Chromakey Tips

Setting up a good key can be hard sometimes. Here are some basic steps that you can use to help you with keying using your Roland switcher.

- Always try and find the best quality green screen. Good Keying always starts with a solid even background. There are various scenarios where you would use a portable green screen background. Some of which involves fabric. If you are using a fabric green screen make sure that the fabric doesn't have wrinkles, stains or the obvious tears. For permanent painted background installations of course just make sure the maintenance on green screen is kept up. And always have extra paint in case you need to touch up the background before your shoot.

- Lighting is very important when keying. Before putting your subject in front of the screen first you have to make sure that the background is lit very well to ensure the green is bright and even. Overhead lights illuminating the back ground is recommended.

- To check if lighting is even on a background you can use a waveform vector scope (if available). But sometimes that tool is unavailable or too expensive so in most cases a cameras' Zebra tool is used. Most consumer cameras will have this feature built in. The Zebra tool will allow you to see if you have hot spots (overexposure points) on your background. When the background is lit properly then you will see the viewfinder on your camera display an even zebra pattern on the background.

- Make sure that your subject is far enough from the background that you don't cast a shadow onto the background or worse have green/blue reflect on your subject. Making it really difficult to key out your subject. This will vary depending on the space you have to work with. For head and torso shots a safe distance is about 5 ft-10 ft.  If you want a full body key then you will need a larger space and add more lighting.

- You want to make sure that the lighting on your subject is not as bright as it is on the green screen background. That will create hot spots on your subjects face and hair. Most of the time there is a over head light facing the subject lighting the face, hair and upper body. And a light on floor facing upward or towards your subject to light the arms, legs and lower body. Lighting the floor helps avoid a shadow casting on the green screen floor. 

- It's important that you are mindful in what you wear when you will be in front of a green screen. Here's a list of tips on Do and Don'ts in front of the green screen:
     
      1. Do not wear Green/Blue (obvious one here).
      2. Do not wear patterns (makes keying difficult)
      3. Do not wear glasses (some times the background will reflect)
      4. Do not wear shorts (particularly if you are in a virtual set)
      5. Do not wear too much Jewelry (causes reflection issues)
      6. Do not tease or have frizzy hair (makes keying very difficult)
      7. Wear make up it will help you look better in front of the camera
      8. Bring a towel to wipe off any sweat (it looks like greasy skin on camera)

So these are some basic tips to help you achieve a better key. I hope this helps you with you production. Make sure that you give yourself plenty of time for setup. A good setup and test run will give you the best results on your production.

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