Using a Green Screen for your Video Presentation
Green Screening your
I thought I’d outline some key points in this article for those thinking about buying or using a green screen for your video presentations. I cover this topic extensively in my forthcoming book “How to Present on Video”, but this question was recently sent to me by a reader:
Green Screen Basics
A “green screen” can open up a world of fun, and creative possibilities. Sometimes known as “chroma keying”, it is a film production technique where you use a background screen (typically green or blue) that is distinctly different from the color of human skin.
This enables you to “key out” (remove) the actual blue or green background, and replace it with another background image or some other video footage. The technique is a staple of action and sci-fi movies, as well as TV news and weather reports.
Why Green or Blue?
Chroma key screens are primarily green or blue because these colors are furthest away from our own skin tone. You can also use other screen colors that are uniform and distinct but excluding red because it’s common in our skin tone. Bright green or blue colors have been found most effective in getting a “good key” provided that you or your subject is not wearing similar colored clothing.
Green screens are popular because current digital video camera image sensors are more sensitive to bright green, which can offer less visual “noise” (where the footage looks grainy), and produce a cleaner key in post production editing.
Blue screens can be problematic if the presenter has blue eyes. Also, the color blue is common in fashion clothing styles. I read somewhere that blue screens do work better for blonde haired people, but I haven’t been able to thoroughly test and verify this for myself.
Check your Strategy. Why do you want to use a fake background?
Before venturing down the creative rabbit hole of green screen “imagination land”, you need to get clear on your strategy first.
By its very nature, green screening enables you to insert a fake background image, and you are only limited by your imagination as to what you can insert into your footage.
But if you use this production technique in an attempt to fool your viewers into believing (and yes I have seen this) that the high-rise office with million dollar views, or the (bollocks) boardroom background, or the mansion with the exotic car collection is really yours – think again; your viewers will spot the fakery.
It takes great skill and production technique to sell this effect and most people simply don’t have the resources nor the film-making experience to do so. It’s the video equivalent of those booths at tourist destinations that take a picture of you and superimpose your favorite celebrity standing next to you. It just looks fake.
With your business videos you want to show your best self, but not present something that you are not. It only takes one falsehood for you and your brand to lose any credibility and trust you may have built up.
Actually, it’s extremely challenging to hide poor quality green screening on video. To do it well you must shoot excellent raw footage. Shooting high-quality raw video footage is the most important part of any video production, regardless of whether or not you choose to use chroma keying. Without high-quality raw footage, no amount of digital magic is going to give you a realistic effect.
I am of course assuming you are going to use green screening to help you communicate your message in a fun, creative way. So let’s get started with some of the basics.
Setting up your Studio Lighting is Key
I cover this topic in depth in my book. However following is a general overview:
When shooting on a green or blue screen, having even lighting and keeping your screen free from shadows and creases is paramount to successfully pulling off a green screen effect.
When setting up your lighting for green screening, think of it this way. Your screen needs to have its own dedicated lighting (2 to 4 lights), and you (the presenter) need to have your own separate dedicated lighting (2 to 3 lights). For more information on 3 point lighting for presenters, see Studio Lighting for your Video Presentations.
To achieve even lighting on your green screen, you need to ensure that your lights are of the same intensity (don’t mix fluorescent with halogen), that they stand at equal distance on either side of your screen, and that their positioning and angles mirror each other exactly in their layout.
For the green screen effect to work, you must have even lighting on all areas of the screen that will be in the frame. Check to avoid “hot spots”, which is where one area of the screen appears more lit than the other. Adjust the positioning of your lights until the screen is lit evenly.
For lighting my screen, I use 4 lights, with 2 on either side of the screen positioned at a 45-degree angle facing the screen. You can use 2 lights, but it really depends on the size of your room, and how much of your screen you are lighting.
The lighting product line that I currently use is an inexpensive entry level kit the EPhoto VL9004S3.
This kit comes with:
- 3 x Lightstand (able to extend to 6.5ft Height)
- 3 x 4 Light Sockets
- 3 x 16″ x 24″ Soft-box
- 12 x 45W 5500K (perfect daylight bulbs equivalent 2400W)
- 3 x Power Cords with Carrying Case
To date, I haven’t had any issues with this particular product line. However, the square softboxes do take up a lot of space in my studio. In the future, I plan to get a set of Flolights (panel LEDS). Yes, these are pricey, however, they make up for it in convenience (you don’t have to assemble soft-boxes), they take up much less space, are portable (you don’t have to disassemble them) and they give you more lighting options.
