If you don't have dimmers (or a light meter), you can always use the inverse square law to roughly calculate relative illumination by distance from the light to the subject.
When you double the distance, you reduce the illumination by a factor of 4. 10 feet to 20 feet equals 1/4 the light.
In order to reduce the illumination by a factor of 2, increase the distance by a factor of 1.4. (The square root of 2.) 10 feet to 14 feet equals half the light.
http://en.wikipedia.org/wiki/Inverse-square_law
It's all a complicated way of saying if you don't have dimmers, move your lights. 🙂
