In 1973 Focus were at their peak!
They simultaneously had two Top 10 albums ("Focus 3") and "Moving Waves) and two hitsingles ('Sylvia' and 'Hocus Pocus'). All of the musicians were voted as Top 10 musicians in each of their categories. Jan Akkerman was voted world's best guitarist. With a live reputation that proved Focus lived up to these 'Best Musicians' claims, it was the right thing to do to release a live album: "Focus at The Rainbow".