Noooooo! Not Math!

Inverse Square Law (Law of Inverse Squares)- If you want to work as a dp, cameraman or lighting crew, you must learn this simple concept.  The amount of light coming from any light source varies according to the square of the distance of that source. Relax, it's still not math. Physics actually!  In other words: When you move a lamp twice as far away from the subject, you'll get 1/4 the intensity. Now go try it. You can even use the light meter on an SLR camera to prove it.