Posted 28 November 2012 - 12:42 AM
There are a number of diffusion materials available, which you can buy in sheets. Local film or theatrical lighting suppliers or rental companies can provide diffusion from manufacturers like Lee or Rosco. Diffusion 216 is a pretty standard one. If you're using the lights in your picture, because there's little heat, you could use tracing paper and place it in front of them. You could use a frame to hold it.
The larger the area the softer the light will become, you can test this effect with the diffusion material.
Spraying on anti flare can also help.