minimum, mark on the ground with masking tape where you have the camera/tripod and where the talent (you) stands on-camera.
“Only use a green screen for your videos if it’s for stylistic reasons that directly support the valuable content that you’re sharing with your audience. Make it about your audience first and let the production quality support the value you’re bringing them.”
Zach also offered to answer any questions about gear, using a green screen, or anything else related to making videos. Leave your questions in the comments of this post and he’ll jump in to answer them.
I hope you found this blog helpful. Please send me your questions for future issues, and tune in next Friday for Issue #23 of “Everything You Need to Know to Create Outstanding Online Courses.” We’ll continue learning from our contributors by looking at their guidance and tips for postproduction with green screen.
Want to learn how to make great online courses? To get your free copy of “12 Steps to Killer Course Content,” and weekly tips, click here.
Marcy McDonald is an Online Course Producer. She helps Subject Matter Experts and Professors create online courses with better content, delivery, and production, for better teaching. She’s developed ~450 online courses for lifelong learners, worked in video and audio studios, and filmed in the field (literally).
Contact Marcy for help crafting your online course: https://www.marcymcdonald.com/contact.html
Please check out my contributors (in alphabetical order):
John Sacco, Video Production & Operations, LinkedIn profile
Adam Schreck, Multimedia Guy, www.adamschreck.com