control shadow shade

hi all,any one know a way to control the shadow shade (
from dark to lighter shade ) beside using the energy control?
In shadow buffer it seem cannot adj the value it stuck at 512.?
any work around it.

There is a simple way to control the darkness of a shadow.

1)Create you lamp and set all of its properties the way you want them

2)Turn off shadows for that lamp

3)Duplicate the lamp (Shift-D) and then Right-Click so that the two lamps are overlapping

4)Enable shadows on this new lamp, and select the “Shadow Only” button

5)Decrease the intensity of the second lamp to give a lighter shadow.