i would say low light is without flash, my only concern with low light is that the centre of attention has some light on it,otherwise it will just be in shadow,I prefer to get some movement blur in my animated shots so its always a fine line guessing the best shutter speed to use,in this shot i knew it was going to be fairly dark with acrobats flying all over the place so i opted for 1/200th and iso 4000.got a nice balance of blur with a little sharpness.cheers martyn