pardon, light diagonals?  please expound (if you can spare the time).  looking at images, it seems to me that there's an interesting tension between reality and vision in publicity shots.  lots seem to try to make the background not exist at all, and suspend the dancer completely.  some are even obviously postworked to acheive this.  that is to say, i think there's a range of places to take this kind of picture, and a sort of "ideal" with only a hint of reality is just as interesting to me as catching a real sense of a simple stage (without needing to see the wings or theatre).  then again, i'm not familiar at all with the physical limitations, so i don't know how well i'd ever mimic them in terms of lighting.