Chroma Key in video is where you have usually a green background and that is electronically keyed out to create any background you want. You tell the computer to sense any green pixels of a certain colour and brightness and they get replaced.
The system has been used extensively in feature films and broadcast TV, and now that High Definition video is widespread for everyone, it's easy to do Chroma Key yourself, and key in all sorts of virtual studios in the background, without that horrible green fringing that we used to get with Standard Definition.
I filmed a training course I have on www.Voiceovermasterclass.com
called Chromakey Challenge, where I had to work out the best way of filming in a very tight space, to get professional results. And you're very welcome to check out that video-based training course which gives you all the details.
But this is a product review, and I wanted to go through the various types of green screen curtain that I had to find to give the best results.
Over the years I have bought so many different types of green screen, and most of it is now in my shed just getting scrunched up, and probably will never be used again.
When you buy off the Internet, you have no real idea what it's going to be like till it arrives. Then you realise that the green screen material is really thin, so you need to double or triple it up so nothing shows from behind, and that is a real difficulty if you are trying to film against a window. Also you may find that the material is not dyed evenly, and it's really important for it to have the green colour evenly dyed, so that the computer can have a fighting chance of giving you a clean Chromakey. The other thing is that the material shouldn't be shiny. So many people sell green screen material and don't understand how it's going to be used by professional video makers. It needs to be matte, not shiny, it needs to be thick, not thin and its needs to be evenly dyed. What it doesn't need to be, is enormous!
As I've already proven in my own little home studio for the training course I filmed, as long as you cover the body of the presenter, it doesn't matter about anything around it, because you can get rid of it in edit. In Premiere Pro editing software, it used to be called a garbage matte. These days, you use a mask, just simply draw around the green area, and the rest simply disappears. In my training course on www.voiceovermasterclass.com, I explain how to do this in detail, and also in more than just Premiere Pro, I explain how to do it in detail in two free video editing software programmes as well. So check that out.
So what do I suggest for the best green screen? The one that I used for my little home studio, is from Westcott and it’s the Westcott 579. This is nice and thick, it has a matte surface, and it is very evenly dyed, what's more it has eyelets as well to help you hang it up. And you can also scrunch it up and fold it and those folds come out very easily when you want to use it. I first saw it on sale on the CVP website which is a UK based professional broadcast supplier, so I thought it might be pretty good, but they didn't have it in stock, so in the end I bought it on Amazon.
You may notice on Amazon they call it a 5 by 7 INCH cloth, which I don't think would be very useful! They really meant to say 5 foot by 7 foot! You'd think they'd check the copy before they advertise wouldn't you! So that's our choice for the best green screen for a single person presenting, and larger ones from the Westcott company are also available.
However, what happens when you have a presenter who wants to wear a green shirt! What if they can't change their shirt, as its company uniform, and you need to film them wearing the green shirt! This is where we go back to the 70s! Back in the 70s, the electronics was set up in a way so that blue screen was actually the best background to use for keying.
Westcott do make a blue screen as well, and its larger, 9 foot by 10 foot, and you see it here on the Amazon site where bizarrely they still call it 9 inches by 10 inches, maybe they do a version aimed at Barbie doll filming or something! But it definitely is 9 foot by 10 foot in size. Anyway this is a very good blue screen, but our final choice today has the best of both worlds, as there are many screens which have blue on one side and green on the other.
This is from Godox and it’s very cheap; the cut isn’t brilliant and the material does need folding properly to avoid creases, but if you’re on a budget it keys well on both the blue and the green sides.
Finally, what about if you're filming different people, maybe in their houses or at their workplace and you need a quick green screen to pop up behind them? There are plenty of really cheap pop-up screens that have a metal hoop inside that you'll find online, but I've had my fingers burnt by buying cheap and regretting it later, with think material and uneven green dying, so the only one I can really recommend is unfortunately the most expensive, but it will give you very good green screen results, and is very well made, and will last for years.
It's made by Lastolite. It’s 1.5 by 1.8 metres, you can get both only green or green / blue reversable and it’s about $225. You take it out the bag and it pops up into a taut perfect green screen; light it properly as I teach in my Green Screen course, and off you go!
I hope you find all this useful. To find links and more details of all our product recommendations, go to VoiceoverMasterclass.com and click top right. Good luck!