Green Screen Filming – how easy is it and what’s required?
September 17th, 2013
Green screen filming: you’ve seen it being done for television, may have even seen it being used for other corporate videos. But how easy is it to achieve and what are the things to consider when approaching a production company to do it for you?
Some production companies resort to hiring out a studio with a chroma-key facility, but this can be expensive. At Ceres Productions, we have two methods of green screen filming available to us, and both are portable, which means, on the proviso your choice of location suits the filming logistics, we can just as easily come to you.
What are those logistics of green-screen filming, then?
1. A sufficiently large and uncluttered space is required.
2. Controlled lighting allowing for house lights to be turned off and no mixing of colour temperatures.
3. Power for a minimum of five lights, and preferably the camera too.
4. Controllable air conditioning – it will get hot with all those lights on, but you will want to turn it off during filming to keep sound issues to a minimum.
5. The presenter should avoid any green in their clothing. So no green tie! It is also best to avoid wearing white. Darker colours are best. Perhaps bear in mind the colour of the graphics that will replace the green screen in the edit and consider how your choice of colours might better complement them. (While on the subject of clothing, it’s worth mentioning that one should avoid fabrics with complicated patterns or tight stripes on-camera, as this can cause a fluttering effect. – for further tips for presenting to camera, feel free to view our article: ‘Top Tips for Presenting to Camera’.)
A minimum of five lights is needed for this set-up. Firstly, light the green screen, which needs to be either a painted surface or a drop that has been pulled taut to allow minimal folds and creases. Some companies prefer to rig a truss above the screen and have the lights there, but this requires a higher ceiling and more heaving equipment to lug around. We’ve had equal success by placing a light either side of the screen, on flood and softened with diffusion, at sufficient distance to provide an even spread of light. Sometimes a bit of .3 ND is required on that part of the light hitting the nearest part of the screen to help with getting that even spread.
The room has to have enough space for the presenter to be able to stand sufficiently far away from the screen to ensure there is no spill or bounce from the screen to hit them. Once the screen is satisfactorily lit, those lights should then be turned off and the presenter should be lit. Three lights should be sufficient for a classic three-point lighting set-up on the presenter: a key or front light, a fill light and back light. It is advisable to light the screen a few stops brighter than the presenter.
The camera should be roughly equidistant from the presenter as the presenter is from the screen so that the operator can zoom in and achieve a slightly narrower depth of field. This means that while the presenter remains in focus your green drop is slightly softer, helping give a more even spread of green behind your subject and ensure any blemishes in the fabric or paint is neutralised.
A marker should be placed down for the presenter to know his or her exact position. Ideally, they should be framed so that neither side of their shoulders or hands should clip the edge of frame. This will give the editor more leeway to re-position them during the edit.
Some matte powder should be applied to the presenter to remove any sheen from their face and head, which may result in a poor key. This is particularly important if the presenter is bald!
The camera operator may wish to increase the shutter speed on the camera up to no more than 1/150, as this will reduce motion blur and provide a better key. Be wary of ramping it up too high, though.
Shadow-spill on the screen, while not ideal, is not a problem so long as that shadow does not bisect the subject as seem in the recording frame at any time. Be aware that while just prior to filming this may be the case, as soon as the presenter begins to speak and move his arms it may then become an issue as his arm bisects that section of the screen.
Allow around two hours set-up time as getting the lighting just right is critical to achieving green screen filming success.