Common Lighting Mistakes
If the presenter stands too close to the screen, they will cast a shadow against the screen. Check to ensure that no shadows appear behind the presenter while they are standing in front of the screen.
Also, if the presenter stands too close to the screen – the screen can reflect (or spill) green onto your hair, skin and clothing. This green halo can be near to impossible to “key out”. To prevent this, position yourself at least 4-5 feet away from the screen. Standing this far in front will give you a cleaner, sharper key-line (outline) around your body.
Make sure the dedicated light source that is illuminating the presenter does not spill over onto your screen. You want to keep the illumination of the screen lighting, and the illumination of the presenter lighting as separate as possible. To do this, it helps to have a few feet of space between the presenter and the screen lighting. If you are caught in the crossfire of your screen lighting and your personal lighting it will be much harder to key in the edit.
Never light your green screen from behind or set your screen up in front of a window. Use a plain blank wall behind your screen. Set your green screen up in a dark room with the least amount of windows. Cover or black out your windows, as this will help you to control your lighting better.
Setting up your lighting will take some trial and error until you get an even light. Once you have got it sorted, make sure that you put down (placement/positioning tape marks) on the floor. It also pays to photograph your lighting set-up, number your light stands and take measurements (i.e. measure the light stand distance from the screen as in, “Light stand 2 and 3 = 4ft from the screen” etc) so that you can easily recreate it if you have to tear it down.
Hair and Clothing
Smooth hair keys better on screen. Flyaway wisps of hair are a nightmare to key out.
Avoid wearing any clothing that is close to the color of your background screen.
Avoid shiny clothing. Also note that jewellery, glasses and reflective surfaces on props can appear greenish looking once keyed, and this can be extremely challenging to fix in the edit suite.
Minimize your Movement
For a standard “talking head” video presentation with a static single camera set-up, it is important to minimize your onscreen movement. Movement can create a blur which will result in a poor key.
Also, changing your focal length midway through a shoot can also affect the outcome of your key. My suggestion is to lock-down your setup so that neither you or your background move around until you become more skilled at green screening, or want to move into high end advanced type production i.e. CGI, motion controlled cameras etc.
Screens and Equipment
I have trialed various products over the years, some with great results and some not so great. Hopefully, by sharing my experiences, it will save you time, money and creative disappointment.
I have had poor results with “hanging curtain” type screens (below image shot in my studio). These screens are not user-friendly in my experience and are time-consuming to set up. They don’t transport well and the fabric is generally cheap and see-through. They wrinkle and crease easily and have to be kept hanging, and clipped or taped into place to prevent this. Not an ideal choice if your setup has to be packed down and stored after filming.
Since 2010 I have been using “collapsible screens”. I have had excellent results with these backgrounds. In fact, I bought two; a 5’x7′ Green/Blue reversible and a Black/White reversible screen. They are lightweight but come with a sturdy spring steel frame that folds down into a disc carrying case.They are highly portable and travel well, and best of all they show no hideous creases! This particular brand has been good so far, and to date, I have not experienced any issues with them.
I have hung these background screens on my studio walls (using 3M adhesive hooks), or have filmed with them just leaning against a wall. I also use the stand-alone support stand (that comes with the kit) which clips easily onto the frame.
Big Buying Pointers
When purchasing a collapsible background, make sure that the screen is made of a professional grade material from 100% muslin cotton. It’s super important that your screen absorbs light and does not reflect it. A matte surface will have a more even color range, which is essential for getting a good key.
I have seen cheaper brands and versions of these screens using materials which are shiny or reflective. This is a big no-no! A shiny screen surface will reflect the lights and create “green spill” all over the place; rendering your footage difficult to edit.
There is much more to cover this subject like post production techniques etc which I cover in my forthcoming book. But for now, I hope this information will help make wise choices in how to use a green screen in your video presentations.
Behind the Scenes – Keying Test
Also, if you would like to get some personalized feedback on your current video presentations – let me know about it here. Thank you so much for stopping by!
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Founder of STEBIAN.com Video presentation coaching. Bianca offers a personalized virtual consulting service for rising stars and emerging leaders who want to deliver effective online video presentations.