Pssst! [passing a note from the back row] If you were to consider the Angle Start and Angle End as defining the width of the falloff cones, then think of Dist Start and Dist End as defining the length (or height) of the falloff cone. A spotlight is full strength from the source until it reaches the distance outward from the light that is set in "Dist Start". From that distance onward, it then begins to diminish in intensity until it reaches zero intensity at the distance set in "Dist End".