you can do this easily via direct dmx/knob commands.
RB-DMX 1 How to Dim the brightness
How do I Dim the brightness of the Moving Heads without having to Dim the brightness in every scene and or Mood?
you would think we would be able to control the brightness in the lighting tab and not on the main page. When using the dimmer on the performance mode it messes with my ADJ Focus Spot 4Z's.