Note to self: Photos from Friday night display an unacceptable level of spherical aberration, caused by shooting my 50 1.8 wide open under harsh contrast conditions (bright tungsten lights on light skin against a dark background). The SA disappeared when I stopped down to 2.8. If I'm going to shoot at 2.8 anyway, for Saturday night I will use a more modern lens with better element design and coating. Since I'll be shooting the 17-55 wide open, and the conditions exceed the dynamic range of any camera sensor, I'll err on the side of exposing for the highlights and letting the shadows fall where they may...