Scrims

These are pieces of screen that are either green which takes the light down a half stop or red, which takes the light down one stop.  You can have half scrims as well that only work with Fresnel lights.  I use the half scrims to balance the light so that it delivers an even field across an area.  So if I was lighting a back wall and wanted the light to be even at the source and at the other end of the wall, you can use the half scrim to do that.  Half singles work very well this way.  I also use them in condors to put the half scrims at the bottom because this will always be brighter.