with zenith, by selecting all the radial lights (use the selection tools in the lower-right by pressing the weird white target looking buttons), you can enter the light lab and change the color to be brighter or darker. In the basic zenith rig, the light color is a near-white, slightly yellow color. In the moon version, I simply changed the color to a dark gray/slightly bluish color. You can mess around until you get the effect you want. A few notes: zenith is meant to work with the sun disabled, and all materials with ambience settings of zero. You can adjust the shadow intensity in the skylab without messing with the ambience of the materials. I've an indoor rig in progress, should be up by tomorrow.