We have recently completed some work in a green screen studio. These are my notes on how a green screen studio project can work well. I’ll discuss what could be done better & what we would we do differently again.
Using a Green Screen in a project is a bit of a minefield, they solve a lot of problems but can create a lot of others. Even for top Hollywood films they can be a budget busting project for some of the best studios. I found it interesting that some studios have resorted to back projection, like they did in the 1950’s. There is even a newer version of back projection that depends on performing in front of a large video screen!
Fortunately the goals for these projects were more limited but still presented a number of challenges.
The best advice I have been given is to design the project from beginning to end, start by picking a location that you want to be used as your plate. It is too easy to just film your talent and substitute a number of plates in post production, just because you can do that it does not mean you should. Even if you are filming a sci-fi project, where you want a fantasy plate, you should still plan that project fully.
Planning your Project
The main thing to plan is to conceive the scene as it will be displayed in the completed project.
It is particularly important to work out what type of light you would need. Are you preparing a daylight scene or an indoor scene? You would ideally like to match the color temperature of the lights. In practice this is not so easy to achieve as the studio may have a default setup that does not match your requirements! Filming a subject using indoor lighting that will be used on a daylight shot can give unusual results. You can always discuss your requirements with the studio beforehand and most will oblige you – however that can come at a steep price. You are better off picking a studio that has a choice.
One of the problems that occurs with cheaper fluorescent lighting is that it has a frequency related to the local mains frequency. The best lights have a natural frequency in the 100’s of Hz and so will not beat with your camera frequency. If you get this wrong you may not notice until it is too late and it is an expensive day to waste.
Lighting
For a simulated outdoor shot, your subject needs to be standing correctly relative to your camera. Watch that you are not adding walls that are not green screen, although this can usually be fixed later. Watch out for your subject wearing glasses. Particularly with strong glasses, you can ruin your shot, making it look as though your subject has holes in their ears! You may not believe this distracts from your film but beware as the subject may not like the shot at all.
A studio with a large Green Screen is the best, particularly one where you subject can be lit standing away from that screen. Filming a subject too close to the screen can result in uneven keys.
Prompting
We used a portaprompt for the first time. These make a tremendous difference for most presenters. So much that we would definitely use one again. Without a prompter non professional presenters can give a very uneven performance. You may like to convince yourself you can ‘fix it in post’ but that can be expensive and difficult. There are problems though. The main problem was that the cheaper Portaprompt offerings are not big enough for larger rigged camera setups. So it is important to test your cameras with the prompter beforehand. Some people customise the rig to support a teleprompter. For smaller cameras one tripod can work standalone. For larger cameras a second tripod can be used.
There are other problems that need to be addressed. The software you use to scroll the text needs to match the rate the subject needs to speak. I would definitely recommend working on practising this. When the script has gaps in it there can be pauses that almost defeat the object of using a teleprompter. So as always practice makes perfect. One problem you may find is that some presenters are supremely confident of their ability to speak based upon their usual performance in meetings. Normally a teleprompter would be an additional cost item and so your subject may reject it as being unnecessary. Unfortunately these are usually the types that need Teleprompter. You need to develop the soft skills that allow you to have that Teleprompter available just in case!
Some Studios offer a Teleprompter service that comes with someone who controls the scrolling rate continuously. These are the best people to have but, naturally, the cost is raised significantly.
Software
This project was developed using Adobe Premiere Pro, of course you could used Adobe After Effects or DaVinci Resolve. DaVinci Resolve is very good but I believe you need the paid for version (Studio). Adobe After Effects is also very good but Premiere Pro now also has advanced Green Screen capability. It is still best to use published techniques as the Software is far from foolproof. I have looked at multiple videos on YouTube and they are usually excellent. However the best technique, in my opinion, is described in the book: The cool stuff in Premiere Pro. This book is now a bit dated and could probably do with a refresh but the Keying section is very good.
In the second edition of “The Cool Stuff in Premiere Pro”, go to Chapter 8 – Compositing in Premiere Pro. Then the section on Keying Skills (p712). Although we use the term “Green Screen Keying” almost any color would work. The Movie industry prefers Blue screen. What is important is getting a Color that is pure and not used by your clients. This can be trickier than it appears because modern colored patterned textiles use multiple colors and they are not always obvious. With the trend for brightly colored hair you can also get a conflict.
There are preferred Colors, Green is #00b140 and blue is #0047bb. These are RGB Colors, there are Pantone equivalents. The Studio may paint their walls to these Colors or have backdrop cloth expensively obtained from the US. Most Studios will have a Green backdrop but it does no harm to ask!
Will you Client work with the backdrop? Some blogs advise doing a limited test with a computer running keying software. This is very good advise but you are kind of stuck is there is a clash. They may have driven miles to get there, in their favorite outfit, and so your remedial actions are limited. Perhaps the best approach is to get them to decide what clothes they want to wear and send you a picture of them dressed in that outfit. Preferably a body shot that fills the image. With this you can do some advance testing with Software like Adobe Photoshop. Of course you can also use Premiere Pro. Try a plate which is a solid Magenta Color. This being the Color Wheel opposite to Green. Isolate the body of your client and put it on a green screen background – giving the image a look as though it was taken from a Green Screen shot. Now in Premiere, key out the Green layer and it should be replaced by the Magenta layer and the body. The thing to look out for is Magenta showing through the body and if there is then request a change of clothing.
The same process should be used on the shoot day. So start early and allow enough time to do some test shots and make sure you have the best key.
I had a conversation with someone that worked at a top effects house. He likes to annoy his wife by pointing out green screen keying failures in the top Hollywood Movies! Even the top studios can’t always get perfection. So it is important to solve as many problems as your can beforehand. You don’t have to due that, you can be sure of a good welcome from the post house.
Another tip for lighting is to make sure your client is evenly lit. It is easy to light the head and shoulders well and neglect the rest of their body. You will also not see the consequence of failing to do this until it is too late.
Have fun with your next green screen project.