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Creating the illusion Green screen lighting by David Morphy I f good cinematography is about creating the illusion of three dimensional reality, on a two dimensional screen. Working to create reality using background plates offers a whole new variety of technical issues that need to be addressed with skill if it is going to be successful. In this article I will touch on some of the basic issues that need to be taken into account in order to pull off the illusion of “Reality”, and done well it is a creative process and can be very rewarding. First step The first step in the creative process is to evaluate the background plate or overlay image. You may or may not have shot the background plate yourself, either way you will need to make some decisions, for example: Camera: Position of the camera, set up of camera including lens and lens height, iris and white balance. Optical quality of Key and Back light: What type and time of day is it? Exterior, interior, sunny, cloudy, evening or night? What quality key light will you need to use to replicate the background lighting. Obviously a sunny day would be represented by a hard key with crisp shadows. A cloudy day would use a softer diffuse light and a nigh exterior could have some wonderful moody colours motivated by streetlights and shop windows Direction of light: Most importantly, where would the key come from - which direction are the shadows falling? Get this wrong and there is no true illusion. The human brain subliminally picks up these subtle and fine details. Colour quality: You will need to match the foreground to the background Subject position in frame: Where can you naturally place the subject? Lighting the screen Essentially there are a few rules for trouble free green screens. Here are some of the most essential: Even Flat Lighting - to within 1/3rd of a stop. Try using a spot meter. This works best for me. The most common method for this and an international standard are 4’ 4Banks from Kino Flo. These have several advantages. Firstly they are large soft sources with wide reflectors that help multiple units blend the light together seamlessly. This system will dramatically reduce the set up time , the amount of units required and offer excellent colour that keeps contamination of the subject to a minimum. Lamp Colour Choice - It is essential to avoid the contamination of green light onto the subject. There are several ways to do this, however with digital cameras and green screens the most successful combination I find is the use of the KF3200 lamp from Kino Flo. In features and commercials on large stages the use of narrow wavelength (special effects) blue and green tubes are used, however in broadcast studios it is more common to see the screen lit with KF3200 bulbs - this provides good colour for the green screen (better that naked tungsten) but further to that, any direct contamination from the lights will not affect the foreground. In some cases where space is an issue the Kino’s can be used in a vertical position and light both the screen and rim light the subject at the same time. Other colour choices for lighting the screen are appropriate depending on circumstance for example blue screen - or large screens however the above system is the most popular professional system currently in use – and has a proven track record. Avoid contamination - keep your subjects as far from the screen as possible. In my book, a minimum of 2m is required If this is not possible, careful use of backlights can help alleviate some of these issues. Avoid light with corrupt or a non- continuous colour spectrum- It can be 76 | TV-BAY MAGAZINE TV-BAY074FEB13.indd 76 11/02/2013 16:54