Rick asks an excellent question and I would like to hear from Mike as well. What happens to the color temperature when you dim? You may be aware that some videographers are strongly opposed to mixing color temperatures on a set because it can look funny and make color correcting or color grading more difficult in post. If the lights you dim are not designed to hold their color temp through dimming, you could be putting 5400 degree light on one side of your subject and something much different on the other side as fill. I now have some "Cool Lights" (both flourescent and LED) that have dimmers built in that are supposed to keep the color temperature the same from 10% to 100%. That is a brand name and just so you know, I have no connection with the company. When ever possible, on a set, I eliminate all other light sources (including covering windows) and light with the same lights. Like Rick said, scrims cut intensity. So does the inverse square law of light. If you move a light half the distance to your subject, it gets twice as strong. A little distance goes a long way. If I buy a light, I make sure the dimming function is designed into the unit and the color temp stays constant. Another thing you want to consider is CRI or how faithfully colors are reproduced under certain lights. I didn't believe it until I bought lights with a 93+ CRI and my jaw hit the floor when I saw skin tones from those lights.