I'm sure Dr. Geep knows more than I do, but I seem to remember that the angle start/end referred to the peak angle on the cones produced by the spot. The start angle refers to when the light begins to decrease, while the end angle refers to the outer edge of the cone. Thus, if you have angle start of 40 and angle end of 80, the light will be undiminished in the inner 40 (0 to 20 in every direction) degrees of the cone, and decrease linearly from 40 to 80 (20 to 40 in every direction), where it becomes 0. evr